Most people think that the main problem with squat depth is hamstring extensibility, more
commonly referred to as “flexibility” – the ability of the hamstrings to lengthen as the depth of the
squat increases. This is not really necessary, and loose, elastic hamstrings are not the key to a deep squat.
Optimal skeletal mechanics is.
If you stand with your heels at shoulder-width apart and point your toes out at about 30
degrees, squat down, and keep your thighs parallel to your feet, then as your hip angle closes and
your thighs approach your torso, your femurs will track to a position that is outside of the ASIS – the
anterior superior iliac spine – the hip pointer that you feel right below your waistline. But if you point
your toes straight forward and let your knees follow your toes, or even if you point your toes out but
still let your knees cave in toward the middle when you squat, then as you squat down your femur will
approach the ASIS as you approach the bottom. So as your thighs crowd your belly, they tend to trap
any soft-tissue structures that may be in the area between the thigh and the hip pointer. If you have a
big gut or big thighs, or a lot of clothes on, this will keep you from obtaining a below-parallel squat.
Squat depth is a function of hip angle, the angle formed between the generalized plane of the
torso and the femur. If you try to continue to drop down to get better depth with no adjustment in
the position of your femurs, it will happen at the expense of a rounded lower back, since the hip angle
cannot become more acute if the femur is impinged. If the pelvis – which is supposed to be locked
into the lordotic curve with the lumbar vertebrae, held rigid by the erector spinae muscles – can’t tilt
forward to maintain this position because it rams into an obstruction formed by the impinged femur,
the only way to keep going deeper is to round the low back into lumbar flexion. The obstruction occurs
before the bones actually touch, of course, since the hip flexor origins lie in between. Everybody, big
belly or not, will experience this phenomenon to one degree or another, and everybody that cannot
get below parallel with an arched low back has this problem. If you’re having depth problems, shoving
the knees out fixes it so often that it is waste of time to do anything else first.
