Full title: THe right and wrong way to squat: most people reading this squat the wrong way.
I'm going to make this really short, but after a few responses I'll get more detailed.
Almost everyone I see in the gym does the useless type of squat for athleticism: you can call it the
toe-to-heel squat. Weak glutes, laziness, ego and resultant desire to stack more plates on the bar, tight adductors/hipflexors, are all potential contributors to this calamity plaguing athletes every hour of the day.
When I teach people how to squat (as the bona fide personal trainer I am), most people will initially descend on toes and ascend shifting to heels, performing this evil toe-to-heel squat. As a result, I came up with (as plenty of other moderately intelligent men and women have), of teaching a heel-to-toe squat. Descend, focusing on heels, ascend, rising on toes. Works wonders.
It's important to understand the importance of this because many people who get interested in jumping higher subsequently become interested in weight lifting, and many waste their time due to incorrect form, and then lose interest in vertical jump and cease to see any gains so instead just focus on strength training. I've seen plenty of 'impressive' squat videos on this forum that are unfortunately toe-to-heel evil squats; and the athletes squatting this way usually have a poor vertical jump because this type of squatting won't transfer as well to VJ.
Here is a toe to heel squat:
http://www.youtube.com/watch?v=rTk7azSIAXQat 00:11, she is on her toes, at 00:12, she shifts her weight back onto her entire foot, and then shifts back to toe.
Concomitant with toe-heel mechanics are the positions of the knee and hip joints; the knee and hip tend to move in directions that they would not during athletic events in a vertical (coronal), or horizontal (sagittal) planes.
Compare the way her hips and knees move in relation to her box jumping:
http://www.youtube.com/watch?v=Y0hgELLBI08In weight lifting, since the planes are slightly more restricted, the knees of toe-to-heel (to be called toe squatters from now on) push back tremendously. Notice in the squat video, that while her knees move back, her hips also move back.
THis would be good if the athlete wanted to improve her ability to jump backwards.It's easier to lift more weight this way though for sure and that's why people do it.
Here is another example of toe squatting
http://www.youtube.com/watch?v=kLnUDaxMmnUThe video I was looking for though was when frank yang literally jumped backwards after a max squat, throwing the bar in front of him... That wouldn't be possible if he were heel squatting, and transferring the forces to the toes, and extending more at the hip, because HE would be moving forwards slightly with the bar. Toe squatters move backwards, and this creates a nice levrage to lift more weight up. THe clearest evidence is in the knees, they come forward, and move back exaggeratedly as I mentioned earlier. Of course the knees do that in a vertical jump as well because that is how knee extension works in the coronal plane, but not as much. And NOBODY vertical jumps descending on their toes and ascending on their heels or some part of the foot behind the toes.
Of coruse frank could jump high, but I am confident he'd be able to jump higher if he could squat the same numbers with the form I recommend... the same form everyone recommends in fact. It's natural to transfer weight forward whether it's walking, running, or jumping. I've taken videos of my deadlifts and noticed I fail to get back on my heels during the eccentric wth 70% of greater of 1rm. It's weakness.
The challenge then arises: who can jump the highest, with the weakest squat? (assuming you weren't naturally jumping freakishly high, also assuming the squat is the heel-to-toe correct squat of course). Those wth strong squat who cannot jump high are probably doing toe to heel squats.
Lastly, you'll immediately feel a difference in recruited musculature after doing it correctly.