I have no parsed this and indexed it yet, it's a CRAPLOAD of studies. There are a ton of gems in it. This is pretty much every soccer study in existence, except for a bunch of brain injury heading studies.
I'll index it later, I have brain fatigue from searching through 200 pages of google scholar.
pc
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Acta Physiol Scand Suppl. 1994;619:1-155.
The physiology of soccer--with special reference to intense intermittent exercise.The present thesis is based on 14 original articles published in international journals (I-XIV, see page 
and a summarizing review. The thesis deals with the physiological demands of soccer, with a particular focus on the physiological response to repeated intense exercise. In chapter I the specific issues are presented and in chapter II the physiological demands in soccer are discussed based on the results of the studies performed. Chapter III contains a short survey of the experiments performed to study specifically muscle metabolism and muscle fatigue with repeated intense muscle contractions. With reference to the topics covered in chapters II and III, fatigue during a soccer match is discussed in chapter IV, and chapter V deals with applications for physical training in soccer. Measurements have been performed during soccer matches and training, as well as in experiments simulating the activities of a soccer match. The information obtained has been compared to results from studies of the physical capacity of top-class soccer players and from laboratory experiments aimed at investigating metabolism and fatigue in intermittent exercise. Studies with whole-body and single muscle group exercises have been performed, the latter mainly with the application of a knee-extension model. In the studies on isolated muscle groups, biopsies taken from exercising muscles as well as arterial and femoral venous blood samples have allowed for detailed analysis of muscle ionic transportation and metabolism. In addition, the magnetic resonance technique has been used for the continuous determination of changes in muscle metabolites and pH during intermittent exercise. Analysis of activities during soccer matches showed that a top-class soccer player covers an average distance of approximately 11 km during a match. The distance differs highly between players and is partly related to the position in a team. Midfield players run more at low speed than defenders and forwards, whereas no difference appears to exist between groups when comparing the distance covered at high speed. The distance covered at high speed is the same in the beginning as in the end of a match. The total distance covered by a player during a soccer match is only to a limited extent a measure of the physiological demands on the player during the match. In addition to running, a player is engaged in many other energy demanding activities, i.e. tackling, jumping, accelerating and turning. A more precise evaluation of the total energy demand during a soccer match may be achieved by performing physiological measurements in connection with soccer matches (I).(ABSTRACT TRUNCATED AT 400 WORDS)
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Relationship Between Postactivation Potentiation of Knee Extensor Muscles, Sprinting and Vertical Jumping Performance in Professional Soccer PlayersLittle is known about the relationship between postactivation potentiation (PAP) in human muscles, assessed by enhancement of twitch torque after a conditioning maximal voluntary contraction (MVC), and performance in activities requiring power and speed. Moreover, no studies have assessed PAP in soccer players who train power and endurance simultaneously. The purpose of the present study was to examine the relationship between twitch PAP in knee extensor (KE) muscles, and sprinting and vertical jumping performance in soccer players. Fourteen professional male soccer players with mean (SD) age 20.0 (3.6) years, height 177.9 (6.9) cm and body mass 70.5 (5.7) kg) were tested for 15-m sprint time, vertical jump height in countermovement (CMJ) and squat (SJ) jumps. PAP in KE muscles was induced by a 10-s isometric MVC. Electrically evoked twitches of KE muscles were evoked before and after the conditioning MVC. Immediately after the conditioning MVC, twitch peak torque (PT) and maximal rates of torque development and relaxation were significantly potentiated. A significant negative correlation was found between 15-m sprint time and jump height in CMJ (r = -0.63) and SJ (r = -0.57). PAP of twitch PT correlated significantly positively with jump height in CMJ (r = 0.61) and SJ (r = 0.64), and negatively with 15-m sprint time (r = -0.59). In conclusion, twitch PAP in KE muscles was significantly correlated with performance in vertical jumping and sprinting in male professional soccer players, whereas the magnitude of PAP in soccer players was similar to that observed previously in power-trained athletes.
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J Sports Sci. 2009 Jan 15;27(2):159-68.
High-intensity running in English FA Premier League soccer matches.The aims of this study were to (1) determine the activity profiles of a large sample of English FA Premier League soccer players and (2) examine high-intensity running during elite-standard soccer matches for players in various playing positions. Twenty-eight English FA Premier League games were analysed during the 2005-2006 competitive season (n=370), using a multi-camera computerised tracking system. During a typical match, wide midfielders (3138 m, s=565) covered a greater distance in high-intensity running than central midfielders (2825 m, s= 73, P=0.04), full-backs (2605 m, s=387, P < 0.01), attackers (2341 m, s=575, P < 0.01), and central defenders (1834 m, s=256, P < 0.01). In the last 15 min of a game, high-intensity running distance was approximately 20% less than in the first 15-min period for wide midfielders (467 m, s=104 vs. 589 m, s=134, P < 0.01), central midfielders (429 m, s=106 vs. 534 m, s=99, P < 0.01), full-backs (389 m, s=95 vs. 481 m, s=114, P < 0.01), attackers (348 m, s=105 vs. 438 m, s=129, P < 0.01), and central defenders (276 m, s=93 vs. 344 m, s=80, P < 0.01). There was a similar distance deficit for high-intensity running with (148 m, s=78 vs. 193 m, s=96, P < 0.01) and without ball possession (229 m, s=85 vs. 278 m, s=97, P < 0.01) between the last 15-min and first 15-min period of the game. Mean recovery time between very high-intensity running bouts was 72 s (s=28), with a 28% longer recovery time during the last 15 min than the first 15 min of the game (83 s, s=26 vs. 65 s, s=20, P < 0.01). The decline in high-intensity running immediately after the most intense 5-min period was more evident in attackers (216 m, s=50 vs. 113 m, s=47, P < 0.01) and central defenders (182 m, s=26 vs. 96 m, s=39, P < 0.01). The results suggest that high-intensity running with and without ball possession is reduced during various phases of elite-standard soccer matches and the activity profiles and fatigue patterns vary among playing positions. The current findings provide valuable information about the high-intensity running patterns of a large sample of elite-standard soccer players, which could be useful in the development and prescription of specific training regimes.
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Muscle adaptations and performance enhancements of soccer training for untrained men
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Neuromuscular and Lower Limb Biomechanical Differences Exist Between Male and Female Elite Adolescent Soccer Players During an Unanticipated Side-cut ManeuverBackground: Female athletes are 2 to 8 times more likely than male athletes to injure the anterior cruciate ligament during a non-contact athletic maneuver. Identifying anterior cruciate ligament injury risk factors in female athletes may help with the development of preventive training programs aimed at reducing injury rates.
Hypothesis: Differences between genders in lower limb kinematics, kinetics, and neuromuscular patterns will be identified in an adolescent soccer population during an unanticipated side-cut maneuver.
Study Design: Controlled laboratory study.
Methods: Forty-two elite adolescent soccer players (21 male and 21 female) performed an unanticipated side-cut maneuver, with the 3-dimensional kinematic, kinetic, and electromyographic lower limb data being analyzed using principal component analysis.
Results: The female athletes had higher gastrocnemius activity, normalized to maximal voluntary isometric contractions, and a mediolateral gastrocnemius activation imbalance that was not present in the male athletes during early stance to midstance of the side-cut. Female athletes demonstrated greater rectus femoris muscle activity throughout stance, and the only hamstring difference identified was a mediolateral activation imbalance in male athletes only. Female athletes performed the side-cut with less hip flexion and more hip external rotation and also generated a smaller hip flexion moment compared with the male athletes.
Conclusion: This is the first study to identify gender-related differences in gastrocnemius muscle activity during an unanticipated cutting maneuver.
Clinical Relevance: The increased and imbalanced gastrocnemius muscle activity, combined with increased rectus femoris muscle activity and reduced hip flexion angles and moments in female subjects, may all have important contributing roles in the higher noncontact ACL injury rates observed in female athletes.
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Effect of plyometric training on sand versus grass on muscle soreness and jumping and sprinting ability in soccer players
Conclusions: Plyometric training on sand improved both jumping and sprinting ability and induced less muscle soreness. A grass surface seems to be superior in enhancing CMJ performance while the sand surface showed a greater improvement in SJ. Therefore, plyometric training on different surfaces may be associated with different training-induced effects on some neuromuscular factors related to the efficiency of the stretch-shortening cycle.
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2009: Dehydration: Cause of Fatigue or Sign of Pacing in Elite Soccer?x.
2 : JOURNAL OF PSYCHOLOGICAL SCIENCE SUMMER 2008; 7(26):190-205.
COMPARISON OF NARCISSISM BETWEEN THE SOCCER PLAYERS IN DIFFERENT LEVELS
Probably just due to the special attention that people pay to soccer players, the narcissism in them must be more than normal people. The aim of current research is the comparison of narcissism between the soccer players who play in different levels and the lay people.
This research is descriptive. Target population included of all players who play in different levels in Isfahan, for this purpose 115 subjects of three groups of football players from different clubs, universities and some university students containing 36 soccer club players, 34 university soccer players and 45 university students chosen randomly. Data are gathered using the narcissism scale of Ruskin and Terry and the Personality Questionnaire of Eyseneck (EPQ) and was analyzed by the use of analysis of variance (ANOVA) and the follow-up of Newman-Kweles.
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Summary
Chronobiology International
2007, Vol. 24, No. 3, Pages 507-519 , DOI 10.1080/07420520701420709
Diurnal Variation in Temperature, Mental and Physical Performance, and Tasks Specifically Related to Football (Soccer)
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J Orthop Sports Phys Ther. 2007 May;37(5):260-8.
Lower extremity muscle activation and alignment during the soccer instep and side-foot kicks.
STUDY DESIGN: Controlled laboratory study. OBJECTIVES: To quantify phase duration and lower extremity muscle activation and alignment during the most common types of soccer kick-the instep kick and side-foot kick. A second purpose was to test the hypotheses that different patterns of lower extremity muscle activation occur between the 2 types of kicks and between the kicking limb compared to the support limb. BACKGROUND: Soccer players are at risk for lower extremity injury, especially at the knee. Kicking the soccer ball is an essential, common, and distinctive part of a soccer player's activity that plays a role in soccer player injury. Regaining the ability to kick is also essential for soccer athletes to return to play after injury. METHODS: Thirteen male soccer players underwent video motion analysis and electromyography (EMG) of 7 muscles in both the kicking and supporting lower extremity (iliacus, gluteus maximus, gluteus medius, vastus lateralis, vastus medialis, hamstrings, gastrocnemius) and 2 additional muscles in the kicking limb only (hip adductors, tibialis anterior). Five instep and 5 side-foot kicks were recorded for each player. Analysis-of-variance models were used to compare EMG activity between type of kicks and between the kicking and nonkicking lower extremity. RESULTS: Five phases of kicking were identified: (1) preparation, (2) backswing, (3) limb cocking, (4) acceleration, and (5) follow-through. Comparing the kicking limb between the 2 types of kick, significant interaction effects were identified for the hamstrings (P = .02) and the tibialis anterior (P<.01). Greater activation of the kicking limb iliacus (P<.01), gastrocnemius (P<.01), vastus medialis (P = .016), and hip adductors (P<.01) occurred during the instep kick. Significant differences were seen between the kicking limb and the support limb for all muscles during both types of kick. CONCLUSIONS: Certain lower extremity muscle groups face different demands during the soccer instep kick compared to the soccer side-foot kick. Similarly, the support limb muscles face different demands than the kicking limb during both kicks. Better definition of lower extremity function during kicking provides a basis for improved insight into soccer player performance, injury prevention, and rehabilitation.
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Br J Sports Med 2007;41:439-441 doi:10.1136/bjsm.2006.034405
Use of permitted drugs in Italian professional soccer players
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Rapid Muscle Force Capacity Changes after Soccer Match Play x.
Physiological Aspects of Soccer Refereeing Performance and TrainingThe role of the referee is far from minimal in the economy of soccer, as very often, particularly in professional soccer, a wrong judgment may have profound implications on the outcome of the game. In this regard, a better knowledge of soccer refereeing can obviously benefit the game. Recent studies have shown that during a competitive match, an elite soccer referee may cover 9-13km attaining approximately 85-90% and approximately 70-80% of maximal heart rate and maximal oxygen uptake (V-dotO2max), respectively. Of the total distance covered about 4-18% is covered at high intensity. Blood lactate concentration has been reported to be in the range of 4-5 mmol/L; however, during competitive matches, blood lactate concentrations as high as 14 mmol/L have been observed. This figure is similar to that extensively reported for soccer players, specifically paralleling that observed in midfield players. However, compared with players, referees are 15-20 years older, often have a non-professional status and cannot be substituted during the game. Furthermore, this important physical stress superimposes onto a high perceptual-cognitive workload throughout the entire game. In relation to fitness status, referees possess V-dotO2max values somewhat lower than the players they officiate, with mean values in the range of 44-50 mL/kg/min. However, the methods used by the Federation Internationale de Football Association and the Union of European Football Associations to test referee fitness need to be changed as the current fitness tests do not relate to match performance. More task-specific tests such as the Yo-Yo Intermittent Recovery Test (YYIRT) have been devised and validated for use with referees. Given that aerobic performance is positively correlated with match performance, it is important that referees are trained to improve their ability to cover large distances during a match and also to repeat high-intensity efforts. A number of studies have shown large improvements in YYIRT performance following both short-term (12 weeks) and long-term (16 months) high-intensity interval training. Future research needs to focus on a number of important areas including the decision-making ability of referees when officiating under different conditions, such as high thermal strain, and the impact of age on both physical and mental performance.
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The Status Quo and Problems of Juvenile Soccer in ChinaWith the methods of documentary review,investigations,and statistical analysis,the status quo of Chinese juvenile soccer is researched including training-administering mechanism,team's status,training and competition mechanism,investment,construction of the training theory and rule of law.The results show that the main problems of Chinese juvenile soccer at present are as follows: an absence of strategy concern to juvenile soccer,faultiness of administering and operating mechanism,ambiguity of the training guidelines,ignoring the rules of juvenile growing and cultivation,being eager for quick success and instant benefit,the low level of the coaches as a whole,and the lag of the coaches' cultivation.Some corresponding suggestions are put forward.
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Int J Sports Med. 2008 May;29(5):366-71. Epub 2007 Jul 5.
Effects of repeated bouts of soccer-specific intermittent exercise on salivary IgA.Failure to recover fully between sessions has been suggested to cause immunodepression. Therefore, the cumulative effects of soccer-specific intermittent exercise undertaken on different days 48 h apart on salivary IgA, cortisol and total protein concentration were investigated. Nine male subjects completed two trials of soccer-specific intermittent exercise 48 h apart on a motorised treadmill. Timed unstimulated saliva samples were collected immediately before and after exercise, and 24 and 48 h post-exercise. Salivary IgA concentration (EX (1): 215 +/- 160 to 335 +/- 246 and EX (2): 144 +/- 93 to 271 +/- 185 mg . l (-1), p = 0.007), osmolality (p = 0.001) and total protein (p = 0.001) increased immediately following exercise in both trials and decreased 24 h afterwards, whereas saliva flow rate decreased significantly (p = 0.015) before returning to pre-exercise values 24 h postexercise. The IgA secretion rate, IgA to osmolality ratio, IgA to total protein, solute secretion rate, total protein secretion rate, and cortisol did not differ between the time-points. The results suggest that performing two bouts of moderate intensity soccer-specific intermittent exercise 48 h apart does not suppress resting salivary IgA concentration significantly although a small progressive reduction in salivary IgA was observed. These findings may not extend to successive competitive soccer games when vulnerable players might experience clinically relevant reductions in s-IgA.
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The relationship between peak height velocity and physical performance in youth soccer playersx.
Cross-sectional investigation of indices of isokinetic leg strength in youth soccer players and untrained individualsResults suggest that the muscle-loading patterns experienced in youth soccer may alter the reciprocal balance of strength about the knee under high-velocity conditions. The findings also indicate that these balances may be improved by incorporating resistance training into the habitual exercise routines of youth soccer players.
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Training and testing physical capacities for elite soccer playersElite soccer players spend a substantial amount of time trying to improve physical capacities, including aerobic endurance
and strength and the strength derivatives of speed and power.
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Effects of Sprint Duration and Exercise: Rest Ratio on Repeated Sprint Performance and Physiological Responses in Professional Soccer PlayersThe purpose of this study was to examine the physiological effects of different sprint repetition protocols on professional footballers. Of particular interest were the abilities of repeated sprint protocols to induce fatigue to an extent observed during competitive soccer. Six professional soccer players were assessed for fatigue rate and physiological responses of heart rate (HR), blood lactate (BLa), and rating of perceived exertion (RPE) during the performance of 4 repeated sprint drills, each totaling a sprint distance of 600 m. The 4 drills used 15-or 40-m sprints with 1:4 or 1:6 exercise: rest ratios. The 15-m sprint drill with 1:4 exercise:rest ratio induced the greatest fatigue (final sprint time 15% greater than initial sprint time) and greatest physiological responses. The 40-m sprint drill using a 1:4 exercise:rest ratio produced similar BLa and HR responses to the 15-m drill (13-14 mmol[middle dot]L-1 and 89% HRmax, respectively) but significantly lower RPE (mean +/- SD: 17.1 +/- 0.4 vs. 18.8 +/- 0.4, p < 0.05) and fatigue rates (11.1 vs. 15.0%, p < 0.01). Both sprint distance and exercise:rest ratio independently influenced fatigue rate, with the 15-m sprint distance and the 1:4 exercise:rest ratio inducing significantly (p < 0.01) greater fatigue than the 40-m sprint distance and the 1:6 exercise:rest ratio. The magnitude of fatigue during the 40- X 15-m sprint drill using a 1:6 exercise:rest ratio was 7.5%, which is close to the fatigue rate previously reported during actual soccer play. The present study is the first to examine both variations in sprint distances and rest ratios simultaneously, and the findings may aid the design of repeated sprint training for soccer.
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J Strength Cond Res. 2010 Jan;24(1):266-71.
Relationships of peak leg power, 1 maximal repetition half back squat, and leg muscle volume to 5-m sprint performance of junior soccer players.Performance over very short distances (1-5 m) is important in soccer. We investigated this in 23 male regional-level soccer players aged 17.2 +/- 0.7 years, filming body markers to determine the average velocity and acceleration over the first step (V(S) and A(S)) and the first 5 m (V(5), A(5)). Data were related to scores on a force-velocity test, squat jump (SJ), countermovement jump (CMJ), and 1 maximal repetition (1 RM) half back squat. Leg and thigh muscle volumes were also assessed anthropometrically. V(5) was positively correlated with leg and thigh muscle volumes (r = 0.61, p < 0.05; r = 0.43, p < 0.05, respectively), SJ power (absolute and relative to body mass, r = 0.45, p < 0.05; r = 0.43, p < 0.05, respectively), absolute force-velocity leg power (r = 0.49, p < 0.05), and 1 RM half back squat (r = 0.66, p < 0.001). The use of dimensional exponents did not change coefficients materially. V(S) was also correlated with leg muscle volume and 1 RM back half squat (r = 0.56, p < 0.01; r = 0.58, p < 0.01, respectively) and more weakly with force-velocity leg power and SJ force (r = 0.49, p < 0.05; r = 0.46, p < 0.5, respectively). However, the CMJ was unrelated to velocity or acceleration. Sprinting ability is correlated with measures of power and force such as the force-velocity test, SJ, and 1 RM half back squat; such measures thus offer useful guidance to soccer coaches who wish to improve the short-distance velocity of their players.
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Journal of Strength and Conditioning Research:
October 2009 - Volume 23 - Issue 7 - pp 1968-1973
Salivary Immunoglobulin A Response to a Match in Top-Level Brazilian Soccer Players
It has been suggested that several parameters of mucosal immunity, including salivary immunoglobulin A (s-IgA), are affected by heavy exercise either in field sports or in the laboratory environment. Few observations have been made during a true sporting environment, particularly in professional soccer. We tested the hypothesis that salivary IgA levels will be decreased after a 70-minute regulation in a top-level professional soccer friendly match. Saliva samples from 24 male professional soccer players collected before and after the match were analyzed. Salivary immunoglobulin A concentration was measured by enzyme-linked immunosorbent assay and expressed as the absolute concentration (s-IgAabs), s-IgA relative to total protein concentration (IgA-Pro), and the secretion rate of IgA (s-IgArate). Rate of perceived exertion (RPE) was used to monitor the exercise intensity.
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Changes in heart rate and blood pressure in sub-18 soccer players tested with Running-Based Anaerobic Sprint TestThe Running-Based Anaerobic Sprint Test (RAST) is an important tool for prescribing and monitoring training. The aim of this study was to evaluate cardiovascular changes by the variables heart rate and blood pressure in soccer players tested with RAST. A trial with 20 soccer players who trained daily and participated in sub-18 soccer championships. The heart rate (HR) was collected at rest (before warming) and right after the end of the test, as well as the systolic (SBP) and diastolic (DBP) blood pressure. For statistics it was used the paired t-test with p<0.05. The collected data show that the values at resting time point can be considered normal for healthy young people and after the test it was observed that the HR and SBP increased significantly as compared with resting time, and the DPB presented no statistically changes. Conclusion: The results showed that the cardiovascular changes occurring in the RAST test, which is an effort with anaerobic features, are similar to changes in high-intensity aerobic efforts.
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Eccentric Hip Adduction and Abduction Strength in Elite Soccer Players and Matched Controls A Cross-Sectional StudyBackground: Eccentric hip adduction and abduction strength plays an important role in the treatment and prevention of groin injuries in soccer players. Lower extremity strength deficits of less than 10% on the injured side, compared to the uninjured side has been suggested as the clinical milestone before returning to sport following injury.
Objective: To examine whether a side-to-side eccentric hip adduction or abduction strength symmetry can be assumed in non-injured soccer players and matched controls.
Material and method: Nine elite soccer players 19.4 (1.5) years and nine recreational athletes 19.5 (2.0) years matched for gender, height and weight were included. Eccentric hip adduction and abduction strength of the dominant and non-dominant leg was tested for all the participants using an eccentric break test with a hand-held dynamometer.
Results: The dominant leg was 14% stronger than the non-dominant leg for hip adduction in the soccer players (p<0.05). No other side-to-side strength differences existed in soccer players or controls. In soccer players, hip abduction strength was 17-30% greater than controls for the dominant (p<0.05) and non-dominant leg (p<0.001).
Conclusion: Eccentric hip adduction strength was greater in the dominant leg than in the non-dominant leg in soccer players, but not in matched controls. Eccentric hip abduction strength was greater in soccer players than matched controls, but soccer does not seem to induce a similar eccentric strength adaptation in the hip adductors.
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Accessory soleus in the athletes: literature review and case report of a massive muscle in a soccer playerx.
Comparison of standing balance between female collegiate dancers and soccer players
Gait & Posture, Volume 26, Issue 4, Pages 501-507
The hypothesis of this study was that soccer players and dancers have different balance abilities and that these differences could be objectively measured using center of pressure measurements.
Background
Center of pressure (COP) measurements are reproducible and have been validated in the literature for assessing standing balance. The literature does not provide sensitive enough techniques for discriminating between two groups of athletes with excellent standing balance.
Methods and measures
A Matscan pressure mat (Tekscan, Boston, MA) was used to compare COP change variability between 32 female collegiate soccer players and 32 dancers. COP was used to calculate sway index, center acquisition time, sway path length and sway velocity as measures of standing balance.
Results
The dancers had significantly better balance scores (p<0.05) in 5 of 20 balance tests. Results for the remaining 15 balance tests were not significantly different.
Conclusion
These data show that standing balance characteristics of dancers and soccer players can be objectively measured using COP data. Dancers have certain standing balance abilities that are better than those of soccer players. The COP measurements in this study can be used as a tool in future studies investigating standing balance in different groups of athletes.
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Carbohydrate ingestion improves performance of a new reliable test of soccer performance.The aim of the study was to investigate the reliability of a new test of soccer performance and evaluate the effect of carbohydrate (CHO) on soccer performance. Eleven university footballers were recruited and underwent 3 trials in a randomized order. Two of the trials involved ingesting a placebo beverage, and the other, a 7.5% maltodextrin solution. The protocol comprised a series of ten 6-min exercise blocks on an outdoor Astroturf pitch, separated by the performance of 2 of the 4 soccer-specific tests, making the protocol 90 min in duration. The intensity of the exercise was designed to be similar to the typical activity pattern during soccer match play. Participants performed skill tests of dribbling, agility, heading, and shooting throughout the protocol. The coefficients of variation for dribbling, agility, heading, and shooting were 2.2%, 1.2%, 7.0%, and 2.8%, respectively. The mean combined placebo scores were 42.4 +/- 2.7 s, 43.1 +/- 3.7 s, 210 +/- 34 cm, and 212 +/- 17 points for agility, dribbling, heading, and kicking, respectively. CHO ingestion led to a combined agility time of 41.5 +/- 0.8 s, for dribbling 41.7 +/- 3.5 s, 213 +/- 11 cm for heading, and 220 +/- 5 points for kicking accuracy. There was a significant improvement in performance for dribbling, agility, and shooting (p < .05) when CHO was ingested compared with placebo. In conclusion, the protocol is a reliable test of soccer performance, and ingesting CHO leads to an improvement in soccer performance.
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J Sports Sci. 2009 Jan 15;27(2):129-38.
Differences in thigh muscularity and dynamic torque between junior and senior soccer players.
The aim of the present study was to examine differences in thigh muscularity and dynamic torque between elite junior (15.7 +/- 0.2 years) and senior (22.6 +/- 2.4 years) soccer players. Cross-sectional areas of the total muscle compartment, quadriceps femoris, and hamstrings + adductors were determined using magnetic resonance imaging. Knee extension and flexion torque were also measured at 1.05 and 3.14 rad . s(-1). Neither junior nor senior players showed significant differences in cross-sectional area or torque between the dominant and non-dominant leg. The quadriceps femoris and hamstrings + adductors were significantly greater in the senior than junior players at all thigh-slice sites. The percentage of quadriceps femoris to total muscle compartment was significantly higher in the junior than the senior players, and the corresponding value of hamstrings + adductors was significant in the reverse direction. The senior players showed greater torque than the juniors regardless of motion and velocity, even in terms of torque relative to the product of the cross-sectional area and height. The present results indicate that (1) senior players are characterized by the predominant development of hamstrings and adductors and a higher dynamic torque relative to muscle size, and (2) elite soccer players did not show asymmetry in terms of the muscularity or dynamic torque of the thigh muscles irrespective of age.
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Steroid profiles of professional soccer players: an international comparative studyThe steroid profile of 57 Africans, 32 Asians, 50 Caucasians and 32 Hispanics was determined by gas chromatography-mass spectrometry. Results: Significant differences have been observed between all ethnic groups. After estimation of the prevalence of the UGT2B17 deletion/deletion genotype (African:22%; Asian:81%; Caucasian:10%; Hispanic:7%), ethnic-specific thresholds were developed for a specificity of 99% for the T/E (African:5.6; Asian:3.8; Caucasian:5.7; Hispanic:5.. Finally, another polymorphism could be hypothesized in Asians based on specific concentrations ratio of 5a-/5b-androstane-3a,17b-diol in urine. Conclusion: These results demonstrate that a unique and nonspecific threshold to evidence testosterone misuse is not fit for purpose. An athlete's endocrinological passport consisting of a longitudinal follow-up together with the ethnicity and/or the genotype would strongly enhance the detection of testosterone abuse. Finally, additional genotyping studies should be undertaken to determine if the remaining unexplained disparities have an environmental or a genetic origin.
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Effects of Fatigue Due to Contraction of Evertor Muscles on the Ankle Joint Position Sense in Male Soccer Players
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Detection of testosterone administration based on the carbon isotope ratio profiling of endogenous steroids: International reference populations of professional soccer playersBackground and objectives: The determination of the carbon isotope ratio in androgen metabolites has been previously shown to be a reliable, direct method to detect testosterone misuse in the context of antidoping testing. Here, we examine the variability in the 13C/12C ratios in urinary steroids in a widely heterogeneous cohort of professional soccer players residing in different countries (Argentina, Italy, Japan, South-Africa, Switzerland and Uganda).
Method: Carbon isotope ratios of selected androgens in urine specimens were determined using gas chromatography/combustion/isotope ratio mass spectrometry (GC-C-IRMS).
Results: Urinary steroids in Italian and Swiss populations were found to be enriched in 13C relative to other groups, reflecting higher consumption of C3 plants in these two countries. Importantly, detection criteria based on the difference in the carbon isotope ratio of androsterone and pregnanediol for each population were found to be well below the established threshold value for positive cases.
Conclusion: The results obtained with the tested diet groups highlight the importance of adapting the criteria if one wishes to increase the sensitivity of exogenous testosterone detection. In addition, confirmatory tests might be rendered more efficient by combining isotope ratio mass spectrometry with refined interpretation criteria for positivity and subject-based profiling of steroids.
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Int J Sports Med. 2009 Aug;30(:607-13. Epub 2009 Mar 19.
How well do skinfold equations predict percent body fat in elite soccer players?The use of generic equations for estimating percent body fat from skinfold thicknesses can be criticised when applied to specific sports. The present aims were to compare existing methods of using skinfold data and to derive an equation for predicting body fat values in professional soccer players. Forty-five professional soccer players (24.2 +/- 5.0 years; 82.0 +/- 8.5 kg; 1.82 +/- 0.07 m) participated. Skinfold thicknesses were assessed at eight sites for the application of existing prediction equations. Skinfold data were also utilised to determine a novel soccer-specific equation. All players had a reference estimate of percent fat by dual-energy x-ray absorptiometry (DXA). The existing skinfold equations differed from the DXA-referenced values by varying degrees, the equation of Withers et al. (1987) demonstrating the lowest bias and highest relationship and agreement with DXA. Regression analysis resulted in an equation incorporating anterior thigh, abdominal, triceps and medial calf sites, accounting for 78.4% variance in DXA criterion values.
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2010: Influence of Individualized Training on Psychomotor Performance of Young Soccer PlayersThe aim of this study was to analyze the influence of individualized training (IT) on psychomotor performance of young soccer players. Psychomotor performance was measured by means of differential response time and number of correct responses to audio and visual stimuli. Kinematic analysis allowing assessment of both the distances and the average speeds of young players during consecutive matches was also performed. For the data analysis, one-way analysis of variance, Friedman test, and t-test for dependent samples were used. The obtained results clearly indicate that IT during the preparation period increases specific psychomotor performance among young soccer players.
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Br J Sports Med 2009;43:186-190
Effects of exercise intensity on lymphocyte H2O2 production and antioxidant defences in soccer players
Objective: Physical exercise is capable of enhancing or suppressing the immune response depending on the intensity and duration of exercise. This study investigated how exercise intensity influences the lymphocyte antioxidant response and the induction of cellular oxidative damage.
Design: Eighteen voluntary male pre-professional soccer players participated in this study. Sportsmen played a 60 min training match, and were divided into three groups depending on the intensity degree during the match: low, medium and high intensities.
Measurements: Malondialdehyde (MDA), vitamins C and E and haem oxygenase-1 (HO-1) gene expression were measured in lymphocytes. Reactive oxygen species (ROS) production was determined in lymphocytes and neutrophils.
Results: Lymphocyte MDA levels and H2O2 production were significantly increased in the group which performed the most intense exercise. Neutrophil counts and ROS production increased progressively with the exercise intensity. Vitamin C significantly decreased after exercise in the highest-intensity group in comparison with initial values, whereas vitamin E levels significantly increased in the medium and high-intensity groups. HO-1 gene expression significantly increased in the medium and high-intensity groups.
Conclusions: Exercise intensity affects the lymphocyte and neutrophil oxidant/antioxidant balance, but only exercise of high intensity induces lymphocyte oxidative damage.
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Z Orthop Unfall. 2010 Jan 22. [Epub ahead of print]
Comparison of Trunk Muscle Strength of Soccer Players with and without Low Back Pain.AIM OF THE STUDY: Low back pain in soccer players is one of the frequently appearing disorders caused by overuse. Myogenic dysbalances are under discussion as possible reason for this problem. In the present study the muscular strength profile of the trunk musculature of soccer players with and without low back pain was evaluated. The results of the asymptomatic players were compared to those of players with low back pain; furthermore, the collected data were compared to those of an asymptomatic reference group. The question posed was whether soccer players show a specific strength profile caused by the special, sports-specific requirements and whether this strength profile differs between players with and without low back pain. METHOD: In the present study the isometric maximal strength of 18 soccer players with and 18 soccer players without low back pain was measured in all 3 planes. The reference group was provided by the Proxomed(R) company, which had previously analysed 1045 healthy untrained individuals of various age groups. RESULTS: The soccer players showed a sport-specific profile for the musculature, which was determined by a significant reduction of the flexion and rotation strength (flex: slashed circle 5.21 N/kg vs. slashed circle 6.49 N/kg; slashed circle 5.78 N/kg vs. slashed circle 6.66 N/kg respectively; rotation: left 7.09 N/kg, right 8.69 N/kg vs. left/right 10.1 N/kg; left 7.22 N/kg, right 8.24 N/kg vs. left/right 10.0 N/kg, respectively) as well as by an increased lateral flexion strength to the right-hand side in comparison to the reference group (lat. flex. right: 9.87 N/kg, respectively, 10.67 N/kg vs. 8.3 N/kg). A statistically significant correlation between the muscular activitiy in the trunk stability of soccer players with and without low back pain could not be shown. CONCLUSION: Obviously sports-specific training with additional specific training of the trunk muscles is not sufficient for the development of a balanced strength of trunk musculature. In the present study an influence of the performance of the trunk musculature on the incidence of low back pain could not be shown.
x.
Int J Sports Med. 2010 Mar;31(3):192-197. Epub 2010 Feb 15.
The Use of the Functional H:Q Ratio to Assess Fatigue in Soccer.The aim of this study was to investigate the effects of fatigue induced by a field test representative of soccer specific movements on different hamstrings:quadriceps ratios in the dominant and non-dominant legs at two different velocities. Eight male football players (age: 21.3+/-2.3 years; height: 178+/-8 cm; body mass: 78+/-9 kg; playing level: British University Southern conference-3B) performed a pre-test to assess the concentric and eccentric strength of the hamstrings and the quadriceps at 60 degrees .s (-1) and 180 degrees .s (-1), The Loughborough Intermittent Shuttle Test (LIST) to simulate soccer, and a post-test similar to the pre-test. The main findings demonstrated significant decreases in the H (con):Q (con) ratio (calculated as the maximal concentric hamstrings strength divided by the maximal concentric quadriceps strength) in the dominant leg at 180 degrees .s (-1) and in the functional ratio H (ecc):Q (con) (calculated as the maximal eccentric hamstrings strength divided by the maximal concentric quadriceps strength) in the dominant leg at 60 degrees .s (-1) and 180 degrees .s (-1). In addition, significant correlations were observed between physiological parameters measured during the soccer-specific exercise and H (ecc):Q (con) only. These results suggested that the functional H (ecc):Q (con) ratio is more representative of fatigue induced by soccer than the conventional H (con):Q (con) ratio. Eccentric strength training at high velocities may be necessary to reduce injury risk in soccer players.
x.
Br J Sports Med 2005;39:24-28
Endurance training and testing with the ball in young elite soccer players
Results: The distance covered in the Hoff test correlated significantly with maximum oxygen uptake, and improved by 9.6% during the 8 week training period, while maximum oxygen uptake and running economy improved by 12 and 10%, respectively. Backward multiple regression showed maximum oxygen uptake to be the main explanatory variable for the distance covered in the Hoff test.
Conclusion: The present study demonstrated a significant correlation between laboratory testing of VO2max and performance in the Hoff test. Furthermore, training induced improvements in VO2max were reflected in improved performance in the Hoff test. We suggest that it should be a goal for active U-15 soccer players to cover more than 2100 metres in the Hoff test, as this requires a VO2max of above 200 ml/kg0.75/min, which should serve as a minimum in modern soccer.
x.
Journal of Strength and Conditioning Research:
September 2008 - Volume 22 - Issue 5 - pp 1394-1401
Hydration, Thermoregulation, and Performance Effects of Two Sport Drinks during Soccer Training Sessions
x.
Season-to-season variations of physiological fitness within a squad of professional male soccer players Interestingly, AT significantly varied where VO2 max
was stable and these variations also coincided with on- and off-
seasons suggesting that AT is a better indication of acute train-
ing state than VO2 max.
x.
The Influence of Soccer-Specific Fatigue on Peak Isokinetic Torque Production of the Knee Flexors and Extensors
x.
Repeated-sprint ability in professional and amateur soccer playersThese results show that RSA performance, the physiological response to the HIT, and differentiate between professional- and amateur-standard soccer players. Our results also show that RSA performance is related to VO2 max, , and selected physiological responses to a standardized, high-intensity, intermittent exercise.
x.
Running economy in early and late maturing youth soccer players does not differ[qoute]
Purpose: The aim of this study was to investigate the influence of maturity on running economy in a population of young soccer players.
Methods: 13 boys (mean age 14.3 years) active in soccer were divided into two groups: 6 early and 7 late maturers. Anthropometrical characteristics, respiratory exchange ratio, heart rate and maximal oxygen uptake were measured. Running economy was assessed at three submaximal running speeds (8, 9.5 and 11 km/h). Allometric coefficients were calculated and used to diminish the effect of body mass. In addition, running style was analysed biomechanically (stride length and meaningful kinematic values).
Results: There was no significant difference in the running economy of early and late maturing soccer players, nor any significant differences in mass adjusted physiological values. Therefore physiological differences cannot explain why late maturers succeed in keeping up with early maturers. Late maturing boys take longer relative strides, and have more anteversion of the thigh at heel contact, a smaller knee-angle during swing-phase and a lower mass moment of inertia.
Conclusion: Running style seems to be an important determinant in running economy of children.[/quote]
x.
2010: Intensity and Duration of Intermittent Exercise and Recovery During a Soccer MatchSoccer is a sport consisting of high-intensity intermittent exercise, with players making forays across their anaerobic threshold for tactical advantage followed by periods of recovery. The intensity and duration of these work and recovery bouts were defined during a men's soccer match using StepWatch Activity Monitors recording step rate for each 3-second period. The data were coded by custom software to separate work bouts (step rate >= 4) from recovery bouts (step rate < 4), and a square wave of the pattern of bouts was plotted for 5 players: center forward, central midfielder, wing midfielder, central defender, and wing defender. Four values were calculated for each work and recovery bout identified: duration, and mean, maximum, and minimum step rate (intensity). This novel technique provided detailed graphical information on the duration and exercise intensity of each position throughout the match. The center midfielder was able to sustain work and recovery bout characteristics throughout the match and appeared to recover at higher intensity levels than other players. The forward showed the consequence of accumulated fatigue late in the match and was unable to sustain the duration of high-intensity work bouts observed earlier in the match. The central defender attenuated the intensity of his work and recovery bouts late in the match staying closer to a more moderate work rate with fewer high- or low-intensity bouts. Having objective data qualifying players' work and recovery bout characteristics might prove valuable for tactical decision making, substitution timing, and for planning future training sessions.
x.
2008: Evaluation of the Reliability of Soccer-Specific Field TestsWith the exception of the throwing-in and standing kick, the evaluated tests revealed high intraclass correlation coefficients (i.e., >0.80), small within-individual variations (coefficient of variation, <4%), and sample sizes for detecting a 2% change in the tested performance that are either close to or below the standard size of a professional soccer squad. In addition to simplicity and face validity, most of the evaluated tests revealed high reliability. Therefore, the evaluated tests are recommended for sport-specific profiling and early selection of young athletes as well as for routine testing procedures that could detect effects of various intervention procedures. Regarding the throwing-in and standing-kick tests, direct measurement of the ball velocity (e.g., with a standard radar gun) is recommended.
x.
Actual and perceived running performance in soccer shoes: A series of eight studies Soccer shoes in general but especially their outsoles are important for running and consequently playing performance. This article aims to quantify running performance and perception of running performance due to type of footwear and surface condition by use of Functional Traction Courses (FTC). Soccer players were required to run through slalom and acceleration courses as fast as possible providing running time and perception of running time variables due to wearing different soccer footwear. A series of eight single studies featuring different types of soccer footwear and different surfaces was conducted. The influence of footwear (subject Means and SD) was analyzed by Repeated Measures ANOVA, followed by post-hoc t-tests when appropriate. Slalom running times were considerably affected by altered shoe/surface interface conditions, whereas acceleration running times were affected only to lesser extent. Running time perception of athletes generally reflected actual running performance. Running performance differed about 3% when altering stud type or stud geometry. Thus, players benefit by the appropriate choice of footwear for a given surface. Complete elimination of studs resulted in a running time difference of 26% compared to normal condition. Surface conditions may be responsible for up to 20% of performance differences. It is recommended to include FTC testing in the evaluation of soccer footwear to get an idea of potential running performance benefits for players.
x.
A 90 minute soccer match decreases triglyceride and low density lipoprotein but not high-density lipoprotein and cholesterol levelsCONCLUSIONS: Although the soccer competitive match has no favourable acute effect on lipid profiles, the lower rate of
LDL, cholesterol and triglyceride as well as the higher level of HDL in players suggest a beneficial effect of regular
soccer training on arthrosclerosis and perhaps on CHD risk as well
x.
The Relationship Between Preseason Range of Motion and Muscle Strain Injury in Elite Soccer PlayersThe purpose of the study was to determine the influence of preseason lower-extremity range of motion (ROM) on the risk of muscle strain injury during a competitive season for elite soccer players. Thirty-six elite male soccer players (age, 25.6 = 4.7 years) had maximum static ROM for 6 movements of the lower extremity measured prior to the 2003-2004 English Premier League season. Player age, body size, dominant limb, and playing position were documented also. All lower-extremity muscle strain injuries were recorded prospectively during the competitive season, as was the total amount of time spent in training and games for each player.Soccer players sustaining a muscle strain injury in the hip flexors or knee flexors had lower pre- season ROM (p <= 0.05) in these muscle groups compared with uninjured players. Similar trends were observed for the remaining muscle groups, but all failed to reach statistical significance (p >= 0.05). Most significantly, soccer players with lower preseason ROM in the hip flexors and knee flexors had a statistically higher risk for a muscle strain injury to these muscle groups during a competitive season. Age, body size, limb dominance, and playing position were not significant intrinsic risk factors for the development of muscle strain injuries. Screening of flexibility for soccer players should be conducted during preseason, and flexibility training should be prescribed to players with reduced ROM to lower the risk of developing a muscle strain injury.
x.
The effects of six weeks of training on physical fitness and performance in teenage and mature top-level soccer playersBetween the first and second test session, all subjects followed six weeks of soccer-specific periodized training programme. There were no differences between groups at pre- and post-training trial for body mass, vertical jump height, average anaerobic power and VO2max (P>0.05). Body fat was significantly lower in YG before and after training program as compared to MG (P<0.05). Body mass and fat dropped significantly in both groups after training program (P<0.05). Furthermore, average anaerobic power and VO2max along with vertical jump height, were significantly improved in both groups (P<0.05) at post-training performance. Finally, the magnitude of change in VO2max was significanty superior in MG as compared to YG after training program (18.3 vs. 7.8%; P<0.05). The findings of the present study indicate that the trainability indices are not highly influenced by age in top-level soccer players.
x.
Physiologic Effects of Directional Changes in Intermittent Exercise in Soccer Players
The aim of the present study was to compare the physiologic impact of intermittent exercise in specific shuttle running (IS), which requires 180[degrees] directional changes, and traditional in-line (IL) running. Ten elite male adult soccer players performed different intermittent exercises according to their maximal aerobic velocity ([nu][latin capital V with dot above]O2max): 30-30 seconds at 100% (30 s of runs at 100% of [nu][latin capital V with dot above]O2max alternated with 30-s recovery period), 105%, and 110% of [nu][latin capital V with dot above]O2max with active recovery, 15-15 seconds at 105%, 110%, and 115% of [nu][latin capital V with dot above]O2max, and 10-10 seconds at 110%, 115%, and 120% of [nu][latin capital V with dot above]O2max with passive recovery. Each exercise was performed in the IL and IS format in a randomized order. Heart rate (HR) expressed in percentage of HR reserve (HRres), postexercise blood lactate concentration [La], and ratings of perceived exertion (RPE) were recorded. The different 30-30 seconds showed significantly higher HRres responses in IS compared with IL (p < 0.01). The [La] and RPE results indicated higher values in IS. In conclusion, the physiologic impact of specific IS is substantially higher than in traditional IL. The changes of direction induce an increase in the anaerobic metabolism solicitation and consequently create different responses compared with traditional IL running. This information can aid coaches in the design of intermittent training programs using classical (IL) or a specific form (IS) of running to induce different physiologic responses.
x.
Relationship Among Repeated Sprint Tests, Aerobic Fitness, and Anaerobic Fitness in Elite Adolescent Soccer Players
x.
Effect of a Single Dose of Caffeine Supplementation and Intermittent-interval Exercise on Muscle Damage Markers in Soccer Players
x.
Effect of soccer training on the running speed and the blood lactate concentration at the lactate minimum testx.
Avoidance motivation and choking under pressure in soccer penalty shootouts.The purpose of this study was to examine the relationships between shot valence, avoidance behavior, and performance in soccer penalty shootouts. Video analyses were conducted with all penalty shootouts ever held in the World Cup, the European Championships, and the UEFA Champions League (n = 36 shootouts, 359 kicks). Shot valence was assessed from the potential consequences of a shot outcome as follows: Shots where a goal instantly leads to victory were classified as positive valence shots and shots where a miss instantly leads to loss as negative valence shots. Avoidance behavior was defined as looking away from the goalkeeper or preparing the shot quickly (thus speeding up the wait). The results showed that avoidance behavior occurred more with negative valence shots than with positive shots and that players with negative valence shots performed worse than those with positive shots. Thus, avoidance motivation may help explain why professional athletes occasionally choke under pressure.
x.
A comparison of muscle strength and flexibility between the preferred and non-preferred leg in English soccer players
x.
Positional assessment and physical fitness characteristics of male professional soccer players in South Africa : sport scienceThe purpose of this study was to describe the physical fitness of professional soccer players in South Africa and assess the difference in fitness status between different playing positions. Professional soccer players (N = 140) from various clubs in the Premier Soccer League (PSL) in South Africa underwent a battery of tests assessing key physiological components during the first half of their competitive season. Players were separated into one of four primary playing positions (goalkeepers, GK, n = 16; defenders, DEF, n = 48; midfielders, MID, n = 46; forwards, FWD, n = 30) on the basis of their playing position and designated role within the team. Descriptive statistics (mean + SD) were calculated for the entire group and each position, and a one-way ANOVA was used to compare the positions for each of the physical tests. No differences were found between positions in age, flexibility, absolute vertical jump height, strength-endurance, acceleration and speed, or agility.
x.
Relationship Between the 20-m Multistage Shuttle Run Test and 2 Soccer-Specific Field Tests for the Assessment of
The aim of this study was to examine the relationship of 2 different field tests for the assessment of aerobic fitness in soccer players with the multistage 20-m test used for the evaluation of maximum oxygen uptake. Nineteen semi-professional male soccer players (age: 22.8 +/- 2.5 mean +/- SD) performed, under similar conditions, 3 field tests in a counterbalanced order 7 days apart. These tests were the multistage 20-m shuttle run test (MSRT), the Bangsbo test, and the Hoff test. Heart rate was recorded in all tests with telemetry, and the Borg scale was introduced at the end of exercise. Finally, 3-minute post-test lactate concentration was determined. Performance was 11.2 +/- 0.9 levels in the MSRT, 1,658.9 +/- 119.9 m in the Bangsbo test, and 1,798.2 +/- 125.9 m in the Hoff test. There was a significant correlation between the Hoff test and performance in the MSRT (r = 0.49, p < 0.05). The Bangsbo test was not associated with the MSRT score (r = 0.26, p > 0.05). The maximum heart rate achieved in the Bangsbo test was significantly lower compared with that in the MSRT and Hoff test (Bangsbo: 186.6 +/- 9.6, Hoff: 192 +/- 7.6, MSRT: 190.4 +/- 9.3 beats/min, p < 0.05). No difference was found in post-test lactate concentration among the 3 tests. In conclusion, the Hoff test can be used for the assessment of endurance in adult semi-professional soccer players. Coaches and teams could benefit from using the Hoff test that resembles soccer actions for the assessment of players' aerobic fitness.
x.
Genotype Distributions in Top-level Soccer Players: A Role for ACE? Since the ACE II genotype is associated with improved potential for endurance performance but with decreased training gains in muscle mass and strength, these findings together with previous results [37] support the notion that elite soccer players tend to have a power/strength oriented genotype.
x.
Nutrient intake and blood iron status of male collegiatex.
Analysis of High Intensity Activity in Premier League Soccer
x.
A Musculoskeletal Profile of Elite Female Soccer Players
x.
2009: Effects of Lower-Limb Plyometric Training on Body Composition, Explosive Strength, and Kicking Speed in Female Soccer PlayersHowever, the CG followed the regular soccer physical conditioning program, which was replaced by a plyometric program for PG. Neither CG nor PG performed weight training. Plyometric training took place 3 days a week for 12 weeks including jumps over hurdles, drop jumps (DJ) in stands, or horizontal jumps.It could be concluded that a 12-week plyometric program can improve explosive strength in female soccer players and that these improvements can be transferred to soccer kick performance in terms of ball speed. However, players need time to transfer these improvements in strength to the specific task. Regular soccer training can maintain the improvements from a plyometric training program for several weeks.
x.
Testosterone responsiveness to winning and losing experiences in female soccer playersIn many animal species including humans circulating androgen levels in males respond to social challenges. This response has been interpreted as an adaptive mechanism that helps the individuals to adjust their behavior to changes in social context. According to this hypothesis socially modulated androgen levels (e.g. increased levels in dominants and decreased levels in subordinates) would influence the subsequent expression of social behavior in a status-dependent fashion. This rationale is partially based on male physiology and therefore has been rarely investigated in females. Here, we investigated if a hormonal response to a social challenge that produces changes in status is also present in human females. We have collected saliva from and administered questionnaires to female soccer players of both teams playing the final match of the Portuguese Female soccer league. Samples were collected on a neutral day and on the day of the game both before and after the match.
x.
Perceptual and cognitive skill development in soccer: The multidimensional nature of expert performance.This study examined the relative contribution of visual, perceptual, and cognitive skills to the development of expertise in soccer. 137 elite and sub-elite players (aged 9-17 yrs) were assessed using a multidimensional battery of tests. Four aspects of visual function were measured: static and dynamic visual acuity; stereoscopic depth sensitivity; and peripheral awareness. Perceptual and cognitive skills were assessed via the use of situational probabilities, as well as tests of anticipation and memory recall. Stepwise discriminant analyses revealed that the tests of visual function did not consistently discriminate between skill groups at any age. Tests of anticipatory performance and use of situational probabilities were the best in discriminating across skill groups. Memory recall of structured patterns of play was most predictive of age. As early as age 9, elite soccer players demonstrated superior perceptual and cognitive skills when compared to their sub-elite counterparts. Implications for training perceptual and cognitive skill in sport are discussed.
x.
Ball-sport Endurance and Sprint Test (BEAST90): Validity and Reliability of a 90-Minute Soccer Performance TestThe aim of this study was to determine the validity and reliability of a 90-minute soccer performance test: Ball-sport Endurance and Sprint Test (BEAST90). Fifteen healthy male amateur soccer players participated and attended 5 testing sessions over a 10-day period to perform physiologic and soccer-specific assessments. This included familiarization sessions and 2 full trials of the BEAST90, separated by 7 days. The total 90-minute distance, mean percent peak heart rate (HRpeak), and estimated percent peak oxygen uptake of the BEAST90 were 8,097 +/- 458 m, 85 +/- 5% and 82 +/- 14%, respectively. Measures obtained from trial 1 and trial 2 were not significantly different (p > 0.05). Reliability of measures over 90 minutes ranged from 0.9-25.5% (% typical error). The BEAST90 protocol replicated soccer match play in terms of time, movement patterns, physical demands (volume and intensity), distances, and mean and HRpeak values, as well as having an aerobic load similar to that observed during a soccer match. Reproducibility of key physical measures during the BEAST90 were mostly high, suggesting good reliability. The BEAST90 could be used in studies that wish to determine the effects of training or nutritional interventions on prolonged intermittent physical performance.
x.
Comparative Study of Field and Laboratory Tests for the Evaluation of Aerobic Capacity in Soccer PlayersThe purpose of this study was to evaluate the maximal oxygen uptake (VO2max) values in soccer players as assessed by field and laboratory tests. Thirty-five elite young soccer players were studied (mean age 18.1 +/- 1.0 years, training duration 8.3 +/- 1.5 years) in the middle of the playing season. All subjects performed 2 maximal field tests: the Yo-Yo endurance test (T1) for the estimation of VO2max according to normogram values, and the Yo-Yo intermittent endurance test (T2) using portable telemetric ergospirometry; as well as 2 maximal exercise tests on the treadmill with continuous (T3) and intermittent (T4) protocols. The estimated VO2max values of the T1 test (56.33 ml[middle dot]kg-1[middle dot]min-1) were 10.5%, 11.4%, and 13.3% (p <= 0.05) lower than those of the T2 (62.96 ml[middle dot]kg-1[middle dot]min-1), T3(63.59 ml[middle dot]kg-1[middle dot]min-1) and T4 (64.98 ml[middle dot]kg-1[middle dot]min-1) tests, respectively. Significant differences were also found between the intermittent exercise protocols T1 and T3 (p <= 0.001) and the continuous exercise protocols T2 and T4 (p <= 0.001). There was a high degree of cross correlation between the VO2max values of the 3 ergospirometric tests (T2 versus T3, r = 0.47, p <= 0.005; T2versus T4, r = 0.59, p <= 0.001; T3 versus T4 r = 0.79, p <= 0.001). It is necessary to use ergospirometry to accurately estimate aerobic capacity in soccer players. Nevertheless, the Yo-Yo field tests should be used by coaches because they are easy and helpful tools in the training program setting and for player follow-up during the playing season.
x.
Prevention of anterior cruciate ligament injuries in soccer. A prospective controlled study of proprioceptive trainingAbstract Proprioceptive training has been shown to reduce the incidence of ankle sprains in different sports. It can also improve rehabilitation after anterior cruciate ligament (ACL) injuries whether treated operatively or nonoperatively. Since ACL injuries lead to long absence from sports and are one of the main causes of permanent sports disability, it is essential to try to prevent them. In a prospective controlled study of 600 soccer players in 40 semiprofessional or amateur teams, we studied the possible preventive effect of a gradually increasing proprioceptive training on four different types of wobble-boards during three soccer seasons. Three hundred players were instructed to train 20 min per day with 5 different phases of increasing difficulty. The first phase consisted of balance training without any balance board; phase 2 of training on a rectangular balance board; phase 3 of training on a round board; phase 4 of training on a combined round and rectangular board; phase 5 of training on a so-called BABS board. A control group of 300 players from other, comparable teams trained ldquonormallyrdquo and received no special balance training. Both groups were observed for three whole soccer seasons, and possible ACL lesions were diagnosed by clinical examination, KT-1000 measurements, magnetic resonance imaging or computed tomography, and arthroscopy. We found an incidence of 1.15 ACL injuries per team per year in the control group and 0.15 injuries per team per year in the proprioceptively trained group (P<0.001). Proprioceptive training can thus significantly reduce the incidence of ACL injuries in soccer players.
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Applied physiology of soccer.
Soccer is characterised as a high intensity, intermittent non-continuous exercise. Players cover approximately 10 km of ground per game, of which 8 to 18% is at the highest individual speed. In higher levels of competition there is a greater number of tackles and headings plus a greater percentage of the game is performed at maximum speed. The average aerobic energy yield during a national level game is around 80% of the individual maximum. Blood lactate concentration during a game averages 7 to 8 mmol/L. Because of a high energy yield most players have empty muscle glycogen stores at the end of the game, were hypohydrated and also have an increased body temperature. Soccer players of national and international standard have a maximal aerobic power of around 60 to 65 ml/kg/min, an above average anaerobic alactacid power, and a greater buffer capacity and muscle strength compared with untrained controls, yet seem to be less flexible.
x.
The biomechanics of soccer: A reviewThis review considers the biomechanical factors that are relevant to success in the game of soccer. Three broad areas are covered: (1) the technical performance of soccer skills; (2) the equipment used in playing the game; and (3) the causative mechanisms of specific soccer injuries. Kicking is the most widely studied soccer skill. Although there are many types of kick, the variant most widely reported in the literature is the maximum velocity instep kick of a stationary ball. In contrast, several other skills, such as throwing-in and goalkeeping, have received little attention; some, for example passing and trapping the ball, tackling, falling behaviour, jumping, running, sprinting, starting, stopping and changing direction, have not been the subject of any detailed biomechanical investigation. The items of equipment reviewed are boots, the ball, artificial and natural turf surfaces and shin guards. Little of the research conducted by equipment manufacturers is in the public domain; this part of the review therefore concentrates on the mechanical responses of equipment, player-equipment interaction, and the eff ects of equipment on player performance and protection. Although the equipment has mechanical characteristics that can be reasonably well quantified, the player-equipment interaction is more difficult to establish; this makes its efficacy for performance or protection difficult to predict. Some soccer injuries may be attributable to the equipment used. The soccer boot has a poor protective capability, but careful design can have a minor influence on reducing the severity of ankle inversion injuries. Performance requirements limit the scope for reducing these injuries; alternative methods for providing ankle stability are necessary. Artificial surfaces result in injury profiles diff erent from those on natural turf pitches. There is a tendency for fewer serious injuries, but more minor injuries, on artificial turf than on natural turf pitches. Players adapt to surface types over a period of several games. Therefore, changing from one surface to another is a major aetiological factor in surface-related injuries. Heading the ball could lead to long-term brain damage. Simulation studies suggest the importance of ball mass, ball speed and player mass in affecting the severity of impact. Careful instruction and skill development, together with the correct equipment, is necessary for young players. Most applications of biomechanical techniques to soccer have been descriptive experimental studies. Biomechanical modelling techniques have helped in the understanding of the underlying mechanisms of performance, although their use has been limited. It is concluded that there are still many features of the game of soccer that are amenable to biomechanical treatment, and many opportunities for biomechanists to make a contribution to the science of soccer.
x.
The incidence of ankle sprains in soccer.This study investigated the relationship between exposure time and ankle sprains in soccer. Forty-one teams (639 players) from four male senior soccer divisions at different levels of skill (divisions I-VI) were followed prospectively for 1 year. The exposure to soccer and the number of injuries per player were higher in higher divisions, but the injury incidence, percentage of ankle injuries and incidence of ankle injuries were the same at different levels of skill. Of all injuries 17 to 20% were ankle sprains and the incidence varied between 1.7 to 2.0 ankle injuries per 1,000 hours of exposure. Since players with previous ankle problems run an increased risk of reinjury we suggest that these players receive preventive advice.
x.
Energy demands in competitive soccer.In elite outfield players, the average work rate during a soccer match, as estimated from variables such as heart rate, is approximately 70% of maximal oxygen uptake (VO2 max). This corresponds to an energy production of approximately 5700 kJ (1360 kcal) for a person weighing 75 kg with a VO2 max of 60 ml kg-1 min-1. Aerobic energy production appears to account for more than 90% of total energy consumption. Nevertheless, anaerobic energy production plays an essential role during soccer matches. During intensive exercise periods of a game, creatine phosphate, and to a lesser extent the stored adenosine triphosphate, are utilized. Both compounds are partly restored during a subsequent prolonged rest period. In blood samples taken after top-class soccer matches, the lactate concentration averages 3-9 mM, and individual values frequently exceed 10 mM during match-play. Furthermore, the adenosine diphosphate degradation products--ammonia/ammonium, hypoxanthine and uric acid--are elevated in the blood during soccer matches. Thus, the anaerobic energy systems are heavily taxes during periods of match-play. Glycogen in the working muscle seems to be the most important substrate for energy production during soccer matches. However, muscle triglycerides, blood free fatty acids and glucose are also used as substrates for oxidative metabolism in the muscles.
x.
Aerobic endurance training improves soccer performanceConclusion: Enhanced aerobic endurance in soccer players improved soccer performance by increasing the distance covered, enhancing work intensity, and increasing the number of sprints and involvements with the ball during a match.
x.
Anthropometric and physiological predispositions for elite soccerThis review is focused on anthropometric and physiological characteristics of soccer players with a view to establishing their roles within talent detection, identification and development programmes. Top-class soccer playershave to adapt to the physical demandsof the game, which are multifactorial. Players may not need to have an extraordinary capacity within any of the areas of physical performance but must possess a reasonably high level within all areas. This explains why there are marked individual differences in anthropometric and physiological characteristics among top players. Various measurements have been used to evaluate specific aspects of the physical performance of both youth and adult soccer players.The positional role of a player is related to his or her physiological capacity. Consequently, fitness profiling can generate a useful database against which talented groups may be compared. No single method allows for a representative assessment of a player"s physical capabilities for soccer. Weconclude that anthropometric and physiological criteria do have a role as part of a holistic monitoring of talented young players.
x.
Strength and endurance of elite soccer playersPurpose: The major purpose of the present study was to examine whether there exists a relationship between preseasonal physiological tests and performance results in the soccer league. Further, it investigated maximal oxygen uptake and maximal strength in proportion to body mass for soccer players. A secondary aim was to establish some normative data of Norwegian elite soccer players.
Methods: Two teams from the Norwegian elite soccer league participated in the study.
Results/Conclusion: The present study supports previous investigations indicating a positive relationship between maximal aerobic capacity, physical strength, and performance results in the elite soccer league.
LEFTOFF
x.
Comparison of Various Exercise Tests with Endurance Performance during Soccer in Professional Players x.
Energetics of high-intensity exercise (soccer) with particular reference to fatigueSoccer entails intermittent exercise with bouts of short, intense activity punctuating longer periods of low-level, moderate-intensity exercise. High levels of blood lactate may sometimes be observed during a match but the active recovery periods at submaximal exercise levels allow for its removal on a continual basis. While anaerobic efforts are evident in activity with the ball and shadowing fast-moving opponents, the largest strain is placed on aerobic metabolism. On average, competitive soccer corresponds to an energy expenditure of about 75% maximal aerobic power. The energy expenditure varies with playing position, being highest among midfield players. Muscle glycogen levels can be reduced towards the end of a game, the level of reduction being reflected in a decrease in work rate. Blood glucose levels are generally well-maintained, although body temperature may rise by 2 C even in temperate conditions. The distance covered by players tends to under-reflect the energy expended. Unorthodox modes of motion - running backwards and sideways, accelerating, decelerating and changing direction- accentuate the metabolic loading. These are compounded by the extra requirements for energy associated with dribbling the ball and contesting possession. The overall energy expended is extreme when players are required to play extratime in tournaments. Training, nutritional and tactical strategies may be used to reduce the effects of fatigue that may occur late in the game.
x.
Match performance of high-standard soccer players with special reference to development of fatiguex.
Knee Joint Laxity and Neuromuscular Characteristics of Male and Female Soccer and Basketball Playersx.
Talent identification and development in soccerIn this review, we attempt to integrate the main research findings concerned with talent identification and development in soccer. Research approaches in anthropometry, physiology, psychology and sociology are considered and, where possible, integrated. Although some progress has been made in identifying correlates of playing success, it appears that no unique characteristics can be isolated with confidence. Both biological and behavioural scientists have indicated a strong genetic component in performance of sports such as soccer; nevertheless, the influence of systematic training and development programmes should not be underestimated. Weconclude that the sport and exercise sciences have an important support role in the processes of identifying, monitoring and nurturing talented soccer players towards realizing their potential.
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Hamstring injury occurrence in elite soccer players after preseason strength training with eccentric overloadx.
Visual search strategy, selective attention, and expertise in soccer.This research examined the relationship between visual search strategy, selective attention, and expertise in soccer. Experienced (n = 12) and less experienced (n = 12) soccer players moved in response to filmed offensive sequences. Experiment 1 examined differences in search strategy between the two groups, using an eye movement registration system. Experienced players demonstrated superior anticipation in 3-on-3 and 1-on-1 soccer simulations. There were no differences in search strategy in 3-on-3 situations. In 1-on-1 simulations, the experienced players had a higher search rate, involving more fixations of shorter duration, and fixated for longer on the hip region, indicating that this area was important in anticipating an opponent's movements. Experiment 2 examined the relationship between visual fixation and selective attention, using a spatial occlusion approach. In 3-on-3 situations, masking information "pick up" from areas other than the ball or ball passer had a more detrimental effect on the experienced players' performances, suggesting differences in selective attention. In 1-on-1 situations, occluding an oncoming dribbler's head and shoulders, hips, or lower leg and ball region did not affect the experienced players' performances more than the less experienced group. The disparities in search strategy observed in Experiment 1 did not directly relate to differences in information extraction. Experiment 3 used concurrent verbal reports to indicate where participants extracted information from while viewing 3-on-3 sequences. Experienced players spent less time attending to the ball or ball passer and more time on other areas of the display. Findings highlight the advantages of integrating eye movements with more direct measures of selective attention.
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The frequency of muscle tightness and injuries in soccer players.One hundred-eighty players in a male, senior soccer division were examined for past injuries, persisting symptoms from past injuries, and muscular tightness in the lower extremities. Soccer players were in general less flexible than a group of nonplayers of the same age (n = 86). No correlation was found between past injuries and existing muscle tightness. Sprains of the lower extremity, especially of knees and ankles, predominated among the injuries. Persistent instability symptoms were common sequels to knee and ankle injuries. It is proposed that intensive care of acute injuries will improve the late results.
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Physiology of Soccer: An Updatex.
Home advantage in soccer: a retrospective analysis.The existence of home advantage has been established for all major professional team sports in England and North America. The advantage was found to be greatest in soccer, with the home team currently obtaining about 64% of all points gained in the English Football League. Home advantage has changed very little since the formation of the League in 1888 and there are only small variations between the four Divisions of the League. The advantage is less marked in local derbies, in the FA Cup and in nonprofessional competitions. It is greater in the European Cup and increases as the stages of the competition progress. The allocation of three points, instead of two, for a win in the Football League has not changed home advantage, but its effect has been greatly reduced in the GM Vauxhall Conference where an away win gains more points than a home win. The statistical evidence suggests that crowd support and travel fatigue contribute less to home advantage in soccer than do the less easily quantifiable benefits of familiarity with conditions when playing at home. Further possible explanations for the advantage are discussed in the light of findings in other sports.
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The influence of intermittent high-intensity shuttle running and fluid ingestion on the performance of a soccer skillThe aim of this study was to examine the effect of intermittent high-intensity shuttle running and fluid ingestion on the performance of a soccer skill. Nine semi-professional soccer players volunteered to participate in the study. Their mean (sx) age, body mass and maximal oxygen uptake were 20.2 +/- 0.4 years, 73.2 +/- 1.8 kg and 59.1 +/- 1.3 ml.kg-1.min-1 respectively. The players were allocated to two randomly assigned trials: ingesting or abstaining from fluid intake during a 90 min intermittent exercise protocol (Loughborough Intermittent Shuttle Test:LIST).This test was designed to simulate the minimum physical demands faced by soccer players during a game. Before and immediately after performance of the test,the players completed a soccer skill test and a mental concentration test. Performance of the soccer skill test after the "no-fluid" trial deteriorated by 5% (P < 0.05),but was maintained during the fluid trial. Mean heart rate, perceived exertion, serum aldosterone, osmolality, sodium and cortisol responses during the test were higher (P < 0.05) in the "no-fluid" trial than in the fluid trial. The results of this study suggest that soccer players should consume fluid throughout a game to help prevent a deterioration in skill performance.
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ological and technical aspects of "6-a-side" soccer drillsx.
Soccer Fatigue, Sprinting and Hamstring Injury Risk x.
Indicators of iron status in elite soccer players during the sports seasonx.
The Comparative Study on the Supplement Use Habits of Korean Professional Soccer Players and Non-Athletic Males. This study was performed to compare nutritional supplementation habits for Korean professional soccer players with those for the non-athletic male adults. Information about prevalence and kinds of supplements taken, information sources, nutrition knowledge were collected. Data were obtained from 53 football players working for Korean professional football clubs and 44 non-athletic males, who answered a list of questionnaires which had been prepared in advance. The prevalence of supplement use in the soccer player group (96%) was strikingly higher than in the nonathletic male group (34%). Vitamins were taken most frequently, followed by red ginseng, multivitamin, Chinese medicine and amino acids supplements in the soccer player group, with each player taking 2.96 kinds of supplements in average. Multivitamin was the most popular supplement in the non-athletic male group. The major reason for taking supplements was not to feel and recover from fatigue in both groups. It appeared that the non-athletic males started to use supplements mostly by recommendation of friends or colleagues. Meanwhile, soccer players took supplements on their needs, with half of them (50.1%) provided with nutrition information. The most important information source was coaches for soccer players group, and mass media for the non-athletic male group. The average scores of soccer players group on basic nutrition and athletic nutrition were lower than the respective values of the non-athletic males. Among the soccer players, 68% had taken more than 3 kinds of supplements during the last year; nonetheless, more than half could not perceive the effectiveness of the supplements. Our results show that supplementation practices were widespread in soccer players, and suggest that nutrition education for proper use of supplements and overall health care is needed for soccer players.
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Effects of cold-water immersion on physical performance between successive matches in high-performance junior male soccer players.In this study, we investigated the effect of water immersion on physical test performance and perception of fatigue/recovery during a 4-day simulated soccer tournament. Twenty high-performance junior male soccer players (age 15.9 +/- 0.6 years) played four matches in 4 days and undertook either cold-water immersion (10 +/- 0.5 degrees C) or thermoneutral water immersion (34 +/- 0.5 degrees C) after each match. Physical performance tests (countermovement jump height, heart rate, and rating of perceived exertion after a standard 5-min run and 12 x 20-m repeated sprint test), intracellular proteins, and inflammatory markers were recorded approximately 90 min before each match and 22 h after the final match. Perceptual measures of recovery (physical, mental, leg soreness, and general fatigue) were recorded 22 h after each match. There were non-significant reductions in countermovement jump height (1.7-7.3%, P = 0.74, eta(2) = 0.34) and repeated sprint ability (1.0-2.1%, P = 0.41, eta(2) = 0.07) over the 4-day tournament with no differences between groups. Post-shuttle run rating of perceived exertion increased over the tournament in both groups (P < 0.001, eta(2) = 0.48), whereas the perceptions of leg soreness (P = 0.004, eta(2) = 0.30) and general fatigue (P = 0.007, eta(2) = 0.12) were lower in the cold-water immersion group than the thermoneutral immersion group over the tournament. Creatine kinase (P = 0.004, eta(2) = 0.26) and lactate dehydrogenase (P < 0.001, eta(2) = 0.40) concentrations increased in both groups but there were no changes over time for any inflammatory markers. These results suggest that immediate post-match cold-water immersion does not affect physical test performance or indices of muscle damage and inflammation but does reduce the perception of general fatigue and leg soreness between matches in tournaments.
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Muscle Activation During Side-Step Cutting Maneuvers in Male and Female Soccer Athletesx.
2009: Interlimb Coordination, Strength, and Power in Soccer Players Across the Lifespanx.
LACTATE AND VENTILATORY THRESHOLDS REFLECT THE
TRAINING STATUS OF PROFESSIONAL SOCCER PLAYERS
WHERE MAXIMUM AEROBIC POWER IS UNCHANGEDx.
2008: The anaerobic endurance of elite soccer players improved following a high intensity interval training intervention in the 8-week conditioning programx.
Strength training effects on physical performance and serum hormones in young soccer playersx.
Preseason Physiological Profile of Soccer and Basketball Players in Different Divisionsx.
Comparison of Two Twelve Week Off-Season Combined Training Programs on Entry Level Collegiate Soccer Players' performanceOlympic-style lifts (OSL) and plyometric exercises (PE) are frequently combined with traditional resistance training (TRT) to improve athletic performance. The goal of this study was to directly compare the performance effect of TRT (30 minutes) combined with either OSL or nondepth-jump PE (15 minutes) on entry level competitive collegiate athletes. Ten female and 5 male competitive soccer players, divided into 2 groups, completed 12 weeks of triweekly training during their off-season. Countermovement vertical jump, 4 repetition maximum squat, 25-m sprint, and figure-8 drill on a 5-dot mat were conducted pre-, mid-, and postintervention. Significant improvements were made by both groups in each performance parameter over the 12-week period (p < 0.05), with no significant differences found between the training groups. Although these training modalities may achieve their results through slightly different mechanisms, the performance-related improvements may not be significantly different for entry-level collegiate athletes with little resistance training experience.
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Acute effects of static stretching duration on isokinetic peak torque production of soccer playersx.
The Anaerobic Endurance of Elite Soccer Players Improved After a High-Intensity Training Intervention in the 8-Week Conditioning Programx.
Comparison of Selected Warm-up Procedures in Young Female Soccer Playersx.
Seasonal variation in fitness variables in professional soccer playersBackground. There have been many studies on soccer, but few evaluations of the physiological function of professional soccer players. The aim of this work was to evaluate seasonal variation - from September to February - in anthropometric and physiological variables in a Spanish professional soccer team (n=15). Methods. Anthropometric measurements were obtained following the standardised techniques adopted by the International Society for the Advancement of Kinanthropometry (ISAK). A maximal treadmill test with breath-by-breath gas analysis was carried out to evaluate the aerobic condition and a Jump test was used to measure muscle performance and strength in the lower limbs. Results. There were no significant variations in body mass, although a statistically significant decrease (p<0.05) in fat percentage and sum of six skinfolds was observed. The somato-type (Heath-Carter) was mesomorphic without any change observed throughout the season. The mean VO2max in the first test (65.5 ml.kg-1.min-1) had not changed by the second one (66.4 ml.kg-1.min-1). There were no significant differences in maximal heart rate (185 vs 185 beats.min-1) and treadmill speed at VO2max (16.1 vs 15.8 km.h-1). At the anaerobic threshold, there were significant differences (p<0.05) in speed (12.4 vs 13.1 km.h-1) and heart rate (164 vs 168 beats.min-1) as the season progressed. When the data were expressed as a percentage of maximal values obtained, we observed that the speed in the first test was 77 and 83% in the second test. For heart rate, values were 89 and 91%, and for oxygen uptake 77 and 79%. The Jump test did not show any significant change during the season. Conclusions. We can conclude from these results that professional soccer players have good fitness from the beginning of the Spanish League - with a high V.O2max - and the changes observed depend on the initial values.
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Strong correlation of maximal squat strength with sprint performance and vertical jump height in elite soccer playersx.
Isokinetic Strength and Anaerobic Power of Elite, Subelite and Amateur French Soccer Players x.
Physiological characteristics of elite soccer players.Soccer is one of the most popular sports in the world. There is still much uncertainty and debate surrounding its physiological requirements because emphasis is on skills to the neglect of fitness, conservative training methods and the difficulty of studying the sport scientifically. The frequently found values for total distance covered in a game of about 10 km and an above-average, though not outstanding, maximum oxygen uptake of 60 ml/kg/min suggest a moderate overall aerobic demand. A comparison of top teams and players with less able participants indicates that the components of anaerobic fitness-speed, power, strength and the capacity of the lactic acid system may differentiate better between the 2 groups. Generally, there is a reduction in the level of activity in the second half of games compared with the first. There is some evidence that increased aerobic fitness may help counteract this. Progressively lower muscle glycogen stores are one likely cause of reduction in activity, and nutrition also appears to be a key factor in minimising performance deterioration, both in terms of overall diet and, more particularly, the ingestion of carbohydrates immediately before, during and after a game. There are evolutionary trends in the sport such as greater frequency of games, changes in the roles of players, and new strategies and tactics which are placing increasing demands on the all-round fitness of players. Many studies indicate scope for improvement in player fitness. The challenge for coaches and players is to meet these fitness requirements without sacrificing the skill work which makes the sport unique.
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Muscle Flexibility as a Risk Factor for Developing Muscle Injuries in Male Professional Soccer Players A Prospective Studyx.
Soccer specific aerobic endurance trainingx.
Does a major knee injury definitely sideline an elite soccer player?Injuries occurring in three Swedish elite soccer teams were analyzed during 1 year. A total of 49 of 64 players (75%) sustained 85 injuries. The incidence of injury during games was 13 injuries per 1000 hours, while the incidence during training was 3 injuries per 1000 hours. Twenty percent of the injuries required hospital facili ties. The majority of the traumatic injuries (93%) were to the lower extremities, with one third of the total injuries occurring in the knee. Overuse injuries ac counted for 35% of all injuries and occurred mainly during preseason training and at the end of each sea son. Conversely, the majority of traumatic injuries oc curred during games, equally distributed between the first and second halves with a predominance toward the end of each half. The position of the player within the team did not influence injury rate. The referee considered 28% of the traumatic injuries to be caused by violation of existing rules. Thirty-four percent of the injuries were major, causing more than 1 month of absence from training and/or games. Eleven knee in juries required surgical intervention revealing seven rup tured ACLs, of which three were chronic. At followup, 9 to 18.5 months after injury, 4 of 12 players with major knee injuries had returned to play at the elite level. The others had either been transferred to lower divisions or were still in rehabilitation.
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2000: Investigation of anthropometric and work-rate profiles of elite South American international soccer players.BACKGROUND: The aim of the current investigation was to determine the movement profiles of elite South American soccer players during international competition and examine the relationship between anthropometric profile and work-rate variables. METHODS: Seventeen full-time professional soccer players were filmed while competing for their countries. Anthropometric profiles were obtained for eleven of these players. Six full-time professional players from the English Premier League were also filmed for comparative purposes. RESULTS: The South American international players covered significantly less (p<0.05) total distance during match-play than English Premier League players (International, 8638+/-1158 m; English Premier League, 10104+/-703 m). The total distance covered during the second half of the game was significantly reduced (p<0.05) compared to the first half distance for both groups of players (mean+/-SD first half 4605+/-625 m; mean+/-SD second half 4415+/-634 m). The data for both groups of players were combined to evaluate positional differences in the workrate profile. Midfield players covered a significantly greater (p<0.05) distance than forward players (midfield, 9826+/-1031 m; forwards, 7736+/-929 m) and defenders covered a greater (p<0.05) distance jogging backwards than forward players (defenders, 276+/-155 m; forwards, 68+/-25 m). Forwards sprinted a greater distance (p<0.05) than defensive players (defenders, 231+/-142 m; forwards, 557+/-142 m). Mean somatotype was a balanced mesomorph (2-5 1/2-2). Body mass and muscle mass was related to the total distance covered (r=0.43, r=0.53, p<0.05). CONCLUSIONS: Based on these data, it seems that an individual's work-rate profile is dependent upon the type of competition and the playing position. Relationships between anthropometric profile and work-rate are complex due to the interaction between the variables that determine work-rate.
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Muscle glycogen and diet in elite soccer playersx.
Women's soccer injuries in relation to the menstrual cycle and oral contraceptive useWomen's soccer injuries in relation to the menstrual cycle and oral contraceptive use. Med. Sci. Sports Exerc, Vol. 21, No. 2, pp. 126-129, 1989. During 1984, 86 women soccer players answered detailed questionnaires concerning contraceptive use, menstruation data, premenstrual and menstrual symptoms, and data concerning soccer activities including injuries. This prospective study showed that women soccer players were more susceptible to traumatic injuries during the premenstrual and menstrual period compared to the rest of the menstrual cycle (P < 0.05), especially among players with premenstrual symptoms such as irritability/irascibility, swelling/discomfort in the breasts, and swelling/congestion in the abdomen. It was also found that women using contraceptive pills had a lower rate of traumatic injuries (P < 0.05) compared to women who were not on the Pill. The results can be explained by the fact that oral contraceptives ameliorate some symptoms of the premenstrual and menstrual period which might also affect coordination and hence the risk of injury.
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Physiological and performance effects of generic versus specific aerobic training in soccer players.The aim of this study was to compare the effects of specific (small-sided games) vs. generic (running) aerobic interval training on physical fitness and objective measures of match performance in soccer. Forty junior players were randomly assigned to either generic (n=20) or specific (n=20) interval training consisting of 4 bouts of 4 min at 90-95 % of maximum heart rate with 3 min active rest periods, completed twice a week. The following outcomes were measured at baseline (Pre), after 4 weeks of pre-season training (Mid), and after a further 8 weeks of training during the regular season (Post): maximum oxygen uptake, lactate threshold (Tlac), running economy at Tlac, a soccer-specific endurance test (Ekblom's circuit), and indices of physical performance during soccer matches (total distance and time spent standing, walking, and at low- and high-intensity running speed). Training load, as quantified by heart rate and rating of perceived exertion, was recorded during all training sessions and was similar between groups. There were significant improvements in aerobic fitness and match performance in both groups of soccer players, especially in response to the first 4 weeks of pre-season training. However, no significant differences between specific and generic aerobic interval training were found in any of the measured variables including soccer specific tests. The results of this study showed that both small-sided games and running are equally effective modes of aerobic interval training in junior soccer players.
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Surface-related injuries in soccer.The review of the effects of artificial turf and natural grass on surface-related traumatic injuries in soccer suggests that surfaces with artificial turf produce more abrasion injuries than surfaces with natural grass. Most authors report no significant difference in injury frequencies for the number of traumatic injuries. However, some authors report fewer traumatic injuries on artificial turf, especially after a period of adaptation on the artificial turf. A difference in injury pattern and injury mechanism when playing on different types of surfaces has been suggested, as well as an increased injury risk for frequent alternating between different playing surfaces. The relationship between knee and ankle injuries and the fixation of the foot to the ground is not yet evaluated in soccer. In American football, the severity and incidence of knee and ankle injuries were reported to be significantly lower when using shoes with lower friction properties. However, in American football severe injuries typically occur in collision situations often independent of the surface. Soccer is characterised by sprinting, stopping, cutting and pivoting situations, where shoe-surface relations are essential and frictional resistance must be within an optimal range. Future research should address this compromise between performance and protection.
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A physiological evaluation of professional soccer players.The purpose of this study was to evaluate the physiological functions of a professional soccer team in the North American Soccer League (NASL). Eighteen players were evaluated on cardiorespiratory function, endurance performance, body composition, blood chemistry, and motor fitness measures near the end of their competitive season. The following means were observed: age, 26 yrs; height, 176 cm; weight 75.5 kg; resting heart rate, 50 beats/min; maximum heart rate (MHR), 188 beats/min; maximum oxygen intake (VO2 max), 58.4 ml/kg-min-1; maximum ventilation (VEmax BTPS), 154 L/min; body fat, 9.59%; 12-min run, 1.86 miles; and Illinois agility run, 15.6 secs. Results on resting blood pressure, serum lipids, vital capacity, flexibility, upper body strength, and vertical jump tests were comparable to values found for the sedentary population. Comparing the results with previously collected data on professional American Football backs indicated that the soccer players were shorter; lighter in body weight; higher in VO2 max (4 ml/kg-min-1) and body fat (1.8%); and similar in MHR, VE max, and VC. The 12-min run scores were similar to the initial values observed for the 1970 Brazilian World Cup Team. The agility run results were superior to data collected from other groups. Their endurance capabilities, agility, and low percent of body fat clearly differentiate them from the sedentary population and show them to be similar to that of professional American football backs.
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Soccer players under regular training show oxidative stress but an improved plasma antioxidant statusPhysical activity is known to induce oxidative stress in individuals subjected to intense exercise. In this study, we investigated the lipoprotein profile and the plasma antioxidant status in a group of soccer players engaged in a regular training programme. As was expected for aerobic exercise, high-density lipoprotein-cholesterol (HDL-C) and HDL3-C levels were significantly increased in the sportsmen (P < 0.05). Total plasma antioxidant capacity was 25% higher in sportsmen than in controls (P < 0.005). Accordingly, plasma hydrosoluble antioxidant levels (ascorbic acid and uric acid) were found to be significantly elevated in the soccer players (P < 0.005). In addition, these subjects showed high concentrations of a-tocopherol in plasma compared with controls (P < 0.005). Furthermore, an increase in plasma superoxide dismutase activity was also observed in relation to exercise (P < 0.01). The elevation in plasma activities of antioxidant enzymes and the higher levels of free radical scavengers of low molecular mass may compensate the oxidative stress caused by physical activity. High levels of high-density lipoprotein in plasma may offer additional protection by inhibiting low-density lipoprotein oxidation and thus liposoluble antioxidant consumption. Therefore, soccer players under regular training show an improved plasma antioxidant status in comparison to sedentary controls.
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Fatigue in soccer: A brief reviewx.
The Loughborough Intermittent Shuttle Test: A field test that simulates the activity pattern of soccerThe aims of this study were to describe and determine the test-retest reliability of an exercise protocol, the Loughborough Intermittent Shuttle Test (the LIST), which was designed to simulate the activity pattern characteristic of the game of soccer. The protocol consisted of two parts: Part A comprised a fixed period of variable-intensity shuttle running over 20 m; Part B consisted of continuous running, alternating every 20 m between 55% and 95% VO2max, until volitional fatigue. Seven trained games players (age 21.5 +/- 0.9 years, height 182 +/- 2 cm, body mass 80.1 +/- 3.6 kg, VO2max 59.0 +/- 1.9 ml kg-1 min-1; mean sx ) performed the test on two occasions (Trial 1 and Trial 2), at least7 days apart, to determine the test-retest reliability of the sprint times and running capacity. The physiological and metabolic responses on both occasions were also monitored. The participants ingested water ad libitum during the first trial, and were then prescribed the same amount of water during the second trial. The 15 m sprint times during Trials 1 and 2 averaged 2.42 +/- 0.04 s and 2.43 +/- 0.04 s, respectively. Run time during Part B was 6.3 +/- 2.0 min for Trial 1 and 6.1 +/- 1.3 min for Trial 2. The 95% limits of agreement for sprint times and run times during Part B were -0.14 to 0.12 s and -3.19 to 2.16 min respectively. There were no differences between trials for heart rate, rating of perceived exertion, body mass change during exercise, or blood lactate and glucose concentrations during the test. Thus, we conclude that the sprint times and the Part B run times were reproducible within the limits previously stated. In addition, the activity pattern and the physiological and metabolic responses closely simulated the match demands of soccer.
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Isokinetic Torque Levels for Knee Extensors and Knee Flexors in Soccer Players x.
Creatine supplementation and sprint performance in soccer playersx.
Muscle fatigue induced by exercise simulating the work rate of competitive soccerx.
Peak torque of quadriceps and hamstring muscles in basketball and soccer players of different divisions.Basketball and soccer are two games with different training and playing procedures. The purpose of this study was to examine the maximal voluntary peak torques of the quadriceps and hamstring muscles, and the torque ratio between these muscle groups in basketball players (n = 61) and soccer players (n = 51) participating in teams of different divisions. Isokinetic peak torques were measured using the Cybex II isokinetic dynamometer at 60 and 180 degrees.s-1. Basketball players of the national team produced higher peak torque values of quadriceps muscles than the other basketball players of different divisions (p < 0.05 to p < 0.001). Hamstring peak torques of the national basketball team were significantly higher the only velocities measured compared with the players from division II and IV (p < 0.05). Peak torque values of quadriceps muscles relative to body weight were significantly higher in the national basketball team compared with basketball players from division I. No significant differences were found in peak torque values of quadriceps and hamstring muscles within the different basketball and soccer divisions. Peak torque expressed in absolute terms was significantly higher in basketball players than in soccer players (p < 0.05 to p < 0.001). However, these differences were not significant when the strength of quadriceps and hamstring muscles was expressed relative to body weight. The H/Q ratio did not differ either ditto among the different divisions of basketball and soccer players. Based on the data obtained in this study, we concluded that the subjects' body weight have a decisive effect on the production of peak torque values of quadriceps and hamstring muscles in basketball and soccer players. Furthermore that the playing in different divisions, as well as participating in different sports, i.e. basketball or soccer, have surprisingly small effects on the peak isokinetic torque production of the quadriceps and hamstring muscles.
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Specificity of acceleration, maximum speed and agility in professional soccer playersHigh-speed actions are known to impact soccer performance and can be categorized into actions requiring maximal speed, acceleration, or agility. Contradictory findings have been reported as to the extent of the relationship between the different speed components. This study comprised 106 professional soccer players who were assessed for 10-m sprint (acceleration), flying 20-m sprint (maximum speed), and zigzag agility performance. Although performances in the three tests were all significantly correlated (p , 0.0005), coefficients of determination (r2) between the tests were just 39, 12, and 21% for acceleration and maximum speed, acceleration and agility, and maximum speed and agility, respectively. Based on the low coefficients of determination, it was concluded that acceleration, maximum speed, and agility are specific qualities and relatively unrelated to one another. The findings suggest that specific testing and training procedures for each speed component should be utilized when working with elite players.
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Effects of Hyperhydration on Total Body Water, Temperature Regulation and Performance of Elite Young Soccer Players in a Warm Climate x.
Outcome Uncertainty and Attendance Demand in Sport: The Case of English Soccer, by David Forrest and Robert Simmons We test whether attendances in team sports respond positively to the amount of uncertainty of the outcome between the competing teams in a match. Our results show that admissions at English soccer matches relate positively to the quality of teams involved and negatively to a measure of the relative win probabilities of the competing teams. The uncertainty measure is derived from a model of the betting market which corrects for specific biases tested for and identified in the odds in our data set. Although supporters appear to favour an uncertainty of outcome, a greater quality of strength across clubs may still yield a fall in aggregate attendance because of the extent to which home field advantage generates an uneven contest between similarly strong teams.
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Physical Demands during an Elite Female Soccer Game: Importance of Training Statusx.
Preliminary results on mood state, salivary testosterone:cortisol ratio and team performance in a professional soccer teamx.
Endurance and Strength Training for Soccer Players: Physiological Considerationsx.
Injuries in high-skilled and low-skilled soccer: a prospective study.Fifty-five male soccer players organized in three teams, one high and two lower ranking, were followed prospectively during 1 year to register the rate, type and severity of injuries in highly skilled and low-skilled players. The injury rate of the low-skilled players was significantly higher than that of the better players. The reason for this is that low-skilled players play in more competitions. and this is where injuries tend to occur. When we stratified on game/practice, the low-skilled players' excess risk disappeared and no difference was found in the severity of injuries. Different ways of collecting data in epidemiological studies of soccer are discussed and it is concluded that the most precise and accurate collection of data can only be obtained by direct supervision and examination of soccer players in the field.
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Physical Fitness, Injuries, and Team Performance in Soccerx.
Fluid replacement requirements in soccer.Soccer is an endurance sport that consists of moderate activity levels interspersed with intermittent high-intensity bursts, leading to high rates of metabolic heat production. Even when the weather is cold, significant sweat loss will occur, leading to a degree of dehydration which impairs exercise performance. Fluid intake before and during the game will provide water to reduce the degree of dehydration and can also supply carbohydrate to supplement the body's limited carbohydrate stores. Dilute carbohydrate-electrolyte drinks are most effective for rehydration. The optimum formulation will vary between individuals and will also depend on climatic conditions. Players should be encouraged to experiment with fluid intake during training to identify the type of drink and the amount and frequency of drinks that best meet their needs.
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Protein requirements of soccer.Although the physical demands of soccer have been studied frequently over the years, there has been little attention to the dietary protein needs of soccer players. Recent data from both moderate-intensity, prolonged (endurance) and heavy-resistance (strength) exercise studies indicate that the current recommendations (0.8 g per kg body mass per day) for protein intake are probably suboptimal for individuals who are chronically active. Endurance athletes need more dietary protein than sedentary individuals to maintain an auxiliary fuel source which appears to become increasingly important as exercise is prolonged. Strength athletes can also benefit from a greater protein intake than is currently recommended because it appears that, in combination with heavy-resistance training, it can provide an enhanced stimulus for muscle development. Soccer is a high-intensity, intermittent activity which requires aspects of both strength and endurance over a period of 90 min. As a result, soccer players would be likely to benefit from protein intakes above current recommendations not only because of their potential to enhance strength, but also to provide a supply of amino acids for any increased amino acid oxidation that may occur during training and in competition. Based on the related exercise studies completed to date, it appears that a protein intake of 1.4-1.7 g kg-1 day-1 should be adequate for soccer players. Assuming free access to a wide variety of foods, this protein intake can be easily obtained by most soccer participants. Individuals at greatest risk of falling short of this intake include those who are growing (especially children in developing countries where suboptimal protein intake may be common) or those who consume proteins of lower quality. Although diets high in protein are frequently condemned because of possible kidney problems, it appears these concerns have been over-emphasized. There is no evidence that protein intakes in the range recommended will cause healthy individuals any concerns.
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Muscle and Blood Metabolites during a Soccer Game: Implications for Sprint Performancex.
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Effects of Differential Stretching Protocols During Warm-Ups on High-Speed Motor Capacities in Professional Soccer PlayersThe purpose of this study was to examine the effects of different modes of stretching within a pre-exercise warm-up on high-speed motor capacities important to soccer performance. Eighteen professional soccer players were tested for countermovement vertical jump, stationary 10-m sprint, flying 20-m sprint, and agility performance after different warm-ups consisting of static stretching, dynamic stretching, or no stretching. There was no significant difference among warm-ups for the vertical jump: mean +/- SD data were 40.4 +/- 4.9 cm (no stretch), 39.4 +/- 4.5 cm (static), and 40.2 +/- 4.5 cm (dynamic). The dynamic-stretch protocol produced significantly faster 10-m sprint times than did the no-stretch protocol: 1.83 +/- 0.08 seconds (no stretch), 1.85 +/- 0.08 seconds (static), and 1.87 +/- 0.09 seconds (dynamic). The dynamic- and static-stretch protocols produced significantly faster flying 20-m sprint times than did the nostretch protocol: 2.41 +/- 0.13 seconds (no stretch), 2.37 +/- 0.12 seconds (static), and 2.37 +/- 0.13 seconds (dynamic). The dynamic-stretch protocol produced significantly faster agility performance than did both the no-stretch protocol and the staticstretch protocol: 5.20 +/- 0.16 seconds (no stretch), 5.22 +/- 0.18 seconds (static), and 5.14 +/- 0.17 seconds (dynamic). Static stretching does not appear to be detrimental to high-speed performance when included in a warm-up for professional soccer players. However, dynamic stretching during the warm-up was most effective as preparation for subsequent high-speed performance.
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Effect of glucose polymer ingestion on glycogen depletion during a soccer match.The effect on muscle glycogen utilization of drinking a glucose polymer solution before and during a soccer match was studied. Ten male soccer players were divided into two groups balanced both for playing position and between the two teams. Five players on the experimental team (ET) ingested 0.5 L of 7% glucose polymer solution 10 min before the game and at half-time. Five control team (CT) players ingested equal volumes of placebo at the same times. The players were biopsied in the vastus lateralis before and after the game. The change in muscle glycogen was less (p less than 0.01) in ET (111 +/- 24 mmol glucose units.kg-1 dry muscle) than in CT (181 +/- 24 mmol.kg-1). Blood glucose concentration was not changed after the game in either group. This study demonstrates that glucose ingestion reduces net muscle glycogen utilization in a field setting, i.e. soccer match play.
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Myosin heavy chain isoforms in single fibres from m. vastus lateralis of soccer players: effects of strength-trainingx.
The effects of carbohydrate supplementation on immune responses to a soccer-specific exercise protocolThe aim of this study was to determine the effect of carbohydrate (CHO) versus placebo (PLA) beverage consumption on the immune and plasma cortisol responses to a soccer-specific exercise protocol in 8 university team soccer players. In a randomized, counterbalanced design, the players received carbohydrate or placebo beverages before, during and after two 90min soccer-specific exercise bouts (3 days apart) designed to mimic the activities performed and the distance covered in a typical soccer match. Blood and saliva samples were collected before, during and after the exercise protocol. Plasma lactate concentration increased to ~4 mmol.l-1 at 45 and 90 min of exercise in both treatments (P< 0.01). Plasma glucose concentration was significantly lower after 90 min of exercise with ingestion of the placebo than the carbohydrate (PLA: 4.57 +/- 0.12 mmol.l-1; CHO: 5.49 +/- 0.11 mmol.l-1; P< 0.01). The pattern of change in plasma cortisol, circulating lymphocyte count and saliva immunoglobulin A secretion did not differ between the carbohydrate and placebo trials. Blood neutrophil counts were 14% higher 1 h after the placebo trial than the carbohydrate trial (PLA: 4.8 =/- 0.5 x 10 9 cells.l-1; CHO:4.2 +/- 0.5 x 10 9 cells.l-1; P=0.06),but the treatment had no effect on the degranulation response of blood neutrophils stimulated by bacterial lipopolysaccharide. We conclude that, although previous studies have shown that carbohydrate feeding is effective in attenuating immune responses to prolonged continuous strenuous exercise, the same cannot be said for a soccer-specific intermittent exercise protocol. When overall exercise intensity is moderate,and changes in plasma glucose, cortisol and immune variables are relatively small, it would appear that carbohydrate ingestion has only a minimal influence on the immune response to exercise.
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Testing soccer playersTo cope with the physiological demands of soccer, players must be competent across several fitness components. The use of fitness tests in the laboratory and field assist in examining soccer players' capabilities for performance both at the amateur and elite levels. Laboratory tests provide a useful indication of players' general fitness. Accurate test results can be obtained with the use of a thorough methodology and reliable equipment. Laboratory tests are used sparingly during the season because of the time-consuming nature of the tests. Instead, tests are generally carried out at the start and end of the pre-season period to evaluate the effectiveness of specific training interventions. Field tests provide results that are specific to the sport and are therefore more valid than laboratory tests. The reduced cost, use of minimal equipment and the ease with which tests can be conducted make them more convenient for extensive use throughout the season. Although data from laboratory and field tests provide a good indication of general and soccer-specific fitness, individual test results cannot be used to predict performance in match-play conclusively because of the complex nature of performance in competition. Fitness tests in conjunction with physiological data should be used for monitoring changes in players' fitness and for guiding their training prescription.
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Neuropsychological impairment in soccer athletesBackground. Soccer reportedly places participants at risk for neuropsychological impairment, although it is unknown if the risk is associated primarily with concussion, subconcussive blows from heading the ball, or some combination thereof. Moreover, the extent to which younger versus older athletes are at risk for soccer-related cognitive impairment is unclear. We hypothesized that soccer athletes, especially older ones, would show poorer neuropsychological test performance than comparable swimmers. Methods. Thirty-two soccer (26 college and 6 professional) and 29 swimmers (22 college and 7 masters level), all involved for at least 4 years in their sport at collegiate or national levels, participated. In a 2 X 2 (sport X age category) factorial design, all participants underwent 4 neuropsychological tests with 11 outcome measures assessing motor speed, attention, concentration, reaction time, and conceptual thinking. Results. Soccer athletes performed worse than swimmers on measures of conceptual thinking. The older soccer group in particular performed poorly on measures of conceptual thinking, reaction time, and concentration. Among non-goaltender soccer athletes, estimates of career exposure to brain trauma (based on length of career and level of play) predicted significantly poorer test performance on 6 of 11 measures, even after statistically controlling for age. Conclusions. Results provide additional evidence that participation in soccer may be associated with poorer neuropsychological performance, although the observed pattern of findings does not specifically implicate heading as the cause. Although deficits were most apparent among older soccer players, serial neuropsychological testing for early detection of impairment is recommended for younger players as well.
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Total and regional bone mass in female soccer playersx.
Performance characteristics according to playing position in elite soccer.The paper provides a large-scale study into the motion characteristics of top class soccer players, during match play, according to playing position. Three hundred top-class outfield soccer players were monitored during 20 Spanish Premier League and 10 Champions League games using a computerized match analysis system (Amisco Pro, Nice, France). Total distance covered in five selected categories of intensity, and the mean percentage of playing time spent in each activity were analyzed according to playing position. Midfield players covered a significantly greater total distance (p < 0.0001) than the groups of defenders and forwards did. Analyzing the different work rates showed significant differences (p < 0.5 - 0.0001) between the different playing positions. There were no significant differences between halves in the total distance covered, or in distances covered at submaximal and maximal intensities. However, significantly more distance was covered in the first half compared to the second in medium intensities (11.1 - 19 km/h). The current findings provide a detailed description of the demands placed on elite soccer players, according to their positional role at different work intensities, which may be helpful in the development of individualized training programs.
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Aerobic and anaerobic power characteristics of Saudi elite soccer players.x.
Musculoskeletal profile of male collegiate soccer players.Twenty-five collegiate soccer players were evaluated for lower extremity flexibility and muscle strength at the end of preseason training and before the onset of the collegiate soccer season on two successive seasons. The purpose of the evaluation was to determine whether symmetry was present in their legs and whether deficits in flexibility or strength would affect the susceptibility to hamstring or groin muscle strain injuries. The mean (+/- SE) flexibility of the dominant leg for hip abduction was 41 degrees +/- 1.2 degree; for hip flexion, 76 degrees +/- 1.9 degree; for hip extension, 174 degrees +/- 0.7 degree; and for ankle dorsiflexion, 33 degrees +/- 1.3 degree. The mean (+/- SE) isokinetic torque of the dominant leg (tested at 30 degrees per second) for knee extension was 214 +/- 8 newton meters and for flexion was 128 +/- 4 newton meters, while isometric strength for hip flexion was 315 +/- 8 newtons and for ankle plantar flexion was 1721 +/- 58 newtons. No significant differences were found between the dominant and nondominant legs in flexibility or strength. During this study no hamstring or groin strain injuries occurred. The lack of leg muscle strain injuries appeared to be directly related to the initiation of a controlled warmup and stretching program and underlines the importance of this in injury prevention. Interestingly, more than 50% (13 of 25) of the players were found to have significant deficits in one or more specific muscle groups. Two athletes sustained low back strain injuries and one athlete had a knee sprain injury.(ABSTRACT TRUNCATED AT 250 WORDS)
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Field and laboratory testing in young elite soccer playersx.
Force and power of preferred and non-preferred leg in young soccer players.The purpose of this study was to assess the effects of soccer training on strength and power of leg extensor muscles in preadolescent boys and their possible influence in developing a muscular lateral dominance. Twenty male children (mean age 9.6 yr), ten soccer players and ten untrained subjects, participated in this study. Force and power were measured at five constant cranking velocities on an isokinetic bicycle dinamometer. Each isokinetic load was given after each trial. Force and power outputs were calculated for each limb. Soccer players always showed higher and statistically significant differences (p < 0.05) for force and power values for all considered pedal frequencies. No significant differences were observed for force and power values between preferred and non preferred limb. The results demonstrate the effect of soccer training on the increase of force and power of both legs regardless of lateral dominance.
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Development of muscle strength in relation to training level and testosterone in young male soccer players x.
Body composition and nutritional assessments in soccer.This review summarizes results from studies investigating the physical characteristics, daily energy expenditures, diets, and effects of nutritional supplements to the habitual diets of soccer players. The results show that players fall within a wide range of stature and body weight, and they are classified as mesomorphs. The body fat of male players is about 10% of body weight, whereas the average for females is about 21%. Energy expenditure for males is about 4,000 kcal on training days and 3,800 kcal on match day, while energy intake reported in other studies is on the order of 3,700 kcal. Carbohydrate (CHO), fat, and protein intakes are about 53, 30, and 14% of energy intake, respectively, the remaining being from alcohol intake. There are indications that CHO supplements might be beneficial during soccer performance. However, more research is needed to clarify the importance of branched-chain amino acid and creatine supplementation in soccer.
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Physiological adaptations to soccer specific endurance training in professional youth soccer playersx.
Effects of nutrition on performance in soccer[qoute]The majority of research on nutrition and physical performance centers around continuous endurance exercise. That appropriate food intake can influence endurance performance is widely recognized. Considering that games in general and soccer in particular enjoy an enormous amount of participation, it should come as no surprise that nutritional influences on soccer performance has been studied. The literature shows that soccer is a glycogen-depleting activity and that work volume and rate are influenced by level of muscle glycogen. The dietary habits of soccer players do not appear to contain optimal carbohydrate intake given the varied, and sometimes minimal, amount of time between games. Nutritional assessment and counseling, if necessary, are suggested to afford the player adequate glycogen stores to work at the rate and volume demanded by the game.
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Comparison of the kinematics of the full-instep and pass kicks in soccerx.
Dietary and performance assessment of elite soccer players during a period of intense training.This study examined the nutritional and performance status of elite soccer players during intense training. Eight male players (age 17 +/- 2 years) of the Puerto Rican Olympic Team recorded daily activities and food intake over 12 days. Daily energy expenditure was 3,833 +/- 571 (SD) kcal, and energy intake was 3.952 +/- 1,071 kcal, of which 53.2 +/- 6.2% (8.3 g (.) kg BW(-1)) was from carbohydrates (CHO), 32.4 +/- 4.0% from fat, and 14.4 +/- 2.3% from protein. With the exception of calcium, all micronutrients examined were in accordance with dietary guidelines. Body fat was 7.6 +/- 1.1% of body weight. Time to completion of three runs of the soccer-specific test was 37.65 +/- 0.62 s, and peak torques of the knee flexors and extensors at 60 degrees (.) s(-1) were 139 +/- 6 and 225 +/- 9 N (.) m, respectively. Players' absolute amounts of CHO seemed to be above the minimum recommended intake to maximize glycogen storage, but calcium intakes were below recommended. Their body fat was unremarkable, and they had a comparatively good capacity to endure repeated bouts of intense soccer-specific exercise and to exert force with their knee extensors and flexors.
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Cognitive knowledge and soccer performance.Two experiments examined whether 12 experienced soccer players would exhibit greater task-specific cognitive knowledge than would 12 inexperienced players. Ss viewed structured and unstructured soccer action sequences on a video projection screen. In recalling specific player positions following brief (10-sec) film clips, inexperienced Ss had larger recall of errors than did experienced Ss on structural trials only. This finding indicates that experienced Ss' cognitive knowledge permitted more meaningful associations between players' positions, resulting in more efficient retrieval. When recognition of previously viewed film clips was examined, experienced Ss were more accurate in recognizing structured trials only. Experienced soccer players seem to have a more complex and discriminating organization of long-term memory that facilitates the encoding of task-specific information. (PsycINFO Database Record (c) 2009 APA, all rights reserved)
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Seasonal birth distribution of west European soccer players: a possible explanation.Twice as many top soccer players from The Netherlands, Belgium and France are born in August, as compared to July. A creeping selection mechanism, inadvertently caused by organisational aspects of the youth soccer competition in the countries mentioned, could be the explanation.
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Factors influencing physiological responses to small-sided soccer gamesx.
Pre- and post-season dietary intake, body composition, and performance indices of NCAA division I female soccer players.Little published data describe the dietary and physiological profiles of intercollegiate female soccer players; therefore, the purpose of this investigation was to report baseline dietary data, anthropometrics, and performance indices of soccer women during rigorous pre-season training (2 sessions/day) and then during the post-competitive season. Members of a NCAA Division I women's soccer squad completed 3-day diet records, anthropometrics, and physical tests, including VO2peak. Average body mass was 62 kg with 16% body fat, and no significant pre to post differences were observed. Total energy, carbohydrate (CHO), protein, and fat intakes were significantly greater during the pre-season. Pre-season energy intake met the DRI for females with an "active" lifestyle (37 kcal/kg). While CHO intake failed to meet minimum recommendations to promote glycogen repletion (7-10 g/kg), protein and fat intakes were above minimum recommendations. Pre- and post-season intakes of several micronutrients were marginal (<75% of the DRI) including vitamin E, folate, copper, and magnesium. VO2peak significantly improved from pre- to post-season (42 and 50 ml/kg/min). In this study female soccer players appeared to meet caloric needs during periods of training but failed to meet minimum CHO and micronutrient recommendations. Foods higher in protein and fat displaced more CHO-rich and nutrient-dense foods within athletes' energy requirements and satiety limits.
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Investigation of the effects of the pre-cooling on the physiological responses to soccer-specific intermittent exercise x.
Professional Football (Soccer) Players Have a Markedly Greater Skeletal Mineral Content, Density and Size Than Age- and BMI-Matched Controlsx.
Changes in Exercise Performance and Hormonal Concentrations Over A Big Ten Soccer Season in Starters and NonstartersAs a consequence of the physiological demands experienced during a competitive soccer season, the antagonistic relationship between anabolic and catabolic processes can affect performance. Twenty-five male collegiate soccer players were studied throughout a season (11 weeks) to investigate the effects of long-term training and competition. Subjects were grouped as starters (S; n = 11) and nonstarters (NS; n = 14). Measures of physical performance, body composition, and hormonal concentrations (testosterone [T] and cortisol [C]) were assessed preseason (T1) and 5 times throughout the season (T2-T6). Starters and NS participated in 83.06% and 16.95% of total game time, respectively. Nonstarters had a significant increase ( + 1.6%) in body fat at T6 compared to T1. Isokinetic strength of the knee extensors (1.05 rad-sec-1) significantly decreased in both S (-12%) and NS (-10%; p > 0.05) at T6. Significant decrements in sprint speed ( + 4.3%) and vertical jump (-13.8%) were found at T5 in S only. Though within normal ranges (10.4-41.6 nmol-L-1), concentrations of T at T1 were low for both groups, but increased significantly by T6. Concentrations of C were elevated in both groups, with concentrations at the high end of the normal range (normal range 138-635 nmol-L-1) at T1 and T4 in NS and T4 in S, with both groups remaining elevated at T6. Data indicate that players entering the season with low circulating concentrations of T and elevated levels of C can experience reductions in performance during a season, with performance decrements exacerbated in starters over nonstarters. Soccer players should therefore have a planned program of conditioning that does not result in an acute overtraining phenomenon prior to preseason (e.g., young players trying to get in shape quickly in the 6 to 8 weeks in the summer prior to reporting for preseason camp). The detrimental effects of inappropriate training do not appear to be unloaded during the season and catabolic activities can predominate.
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Biochemical assessments of oxidative stress, erythrocyte membrane fluidity and antioxidant status in professional soccer players and sedentary controlsx.
Validity of simple field tests as indicators of match-related physical performance in top-level professional soccer players.The aim of this study was to examine the construct validity of selected field tests as indicators of match-related physical performance. During the competitive season, eighteen professional soccer players (age 26.2 +/- 4.5 yrs, mass 80.8 +/- 7.8 kg, and height 181.9 +/- 3.7 cm) completed an incremental running field test to exhaustion, a vertical-jump and a repeated-sprint ability (RSA) test. Match physical performance was quantified during official matches using a video-computerized, semi-automatic, match analysis image recognition system, (ProZone, Leeds, UK). The selected measures of match physical performance were: total distance covered (TD), high intensity running (HIR: > 14.4 km . h (-1)), very high intensity running (VHIR:> 19.8 km . h (-1)), sprinting (> 25.2 km . h (-1)) and top running speed. Significant correlations were found between peak speed reached during the incremental field test and TD (r = 0.58, R (2) = 0.34; p < 0.05), HIR (r = 0.65, R (2) = 0.42; p < 0.01) and VHIR (r = 0.64, R (2) = 0.41; p < 0.01). Significant correlations were also found between RSA mean time and VHIR (r = - 0.60, R (2) = 0.36; p < 0.01) and sprinting distance (r = - 0.65, R (2) = 0.42; p < 0.01). Significant differences were found between the best and worst group as defined by the median split technique for peak speed (TD = 12 011 +/- 747 m vs. 10 712 +/- 669, HIR = 3192 +/- 482 m vs. 2314 +/- 347 m, and VHIR = 1014 +/- 120 vs. 779 +/- 122 m, respectively; p < 0.05) and RSA mean time (VHIR = 974 +/- 162 m vs. 819 +/- 144 m, and sprinting = 235 +/- 56 vs. 164 +/- 58 m, respectively; p < 0.05). In conclusion, this study gives empirical support to the construct validity of RSA and incremental running tests as measures of match-related physical performance in top-level professional soccer players.
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Imagery effects on the performance of skilled and novice soccer players.The purpose of this study was to investigate the effect of an imagery training programme on the performance of a soccer task by skilled and novice players. An initial assessment of performance on the soccer task was undertaken, and then 22 skilled and 22 novice players were equally and randomly assigned to either a control or an experimental group. The experimental group was given an imagery training programme consisting of both visual and kinaesthetic imagery, and in which both internal and external imagery perspectives were included. The programme lasted 6 weeks, with the subjects attending bi-weekly sessions of approximately 15 min each. The control group developed a competitive strategy that was totally unrelated to the performance task. Similar to the experimental group, the controls did this over a 6-week period, attending bi-weekly sessions of 15 min duration. Two performance measures were recorded--response time (i.e. the time to complete the soccer task) and performance accuracy (i.e. errors in performing the soccer task recorded in the form of time penalties). Performance on the post-test as measured by response time revealed a significant improvement for both the skilled and novice players in the imagery group. The control group failed to show any such improvement. No effects were found for performance accuracy.
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Changes Evaluated in Soccer-Specific Power Endurance Either With or Without a 10-Week, In-Season, Intermittent, High-Intensity Training ProtocolThe purpose of this study was to evaluate changes in soccerspecific power endurance of 34 female high school soccer players throughout a season either with or without an intermittent, high-intensity exercise protocol. Thirty-four female high school soccer players were tested prior to the 2000 fall season and again 10 weeks later. The tests included an abridged 45-minute shuttle test (LIST), hydrostatic weighing, vertical jump, 20-m running-start sprint, and 30-second Wingate test. The experimental group (EG; n = 17, age 16.5 +/- 0.9 years) completed a 10-week in-season plyometric, resistive training, and high-intensity anaerobic program. The control group (n = 17, age 16.3 +/- 1.4 years) completed only traditional aerobic soccer conditioning. Statistical signifi-cance was set at [alpha] < 0.05. The experimental group showed significant improvements in the LIST (EG = D394 seconds +/- 124 seconds), 20-m sprint (EG = D20.10 seconds +/- 0.10 seconds), increase in fat-free mass (EG = D1.14 kg +/- 1.22 kg), and decreases in fat mass (EG = D21.40 kg +/- 1.47 kg) comparing pre- to postseason. This study indicates that a strength and plyometric program improved power endur-ance and speed over aerobic training only. Soccer-specific power endurance training may improve match performance and decrease fatigue in young female soccer players.
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High femoral bone mineral content and density in male football (soccer) playersx.
Cardiovascular Events during World Cup SoccerMethods Cardiovascular events occurring in patients in the greater Munich area were prospectively assessed by emergency physicians during the World Cup. We compared those events with events that occurred during the control period: May 1 to June 8 and July 10 to July 31, 2006, and May 1 to July 31 in 2003 and 2005.
Results Acute cardiovascular events were assessed in 4279 patients. On days of matches involving the German team, the incidence of cardiac emergencies was 2.66 times that during the control period (95% confidence interval [CI], 2.33 to 3.04; P<0.001); for men, the incidence was 3.26 times that during the control period (95% CI, 2.78 to 3.84; P<0.001), and for women, it was 1.82 times that during the control period (95% CI, 1.44 to 2.31; P<0.001). Among patients with coronary events on days when the German team played, the proportion with known coronary heart disease was 47.0%, as compared with 29.1% of patients with events during the control period. On those days, the highest average incidence of events was observed during the first 2 hours after the beginning of each match. A subanalysis of serious events during that period, as compared with the control period, showed an increase in the incidence of myocardial infarction with ST-segment elevation by a factor of 2.49 (95% CI, 1.47 to 4.23), of myocardial infarction without ST-segment elevation or unstable angina by a factor of 2.61 (95% CI, 2.22 to 3.08), and of cardiac arrhythmia causing major symptoms by a factor of 3.07 (95% CI, 2.32 to 4.06) (P<0.001 for all comparisons).
Conclusions Viewing a stressful soccer match more than doubles the risk of an acute cardiovascular event. In view of this excess risk, particularly in men with known coronary heart disease, preventive measures are urgently needed.
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Fluid and electrolyte intake and loss in elite soccer players during training.This study measured fluid balance during a 90-min preseason training session in the first team squad (24 players) of an English Premier League football team. Sweat loss was assessed from changes in body mass after correction for ingested fluids and urine passed. Sweat composition was measured by collection from patches attached to the skin at 4 sites. The weather was warm (24-29 degrees C), with moderate humidity (46-64%). The mean +/- SD body mass loss over the training session was 1.10+/- 0.43 kg, equivalent to a level of dehydration of 1.37 +/- 0.54% of the pre-training body mass. Mean fluid intake was 971 +/- 303 ml. Estimated total mean sweat loss was 2033 +/- 413 ml. Mean sweat electrolyte concentrations (mmol/L) were: sodium, 49 +/- 12; potassium, 6.0 +/- 1.3; chloride, 43 +/- 10. Total sweat sodium loss of 99+/- 24 mmol corresponds to a salt (sodium chloride) loss of 5.8 +/- 1.4 g. Mean urine osmolality measured on pre-training samples provided by the players was 666 +/- 311 mosmol/kg (n = 21). These data indicate that sweat losses of water and solute in football players in training can be substantial but vary greatly between players even with the same exercise and environmental conditions. Voluntary fluid intake also shows wide inter-individual variability and is generally insufficient to match fluid losses.
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Left-right asymmetry in two types of soccer kick. x.
The Sweating Response of Elite Professional Soccer Players to Training in the Heat x.
Isokinetic torques and kicking maximal ball velocity in young soccer players.The purpose of this study is to assess if there is any correlation between isokinetic testing and field performance of young soccer players. The isokinetic peak torques of the knee extensor muscles in sitting position (TKE), and those of the hip flexor muscles in standing position (THF) were measured in 24 junior soccer players. Four angular velocities (omega = 1.05, 3.14, 4.19, 5.23 rad.s-1 or 60, 180, 240, 300 deg.s-1) were used for the knee extensors and three (1.05, 3.14, 4.19 rad.s-1) for the hip flexors. On the field the subjects were asked to kick a stationary soccer ball as fast as possible against a barrier and the mean linear velocity over a 10 m path (v) was measured. TKE of the non dominant limb were higher than those of the opposite one at the three highest omega (p < 0.05). On the contrary the THF of the dominant limbs were higher than those of the controlateral, at the two highest omega. When the ball was kicked by the dominant or non dominant limbs, the mean values and standard deviations (+/- SD) of v were 23.6 (+/- 2.5) and 21.4 (+/- 2.6) m.s-1. Torques and v were always positively correlated to each other; however, only in few cases was this relationship statistically significant. In conclusion the isokinetic torques do not seem to be good predictors of v, one of the several factors which determine the global performances of the soccer players.
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Energy and macronutrient intakes of professional football (soccer) players.OBJECTIVE: To examine the dietary habits of professional soccer players at two Scottish Premier League clubs during the competitive season. METHODS: A study of the dietary intake of 51 professional soccer players with two different clubs was carried out by the seven day weighed intake method. RESULTS: Physical characteristics of the two groups of players were similar, with only small differences in age and body mass but no difference in height and body fat. Mean (SD) daily energy intake for club A was 11.0 (2.6) MJ, and for club B 12.8 (2.2) MJ. The higher energy intake at club B was largely accounted for by a higher (P < 0.005) fat intake (118 v 93 g d-1): there was no difference in the absolute amounts of protein, carbohydrate, or alcohol consumed. When expressed as a fraction of total energy intake, mean protein intake was higher (P < 0.05) and fat intake lower (P < 0.01) at club A. CONCLUSIONS: The mean energy intake of these players was not high compared with athletes in endurance sports. Fractional contribution of the macronutrients to total energy intake was broadly similar to that of the general population.
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Relationships between field fitness test and basal serum testosterone and Cortisol levels in soccer playersSummary. The aim of this study was to investigate the existence of a relationship between performance capacities and blood levels of testosterone (T) and Cortisol (C). Thirty-two professional soccer players volunteered for the study. Morning levels of hormones were plotted against results of maximal vertical jump with a preparatory counter-movement (CMJ), 30 m running, and Cooper's 12-min running test. The serum T was positively related to both CMJ and average running speed (r= 0.43 and r= 0.47, respectively). Serum levels of C and T were in negative correlation (r= -0.40 and r= -0.49, respectively) with the results of Cooper's test. It was concluded that athletes with better explosive strength and sprint running performances have a higher basal level of testosterone. The results suggest a relationship between testosterone production and development of fast twitch muscle fibres in athletes.
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Physiological profiles of the Canadian Olympic Soccer Team.Physiological profiles of elite athletes are becoming increasingly important both for the sport scientist and coach, primarily to effectively develop training programs and to use as a motivational tool in the pursuit of excellence. Descriptive profiles were developed on 16 aspirants of the Canadian Olympic Soccer team during their training program at U.B.C. Selected strength measures were obtained from a Cybex II isokinetic dynamometer at 30 degrees sec-1. Metabolic variables were derived utilizing a Beckman metabolic cart interfaced with a Hewlitt Packard 3052A data acquisition system. Protocols involved were the following: VO2max (initial velocity 8.05 km X h-1, greater than 0.805 km X min-1); Anaerobic speed test (AST) (20% grade, 12.8 km X h-1). the nonlinear increase in excess CO2 was utilized to determine the anaerobic threshold (AT). (Table: see text). Recommendations emphasized maintenance of low body fat, increasing maximal aerobic power by approximately 10% and creating a hams/quads ratio of 60%. Also, a nutritional survey and periodic evaluation of iron status is necessary for the athletes.
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Carbohydrate and fluid needs of the soccer player.Soccer is a game that demands a combination of repeated maximal sprinting wit with 10 to 11km of moderate running, sometimes performed under extremely warm conditions. Over the course of a match, there is partial to near complete depletion of glycogen reserves in the leg muscles (depending on the extent of initial reserves and the level of competition), with a resultant decrease in physical performance. Blood glucose levels also fall, sometimes to values likely to cause a deterioration of both tactical thinking and cooperation between players (3.0 to 3.8 mmol/L), while in tropical climates, fluid losses can amount to 4 to 5kg of bodyweight. The effectiveness of glucose solutions in correcting these problems is limited for 2 main reasons: concentrations greater than 2.5% slow the rate of gastric emptying and thus fluid absorption, while provoking a secretion of insulin with a resultant hypoglycaemia. Fructose solutions are less liable to increase insulin secretion, but they have an equal propensity for slowing gastric emptying; moreover, the ingested fructose is largely metabolised in the liver, without boosting blood glucose. However, glucose polymer preparations have a low osmotic pressure per unit content of glucose equivalent, so that substantial amounts of carbohydrate can be administered in this fashion before gastric emptying is inhibited. If polymers are given before and during a soccer game, they sustain blood glucose, sparing muscle glycogen stores and increasing game performance. If the concentration of polymer is too high, one possible complication is a movement of water from the plasma into the gut; nevertheless, with an appropriate choice of concentration (for example, 7% polycose, 360 mOsm/L, plasma volume is increased rather than decreased relative to that seen with administration of water. Probably because the intergame interval for competitive soccer players is short, replenishment of glycogen reserves proceeds quite slowly. Moreover, this process does not seem to be helped by ingestion of either glucose polymers or a high carbohydrate diet.
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The Effect of A Combined High-Intensity Strength and Speed Training Program on the Running and Jumping Ability of Soccer PlayersThe purpose of this study was to investigate the effect of a combined heavy-resistance and running-speed training program performed in the same training session on strength, running velocity (RV), and vertical-jump performance (VJ) of soccer players. Thirty-five individuals were divided into 3 groups. The first group (n = 12, COM group) performed a combined resistance and speed training program at the same training session, and the second one (n = 11, STR group) performed the same resistance training without speed training. The third group was the control group (n = 12, CON group). Three jump tests were used for the evaluation of vertical jump performance: squat jump, countermovement jump, and drop jump. The 30-m dash and 1 repetition maximum (1RM) tests were used for running speed and strength evaluation, respectively. After training, both experimental groups significantly improved their 1RM of all tested exercises. Furthermore, the COM group performed significantly better than the STR and the CON groups in the 30-m dash, squat jump, and countermovement jump. It is concluded that the combined resistance and running-speed program provides better results than the conventional resistance training, regarding the power performance of soccer players.
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Muscle Strength and Flexibility in Different Positions of Soccer Players One-hundred eighty soccer players were tested for muscle strength in knee extension and knee flexion and for flexibility in the lower extremity. The strength measurements were done with a Cybex II isokinetic device (Lumex, Bay Shore, New York). The range of motion (ROM) was measured according to a method described by Ekstrand et al. (1982). The players were divided into groups according to their player position: goalkeepers, defenders, midfielders, and forwards.
The results showed a significantly higher knee extensor torque in goalkeepers and defenders than in forwards (P < 0.05). The knee flexion/knee extension ratio (H/Q ratio) was significantly higher for forwards compared to goalkeepers (P < 0.001) and defenders (P < 0.01). The goalkeepers were significantly more flexible than the other players in hip flexion (P < 0.001), knee flexion (P < 0.01), and ankle dorsiflexion (P < 0.001).
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The effect of carbohydrate ingestion on the motor skill proficiency of soccer players.This study examined the effects of ingesting a glucose-polymer (GP) solution on the motor skill proficiencies of association football (soccer) players from two teams playing during two matches in a cool environment. Fifteen minutes before each match and at halftime, players from both teams ingested 5 ml/kg of either placebo or a 6.9% GP solution. GP ingestion did not improve tackling, heading, dribbling, or shooting ability. On the contrary, the mean of successful tackles was lower with GP ingestion than with placebo. The success rate for heading, dribbling, and shooting also tended to be lower in the GP than in the placebo condition. In contrast, success in passing and ball control was similar in the two conditions. Improvements in passing and ball control may have been related to a decrease in the intensity of play in the second half of the game. These data indicate that there are no measurable benefits of GP ingestion for the motor skill proficiencies of soccer players during games played in a cool environment.
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Physiological Profile and Activity Pattern of Young Soccer Players during Match Playx.
Specific muscular development in under-18 soccer players.A comparison of the under-18 (U-18) and under-16 (U-16) squads of the Canadian national soccer team with a representative sample of Canadians (Canada Fitness Survey, 1983) showed a tendency for the development or selection of the older players in teams of stature (U-18, 175.8 cm; U-16, 171.1 cm; CFS, 170.9 cm) and lean body mass (U-18, 63.4; U-16, 57.9; CFS, 54.2 kg). The larger lean mass of the older players could not be explained simply by size. The U-18s also showed greater isokinetic leg extension force (particularly for rapid movements) and explosive strength (vertical jump) relative to the younger players, although the knee extension force was less than in some classes of athlete. Part of the gain in mass seems due to local training of the hip and leg muscles and part to a more general muscular development. Contrary to some reports, the hip flexibility of the Canadian players (sit and reach test) was greater than for a national sample; this may be important in avoiding soft tissue injuries to the legs. However, aerobic power (58.3 +/- 5.3 ml kg-1 min-1) and body fat (8.0 +/- 1.1%) were unremarkable.
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Intercollegiate soccer: Saliva cortisol and testosterone are elevated during competition, and testosterone is related to status and social connectedness with teammatesx.
Nutritional guidance to soccer players for training and competition.Strategies for a nutrition education as applied to individual soccer players provide a key to guiding them towards appropriate food selection. Scientific investigations have associated energy requirements, composition of the diet and carbohydrate intake with muscle glycogen storage, and adequacy of fluids with optimal athletic performance. In general, soccer players appear to consume adequate energy but low carbohydrate diets. The training diet should be comprised of 55-65% carbohydrate, 12-15% protein and less than 30% fat. The goal of the training diet is to provide adequate energy for weight maintenance, and 7-10 g of carbohydrate per kg body weight for maximizing glycogen storage. Nutritional needs for competition include eating prior to and after matches. Consumption of carbohydrate-rich foods for energy needs and glycogen resynthesis are key behaviours soccer players need to focus on daily. Qualified dietitians should be on hand to provide personal nutrition counselling, carbohydrate resource lists and education on food labels as simple and quick nutrition education strategies to guide soccer players, their parents, coaches and trainers towards improved food selections.
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Playing soccer increases serum concentrations of the biochemical markers of brain damage S-100B and neuron-specific enolase in elite players: a pilot studyx.
Plasma oxidative stress biomarkers, nitric oxide and heat shock protein 70 in trained elite soccer playersThe physiological response to the physical exercise involves a number of changes in the oxidative balance and in the metabolism of some important biological molecules, including nitric oxide (NO) and heat shock proteins (Hsp 70). With the aim to optimise previous laboratory diagnostic panels, we measured the plasma concentration of reactive oxygen metabolites (ROMs), total antioxidant status (TAS), glutathione reductase (GR) activity, and NO and Hsp 70 levels in 44 elite, antioxidant-supplemented and trained soccer players and in 15 sedentary controls. Although no statistically significant difference between athletes and controls was detected in the plasma level of ROMs and TAS, soccer players showed a significantly higher plasma GR activity, NO and Hst 70 levels than those of sedentary controls. These findings suggest that the measuring of relatively novel biomarkers in sport medicine, like GR, NO and Hsp 70, in addition to the well-known and reliable assays (d-ROMs test and TAS) may be useful to a clinician to better assess and evaluate the benefits of training and/or supplementation programs.
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Skeletal muscle fiber type, fiber size, and capillary supply in elite soccer players.This study determined the fiber type composition, the fiber size, and the capillary characteristics of the vastus lateralis muscle in 11 young, elite, male soccer players and 8 sedentary male, age-matched controls. There were no significant differences (P less than 0.05) in the fiber type percentages and fiber diameter between the soccer players and controls; however, all fiber types tended to be larger in the soccer players. The soccer players possessed a greater capillary supply; this was characterized by a significantly greater mean number of capillaries surrounding each fiber (5.7 +/- 0.9 vs. 4.9 +/- 0.4), a significantly larger capillary density (282.7 +/- 42.0 vs. 220.8 +/- 38.1), and a significantly higher capillary to fiber ratio (2.2 +/- 0.6 vs 1.7 +/- 0.1). The results indicate that soccer may be an appropriate stimulus for simultaneous adaptation to endurance and high intensity exercise.
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The Yo-Yo IR2 Test: Physiological Response, Reliability, and Application to Elite Soccerx.
The Effect of in-Season,High-Intensity Interval Training in Soccer PlayersThe effects of in-season, high-intensity interval training on professional male soccer players' running performances were investigated. Twenty-two subjects participated in 2 consecutive training periods of 10 weeks. The first period was considered a control period and was compared with a period where 2 high-intensity interval training exercises were included in the usual training program. Intermittent runs consisted of 12-15 runs lasting 15 seconds at 120% of maximal aerobic speed alternated with 15 seconds of rest. Sprint repetitions consisted of 12-15 all-out 40-m runs alternated with 30 seconds of rest. Results from the high-intensity interval training have shown that maximal aerobic speed was improved (18.1 +/- 3.1%; p < 0.001) and that the time of the 40-m sprint was decreased (23.5 +/- 1.5%; p < 0.001), whereas no change in either parameters were observed during the control period. This study shows that improvements in physical qualities can be made during the in-season period.
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Carbohydrate intake and multiple sprint sports : With special reference to football (soccer) x.
Stretching Exercise and Soccer: Effect of Stretching on Range of Motion in the Lower Extremity in Connection with Soccer Training Forty-eight players from four senior, male soccer teams were tested for ranges of motion (ROM) in the lower extremity before, immediately after, and 24 h after different forms of soccer training.
The players were tested after regular soccer training (A), after soccer training wih contract-relax stretching prior to beginning the session (B), and after soccer training with stretching added at the end of the program (C). Each training session lasted 1.5 h.
In group A all six ROMs were decreased 24 h after the training. In group B the only change in ROM noted was an increase in knee flexion directly after the training. In group C there was an increase in hip extension, hip flexion, and knee flexion directly after the training.
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Characteristic Plantar Pressure Distribution Patterns During Soccer-Specific Movementsx.
Relation Between Fitness Tests and Match Performance in Elite Italian Soccer RefereesThis study examined the relation between field-test results and match performance in elite Italian soccer referees. Subjects (n = 22) were all experienced elite-level referees enrolled in the Commissione Arbitri Nazionali (CAN) and thus officiating in the Serie A and B Italian championships. Referees were, on separate occasions, tested for fitness (50-m, 200-m, and 12-minute run tests) and observed a minimum of 1 and a maximum of 3 times (n = 39) during Serie A matches. Match analyses were performed considering 11 match activity categories. Analyses of correlations were performed considering 50-m, 200-m, and 12-minute run test performances as independent variables and total distance, maximal speed distance (runs performed at speeds faster than 24 km[middle dot]h-1), and high-intensity activity distance (runs performed at speeds faster than 18 km[middle dot]h-1, high intensity activity [HIA]) as dependent variables. Statistical significance was set at p <= 0.05. In the 50-m, 200-m, and 12-minute run tests the referees scored, 7.07 +/- 0.26 seconds, 29.57 +/- 1.44 seconds, and 2866 +/- 164 m, respectively. The 12-minute run test showed a moderate correlation with total match distance (r = 0.71, p < 0.05), and a low correlation with HIA and maximal speed distance (r = 0.51, p < 0.05 and r = 0.32, p < 0.05, respectively). The 200-m and 50-m sprint times were not correlated with the distance covered at maximal speed or HIA, but correlated negatively with match distance (r = -0.48, p < 0.05 and r = -0.38, p < 0.05, respectively). The results of the present study demonstrate that the 12-minute run test is a moderate predictor of match performance in elite referees and that aerobic fitness should have priority in the physical conditioning programs of the elite soccer referee.
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Effect of adding cognitively demanding tasks on soccer skill performance.The effect of adding cognitively demanding elements to the performance of a real-world motor task in which functional interference existed among the elements in performance was investigated across level of expertise. The primary task involved running as quickly as possible through a slalom course. Two secondary tasks were used: running through the slalom while dribbling a soccer ball and identification of geometric shapes projected on a screen at the end of the slalom course. Four novice, 5 intermediate, and 5 expert female soccer players performed 3 trials each of the 3 experimental conditions. Although the addition of cognitively demanding elements caused a decrement in performance, the amount of decrement decreased as level of expertise increased. (PsycINFO Database Record (c) 2009 APA, all rights reserved)
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Ego-involvement and task-involvement: Related conceptions of ability, effort, and learning strategies among soccer players.Conducted 2 experiments to verify that the conceptions presented by professional soccer players or varsity soccer players are dependent on their ego vs task involvement conditions (Exp 1) or their motivational ego vs task orientations (Exp 2). Since a strong interaction was obtained between motivational goals and competence feedback on related effort assumptions, the study predictions received empirical support. Furthermore, because previous research in academic settings also indicated that individual differences in goal orientations are positively related to the kind of information strategies used, a 2nd set of predictions concerned the determinants of learning strategies in sport context (i.e., soccer shooting). Results confirmed previous findings showing that, in comparison to ego-orientated Ss, task-oriented Ss use more deep-processing strategies irrespective of the kind of feedback provided. (French, Spanish, German & Italian abstracts) (PsycINFO Database Record (c) 2009 APA, all rights reserved)
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Effective conditioning of female soccer players.We compared the efficacy of three physical conditioning programmes provided over a 12 week period (24 h in total) on selected anthropometric and physical fitness parameters in female soccer players. Two of the groups received physical conditioning training in accordance with speed, agility and quickness (SAQ); one group used specialized resistance and speed development SAQ equipment (equipment group; n = 12), while the other group used traditional soccer coaching equipment (non-equipment group; n = 12). A third group received their regular fitness sessions (active control group; n = 12). All three interventions decreased (P < 0.001) the participants' body mass index (-3.7%) and fat percentage (-1.7%), and increased their flexibility (+14.7%) and maximal aerobic capacity (VO2max) (+18.4%). The participants in the equipment and non-equipment conditioning groups showed significantly (P < 0.005) greater benefits from their training programme than those in the active control group by performing significantly better on the sprint to fatigue (-11.6% for both the equipment and non-equipment groups versus -6.2% for the active control group), 25 m sprint (-4.4% vs -0.7%), left (-4.5% vs -1.0%) and right (-4.0% vs -1.4%) side agility, and vertical (+18.5% vs +4.8%) and horizontal (+7.7% vs +1.6%) power tests. Some of these differences in improvements in physical fitness between the equipment and non-equipment conditioning groups on the one hand and the active control group on the other hand were probably due to the specificity of the training programmes. It was concluded that SAQ training principles appear to be effective in the physical conditioning of female soccer players. Moreover, these principles can be implemented during whole team training sessions without the need for specialized SAQ equipment. Finally, more research is required to establish the relationship between physical fitness and soccer performance as well as the principles underlying the improvements seen through the implementation of SAQ training programmes.
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THE BIOMECHANICS OF KICKING IN SOCCEROf all the skills required to participate in soccer, none has received more attention from a biomechanical perspective than kicking. When skilled behavior, such as kicking, is evaluated there are two successive stages. Initially, movements are organized and simplified through powerful, temporal coupling between joint complexes so that the neuromuscular system becomes functionally useful for the learner. In the second stage, the learner's behavior becomes more efficient and organized as the active muscular and joint forces become more economical. [10]
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Performance affect in soccer players: an application of the IZOF model.Individual patterns of positive-negative affect (PNA) were studied in 25 Olympic level soccer players (age 17-21). Recall idiographic scaling following the methodology of the individual Zones of Optimal Functioning (IZOF) model was used to identify PNA items related to each player's effective and ineffective game performance. Individual zones for each item were then estimated on the Borg's Category Ratio (CR-10) scale. Optimal and non-optimal PNA patterns were revealed in the selection of idiosyncratic items, their intensity ranges and functions. All PNA items were functionally either facilitating (23.1%), debilitating (42.3%), or both (34.6%). Significant differences in PNA content and intensity (zones) were revealed only at intra- and inter-individual but not at the group level. Pre-game negative ineffective affect in successful players anticipated two days before the important tournament deviated more from non-optimal zones than in less successful players. The data support the findings obtained in ice-hockey and extend Hanin's IZOF model to performance PNA in soccer. Implications for idiographic assessments and application of the IZOF model in team sports are suggested.
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Omega-3 fatty acid supplementation does not improve maximal aerobic power, anaerobic threshold and running performance in well-trained soccer playersx.
10-year trend in USA Cup soccer injuries: 1988-1997Objective: To prospectively document the incidence of competition-related injury rates in an international youth soccer tournament and to analyze the type and location of injuries by age and gender.
Design: A prospective injury report form completed for injured players presenting to a medical facility for evaluation by the medical staff.
Setting: An international youth soccer tournament occurring annually during mid-July.
Participants: 89,500 soccer players, ages 9-19.
Measurement/Main Results: A total of 3840 new, play-related injuries were evaluated during 290,344 player-hours of competition from 1988 through 1997. New, play-related injuries per 1000-player-hours decreased from 19.87 in 1988 to 9.89 in 1997. Female injury rates ranged from a maximum of 20.11 in 1989 to a minimum of 10.23 in 1996 and the male injury rate ranged from a maximum of 20.04 in 1988 to a minimum of 7.60 in 1996. The lowest injury rate occurred in the under-19 females (10.64) and highest rates occurred in under-16 (17.68) and under-15 (16.92) females. Heat illness correlated with mean temperature. The aggregate rate of heat illness was 0.6 cases/1000 player-hours under normal conditions compared to a rate of 2.8/1000 player-hours during hot years.
Conclusions: Injury rates for both genders declined over the 10-yr span of the USA Cup study. The aggregate rate of injury was slightly higher for females than males although the difference between male and female rates became less significant as the tournament matured. In conditions of extreme heat and humidity (1988 and 1995) the rate of new, heat illness increased compared with normal years and females were 1.6 times more likely to sustain heat illness than males.
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Endogenous Nandrolone Metabolites in Human Urine. Two-Year Monitoring of Male Professional Soccer Players19-Norandrosterone (19-NA) and 19-noretiocholanolone (19-NE) are the two main indicators used to prove the illegal use of nandrolone by humans. Recent studies showed that 19-NA and 19-NE can be endogenously produced in some individuals. The mediated cases observed over the last three years generated some questions about the appropriateness of the official International Olympic Committee cutoff level, which is 2 ng/mL of 19-NA in male urine samples. In the present study, professional soccer players belonging to the French First League were studied over a period of 19 months. In total, 385 urine samples were taken immediately before and after soccer competitions and were coupled with 200 blood samples for testosterone and LH determination. Results of the study showed that the mean values for 19-NA and 19-NE were 0.097 ng/mL and 0.033 ng/mL, respectively. For 19-NA, 70% of the samples proved to be below 0.1 ng/mL, whereas less than 20% were found to be between 0.1 and 0.2 ng/mL, and 7% were between 0.2 and 0.3 ng/mL. Only four urine samples were above 1.0 ng/mL; the maximal value was 1.79 ng/mL. For 19-NE, only one sample was above 1.0 ng/mL; the value was 1.42 ng/mL. Concentrations of these compounds after games were generally significantly higher than those before games.
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Effects of combined strength and kick coordination training on soccer kick biomechanics in amateur playersx.
Physiological, psychological and performance measures during an endurance record for five-a-side soccerx.
Fitness assessment of English league soccer players through the competitive season.A battery of 26 tests was administered to professional soccer players (n = 31) at 3 points during the competitive season. Significant changes from start to mid-season were limited to improved muscular power, increased resting heart rate (fH), decreased force expiratory flow (FEF) and ankle mobility. No further changes with the duration of the competitive season were observed. Differences between squads were predominantly cardiac function measures at mid-season, and strength, muscular power and limb girths at the end of the season. The First Team squad had consistently less fat and poorer ankle mobility. It seems that mean fitness levels remain relatively stable during the playing season, though the measures significantly discriminating between the top and reserve squads fluctuate.
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Isokinetic maximal torque power of greek elite soccer players.Eighteen elite Greek soccer players (age, 27.8 +/- 3.4 years; height, 176.6 +/- 5.2 cm; weight, 75.5 +/- 5.2 kg) were tested on the Cybex(R) II apparatus in order to determine 1) the maximal muscle power for the lower extremity dominant side at angular velocities of 30 degrees /sec, 90 degrees /sec, and 180 degrees /sec; 2) the total muscular output and the relative power at 30 degrees /sec; 3) the relationship between the muscle power of the agonist and antagonist musculature. The absolute maximal muscle power (Nm) at 30 degrees /sec for the different joint movements was as follows: Hip Ext = 269 +/- 39; Hip Flex = 179 +/- 29; Hip Add = 160 +/- 17; Hip Abd = 119 +/- 24; Knee Ext = 247 +/- 29; Knee Flex = 146 +/- 12; PI. Flex = 120 +/- 22; and Do. Flex = 32 +/- 6. The muscle agonist-antagonist percent relationship at 30 degrees /sec was found to be: (hip flex)/(hip ext) = 66%(hip abd)/(hip add) = 74%(knee flex)/(knee ext) = 60%(dor. fle)/(pl. fle) = 28%These findings have significant implications for preseason conditioning programs as well as for minimizing the rate of muscle injuries by restoring the correct relationship between agonist-antagonist musculature.J Orthop Sports Phys Ther 1985;6(5):293-295.
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Measurement of total energy expenditure by the doubly labelled water method in professional soccer playersx.
Suitability of Soccer Training Drills for Endurance TrainingRecent evidence suggests that certain soccer drills produce exercise intensities suitable for physical conditioning. However, it remains debatable whether soccer drills can provide a sufficiently unified exercise intensity among different players and on repetition of a drill, because movement patterns cannot be externally controlled during soccer drills. Good reliability and low variability of exercise intensity would enable all players to receive an appropriate training stimulus. The purpose of this study was to investigate intersubject variability and intrasubject reliability in exercise intensity during soccer drills. It was hypothesized that soccer drills that involve the highest exercise intensities would demonstrate the lowest intersubject variability and the highest intrasubject reliability. Heart rates of 23 professional soccer players were recorded during a range of soccer training drills. The drills consisted of 2 vs. 2 to 8 vs. 8 normal scoring games and 2 further possession games. Heart rate responses were examined for variability, reliability, and suitability for soccer endurance training. Coefficients of variation across players were less than 3% for all drills. Paired t-tests showed no significant differences in heart rate on repetition of the drills and 95% ratio limits of agreement were 1.8-3.8%. There were no significant correlations between exercise intensity and the statistical measures of variability and reliability. Several drills produced exercise intensities suitable for soccer endurance training with mean heart rate responses ranging from 87-91% HRmax. Soccer drills such as those used in the present study appear to be an adequate substitute for physical training without the ball and thus provide simultaneous skill and fitness training. The increase in training time spent developing technical ability and/or a reduction in total training time required may be useful for soccer teams.
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Validity of heart rate as an indicator of aerobic demand during soccer activities in amateur soccer playersx.
Bilateral isokinetic peak torque of quadriceps and hamstring muscles in professional soccer players with dominance on
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The Influence of In-Season Injury Prevention Training on Lower-Extremity Kinematics during Landing in Female Soccer Playersx.
Carbohydrate, fluid, and electrolyte requirements of the soccer player: a review.Soccer requires field players to exercise repetitively at high intensities for the duration of game, which can result in marked muscle glycogen depletion and hypoglycemia. A soccer match places heavy demands on endogenous muscle and liver glycogen stores and fluid reserves, which must be rapidly replenished when players complete several matches within a brief period of time. Low concentrations of muscle glycogen have been reported in soccer players before a game, and daily carbohydrate (CHO) intakes are often insufficient to replenish muscle glycogen stores. CHO supplementation during soccer matches has been found to result in muscle glycogen sparing (39%), greater second-half running distances, and more goals being scored with less conceded, when compared to consumption of water. Thus, CHO supplementation has been recommended prior to, during, and after matches. In contrast, there is currently insufficient evidence to recommend without reservation the addition of electrolytes to a beverage for ingestion by players during a game resulting in sweat losses of < 4% of body weight.
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Thermoregulatory observations in soccer match play: professional and recreational level applications using an intestinal pill system to measure core temperaturex.
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Skill, Strategy, and Passion: an Empirical Analysis of Soccer#Sports provide a natural experiment on individual choices in games with high stakes.
We study soccer with a gameMtheoretic model of a match, and then evaluate the ability
of this model to explain actual behavior with data from 2885 matches among professional
teams. In our model, the strategy of a team depends on the current state of the game.
When the game is tied, both teams attack. A losing team always attacks, while its winning
opponent attacks early in the game, but it starts defending as the end of the match nears.
We find that teamsG skills, current score, and home field advantage are significant exM
planatory variables of the probability of scoring. We also find that a team which falls
behind is relatively more likely to score. A team which is ahead, on the other hand, uses a
conservative strategy very early in the match.
These results support the main conclusions of our model. They indicate that soccer
teams behave consistently with rationality and equilibrium. However, there is significant
evidence that emotional factors are roughly as important as rational ones in determining
the gameGs outcome, and they affect the strategic decisions of teams.
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Sports-specific adaptation of left ventricular muscle mass in athlete's heart. II: An echocardiographic study with 400-m runners and soccer players.Regarding the influence of the left ventricular (LV) adaptation by sports-specific factors the supposed endurance training have so far been compared mainly to strength conditioning. In the present study we investigated the echocardiographic LV measurements of endurance-trained athletes in different kinds of endurance sports (running and ball games) by using matched-pair procedures. We examined 22 male soccer players (S) and 22 male 400-m runners (R) on a regional up to a national level with--each similar in pairs--the following body mass (S: 75.7 +/-5.0 kg; R: 75.2 +/- 5.6), body surface area (S: 1.97 +/- 0.09 m2; R: 1.98 +/- 0.09), fat-free body mass (S: 68.4 +/- 4.6 kg; R: 68.3 +/- 5.3) and individual anaerobic threshold as a criterion to determine the running endurance (S: 14.23 +/- 0.79 km.h-1; R: 14.25 +/- 0.80). The body dimensions-related heart volume (HV/lean body mass: S: 14.2 +/- 1.5 ml.kg-1; R: 13.4 +/- 1.0) as well as the absolute and body surface-related LV internal diameter (EDD: S: 55.0 +/- 3.8 mm; R: 52.7 +/- 3.3; EDD/body-surface area: S: 27.8 +/- 1.9 mm.m-2; R: 26.6 +/- 1.3) were measured significantly higher in S as compared to R (p < 0.05 and p < 0.01, respectively). In both groups, free LV wall thickness, enddiastolic diameter and LV muscle mass correlated significantly with the body dimensions (fat-free body mass: r = 0.42 - 0.48 - 0.56; p < 0.004, respectively). In conclusion, specific sport-related strain like frequent exercises in interval form (typical for ball games) and a different volume/intensity ratio could significantly influence the LV adaptation beside the endurance performance as well as constitutional and genetic factors.
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Body Composition of Professional Football (Soccer) Players Determined by Dual X-Ray Absorptiometryx.
Epidemiology of 1.6 Million Pediatric Soccer-Related Injuries Presenting to US Emergency Departments From 1990 to 2003x.
Aerobic Fitness and Yo-Yo Continuous and Intermittent Tests Performances in Soccer Players: Acorrelation StudyYoyo tests are very popular in soccer; however, no study has addressed details of their relation to canonical aspects of aerobic fitness. Furthermore, no information is available on the effect of the individual levels of lower limbs' explosive strength on yo-yo tests in soccer players. The purpose of this study was to examine the physiological determinants of Yo-yo Endurance Test Level 2 (YYETL2) and Yo-yo Intermittent Recovery Test Level 1 (YYIRTL1) in soccer players. Twenty-four soccer players (body mass, 74.6 +/- 8.5 kg; height, 178.1 +/- 4.5 cm; age, 25.6 +/- 5.1 years) were tested for [latin capital V with dot above]O2max and ventilatory threshold (VT) on a motorized treadmill. Lower-limb explosive strength was assessed using vertical countermovement jumps (CMJ) performed on a force platform. Results showed that YYETL2 and YYIRTL1 performances (m) were significantly related (r = 0.75, p = 0.00002). YYETL2 results were significantly related to [latin capital V with dot above]O2max, [latin capital V with dot above]O2, and speed at VT (r = 0.75, 0.76, and 0.83, respectively; p < 0.00002). Peak treadmill speed results were significantly related to YYETL2 and YYIRTL1 (r = 0.87 and 0.71, respectively; p < 0.0003). YYIRTL1 was related to CMJ peak power (r = 0.57; p = 0.003). These findings show that YYETL2 and YYIRTL1, although adopting similar starting and progression speeds, are influenced by different physiological variables. From these results, YYETL2 can be considered an aerobic fitness-related field test, whereas YYIRTL1 can be regarded as an aerobic-anaerobic, soccer-specific field test.
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EMG activity of the iliopsoas muscle and leg kinetics during the soccer place kickActa Physiologica Scandinavica
Volume 180 Issue 2, Pages 143 - 155
Published Online: 23 Jan 2004
2005 Scandinavian Physiological Society
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Immune system alteration in response to two consecutive soccer gamesx.
Central and peripheral visual reaction time of soccer players and nonathletes.Visual Reaction Time (RT) was measured by presenting three different sizes of stimulus to the central and peripheral fields of vision in 6 soccer players and 6 nonathletes. An electromyogram was recorded from the flexor digitorum superficialis muscle of the responding forearm. Peripheral visual RT was longer in comparison to central visual RT due to an increment in Premotor Time. The soccer players showed shorter Premotor Times during central and peripheral visual RT tasks than nonathletes, suggesting that the soccer players are better able to respond quickly to a stimulus presented to peripheral as well as central positions.
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Gastric emptying of a carbohydrate-electrolyte drink during a soccer matchx.
Physiological training effects of playing youth soccerThe purpose of this investigation was to determine if a 9-wk youth soccer program had any effect on cardiorespiratory fitness (VO2maxand VO2submax), peak knee torque, and flexibility. Subjects were 20 sixth grade boys, 11 of whom were members pf a YMCA soccer team; 9 were normally active boys who were not participating in any organized sport during the study who served'as a control group. Mean ages (+/-SD) were 11.8 +/- 0.34 and I; 1.5 +/- 0.60 yr for the soccer and control group, respectively. Initial VO2max values of 49.83 and 47.42 ml.kg-1-min-1 for the soccer and the control group, respectively, are similar to those reported in the literature for untrained normal boys of this age. Results indicated that playing soccer three times weekly increased VEmax and reduced VO2 (ml.kg-1.min-1 and|.min-1) at a submaximal running speed (all P's<0.O5), while no change in VO2max was noted. No significant training effect was observed in peak knee torque or flexibility subsequent to soccer training. It is concluded that the effects of playing soccer in these subjects resulted in no change in cardiprespiratory fitness, peak knee torque, or flexibility.
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Muscle glycogen degradation during simulation of a fatiguing soccer match in elite soccer players examined noninvasively by 13C-MRSx.
The influence of isokinetic muscle torque exerted in various speeds on soccer ball velocity.Numerous variables influence soccer kick performance and among those initial soccer ball velocity is considered to be important. The purpose of this study was to investigate the correlation between initial ball velocity and two physical characteristics: relative isokinetic torque of the lower extremity and muscle contraction velocity. Eleven elite Greek soccer players age 25.5 plus or minus 3 years, weight 73.6 plus or minus 5.6 kg, height 176.5 plus or minus 5.5 cm, were tested on an isokinetic apparatus at different angular velocities to determine isokinetic muscle torque of the dominant lower extremity. To determine muscle contraction velocity and initial soccer ball velocity a cycling ergometer and a photocell apparatus were used, respectively.
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lsokinetic Quadriceps and Hamstring Torque Levels of Adolescent, Female Soccer Players.Using a Cybex II(R) dynamometer, the quadriceps and hamstring torque levels of 16 female high school soccer players were measured. Both the dominant and nondominant knees were tested at a fast (1 80 per second) and slow (30 per second) speed. The results were similar to those of previous studies that used men as subjects. The conclusions were: 1) Extension torque is significantly greater than flexion torque for both legs and at both speeds. At 30 per second the hamstring1 quadriceps ratio is 0.6 1. This ratio increases to 0.78 at 180 per second. 2) There is no significant difference between dominant and nondominant legs for either flexion or extension torque at fast or slow speed. 3) At 30' per second, peak quadriceps torque is achieved at approximately 73 of extension, and peak flexion torque is achieved at approximately 38 flexion. 4) Slow speed flexion and extension torque levels are significantly greater than fast speed torque levels for both legs.
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The Relationship Between Onset of Blood Lactate Accumulation,Critical Velocity, and Maximal Lactate Steady State in Soccer PlayersThe objective of this study was to analyze the validity of the velocity corresponding to the onset of blood lactate accumulation (OBLA) and critical velocity (CV) to determine the maximal lactate steady state (MLSS) in soccer players. Twelve male soccer players (21.5 +/- 1.0 years) performed an incremental treadmill test for the determination of OBLA. The velocity corresponding to OBLA (3.5 mM of blood lactate) was determined through linear interpolation. The subjects returned to the laboratory on 7 occasions for the determination of MLSS and CV. The MLSS was determined from 5 treadmill runs of up to 30-minute duration and defined as the highest velocity at which blood lactate did not increase by more than 1 mM between minutes 10 and 30 of the constant velocity runs. The CV was determined by 2 maximal running efforts of 1,500 and 3,000 m performed on a 400-m running track. The CV was calculated as the slope of the linear regression of distance run versus time. Analysis of variance revealed no significant differences between OBLA (13.6 +/- 1.4 km[middle dot]h-1) and MLSS (13.1 +/- 1.2 km[middle dot]h-1) and between OBLA and CV (14.4 +/- 1.1 km[middle dot]h-1). The CV was significantly higher than the MLSS. There was a significant correlation between MLSS and OBLA (r = 0.80), MLSS and CV (r = 0.90), and OBLA and CV (r = 0.80). We can conclude that the OBLA can be utilized in soccer players to estimate the MLSS. In this group of athletes, however, CV does not represent a sustainable steady-state exercise intensity.
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Architectural characteristics of dominant leg muscles in junior soccer playersAbstract. The preferential use of dominant over non-dominant limbs produces muscle hypertrophy in the dominant limb. The purpose of this study was to investigate the architectural characteristics of the muscle that are associated with dominant leg use in junior soccer players. Fascicle length, pennation angle and muscle thickness of the medial gastrocnemius (MG) were measured by B-mode ultrasound in 26 junior soccer players [mean (SD) age: 16.5 (0.6) years] and 20 control college students [age: 18.5 (0.5) years]. Lower leg circumference and MG muscle thickness were significantly (P<0.05) greater in the soccer players than in the controls. The percent difference (dominant minus non-dominant legs) in muscle thickness and fascicle length were significantly (P<0.01) larger in the soccer players than in the controls, but the percent difference in pennation angle was similar between groups. The difference (dominant leg minus non-dominant leg) in muscle thickness was significantly correlated (r=0.55; P<0.05) with the difference in muscle fascicle length in the soccer players, but not in the controls (r=0.18). In conclusion, the preferential use of one limb over another, as seen in junior soccer players, results in a greater difference in muscle thickness between the dominant and non-dominant legs. This difference in muscle size was associated with longer fascicle lengths of the dominant leg. Thus, it appears possible that fascicle length may be further influenced by physical training in dominant legs.
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Analysis of passing sequences, shots and goals in soccerx.
EFFECTS OF A CARBOHYDRATE-ELECTROLYTE DRINK ON SPECIFIC SOCCER TESTS AND PERFORMANCEx.
An Ultrasound Speckle Tracking (Two-Dimensional Strain) Analysis of Myocardial Deformation in Professional Soccer Players Compared With Healthy Subjects and Hypertrophic Cardiomyopathyx.
ACTN3 genotype in professional soccer playersx.
Serum concentrations of two biochemical markers of brain tissue damage S-100B and neurone specific enolase are increased in elite female soccer players after a competitive gamex.
Carbohydrate and lipid requirements of soccer.Soccer involves high-intensity, intermittent exercise and places a heavy demand on the body's liver and muscle glycogen reserves. Thus, carbohydrate depletion may contribute, in part, to fatigue and reduced performance during a soccer match. In addition, fatty acids derived from both adipose tissue and intramuscular triglyceride stores will be utilized. Soccer players engaged in strenuous competition and training should be encouraged to consume a diet that is relatively high in carbohydrate (at least 55% of total energy intake). Furthermore, the inclusion of carbohydrate in beverages consumed during and after a soccer match is likely to enhance performance and facilitate the recovery of liver and muscle glycogen reserves.
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Protein intake and nitrogen balance in male non-active adolescents and soccer playersx.
Non-dominant leg training improves the bilateral motor performance of soccer playersx.
What shapes player performance in soccer? Empirical findings from a panel analysisIn this article, we investigate the pay-performance relationship of soccer players using individual data from eight seasons of the German soccer league Bundesliga. We find a nonlinear pay-performance relationship, indicating that salary does indeed affect individual performance. The results further show that player performance is affected not only by absolute income level but also by relative income position. An additional analysis of the performance impact of team effects provides evidence of a direct impact of team-mate attributes on individual player performance.
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Impact phase kinematics of instep kicking in soccerThe purpose of this study was to capture the lower limb kinematics before during and after ball impact of soccer kicking by examining the influence of both sampling rate and smoothing procedures. Nine male soccer players performed maximal instep kicks and the three-dimensional leg movements were captured at 1000 Hz. Angular and linear velocities and accelerations were determined using four different processing approaches: processed using a modified version of a time-frequency filtering algorithm (WGN), smoothed by a second-order low-pass Butterworth filter at 200 Hz cut-off (BWF), re-sampled at 250 Hz without smoothing (RSR) and re-sampled at 250 Hz but filtered by the same Butterworth filter at 10 Hz cut-off (RSF). The WGN approach appeared to establish representative kinematics, whereas the other procedures failed to remove noisy oscillation from the baseline of signal (BWF), lost the peaks of rapid changes (RSR) or produced totally distorted movement patterns (RSF). The results indicate that the procedures used by some previous studies may have been insufficient to adequately capture the lower limb motion near ball impact. We propose a new time-frequency filtering technique as a better way to smooth data whose frequency content varies dramatically.
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Lactate threshold responses to a season of professional British youth soccerx.
Nutritional intake of French soccer players at the clairefontaine training center.Young, French male athletes undergoing intensive elite sports training at the National Training Centre in Clairefontaine served as the subjects (N = 180; age range: 13 to 16 years) in a 3-year dietary survey aimed at characterizing their nutritional intake in terms of energy, macronutrients, calcium, and iron. Each year, the subjects were grouped by level into 3 promotions so that 9 groups could be studied. Dietary intake data were collected each year for each subject in the 9 groups, using a 5-day food record. The results showed that their total energy intake (TEI) was insufficient for athletes (ranging from 2352 454 to 3395 396 kcal/d as opposed to the recommended range of between 3819 and 5185 kcal/d). Furthermore, their diet was unbalanced, with too great an emphasis upon fatty foods (29.1 2.8 to 34.1 3.1% TEI vs. the 20% recommended), to the detriment of carbohydrates (48.5 4.3 to 56.6 3.1% TEI vs. the 55 to 60% recommended). The calcium intake was too low in 5 of the 9 groups while, in contrast, the iron intake was satisfactory in all groups. Furthermore, during this 3-year period at the Clairefontaine Centre, the subjects significantly (p <.05) improved their calcium and iron intakes (1021 197 and 12 2 mg/d in 1996, 1299 155 and 16 2 mg/d in 1997, and 1252 184 and 17 2 mg/d in 1998). This rise in micronutrient intakes may have been due to a physiological adaptation to growth or to the positive effects of courses on nutrition given during their stay at the Centre.
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Variability of acute physiological responses and performance profiles of youth soccer players in small-sided gameshttp://www.jssm.org
