http://www.assembla.com/spaces/talentid2009/documents/cN48bGVKer3OFEeJe5aVNr/download/0926BookinviteSelfSelectionofAthletesintosportsFinal.docThe crural indexThe skelic index describes leg length in relation to torso length and is defined as the derived total leg length (stature minus sitting height) divided by sitting height. These ratios are depicted in Figure 2.
Crural index & long/high jumping:Table 1. Here we show that while the computed somatotype components describe physique, the crural index (Davenport, 1933) represents an additional discriminant in describing physique variation across our adult sample. A dominant crural index in classes 2 and 4 illustrates the importance of relative limb length in athletes trained for endurance and strength. A smaller crural index may be advantageous for general agility, whereas a higher value may determine mechanically advantageous take-off technique in long-jump and high-jump events (Alexander, 1990) and in basketball, in tandem with development of commensurate muscle power to maximise femoral leverage Ackland et al., 1997).
Skeletal ratios
Significant differences in skeletal ratios are found between different types of
athletes even when differences in absolute body size are taken into account.
Marathoners tend to have a high skelic index (ratio of total leg length to
sitting height), that is, relatively longer legs. Distance runners also have a
higher crural index (ratio of lower leg length to upper leg length). Longer legs
reduce stride rate, and relatively shorter thighs mean that the resistance arm
on the upper leg is shorter. The muscle mass of the thigh is moved closer to
the axis of rotation of the leg, reducing the energy cost of locomotion.
http://lib-ir.lib.sfu.ca/bitstream/1892/7871/1/b16962849.pdfAnthropometric modelling of the human vertical jump
"A study of the proportions of animals of different species indicates that the
fast runners and jumpers are those that have long distal segments, such as
the horse, kangaroo, and the cat. The thigh segment of these animals is
short, ending before the segment leaves the pelvis or flank area The leg
segment is longer than the thigh; the foot segment is the longest, and the
toes are also quite long The animals described as the best jumpers have a
leg considerably longer than the thigh segment and therefore a large crural
index."
"Ross et al. (1982b) compared female high jumpers from the 1976 Montreal Olympic
Games to a group of Canadian reference females, and found that the high jumpers were
proportionally short in sitting height (in other words, proportionally long in the lower
extremities), and that the tibial length was also proportionally long. This supports the
notion that there is an advantage to having long lower extremities and a larger crural index
for jumping.
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