Some people squat to parallel but just can't get down any further. Even if they religiously work on their hip mobility, VMO activation, and posterior chain flexibility, something still seems to block them from getting that extra range of motion. The fix for this can be as simple as foot position.
The Right Squat Stance
Many "rules" of squatting state that the lifter should place his or her feet just outside shoulder-width with toes turned slightly out. The truth is, not everyone's bone construction supports this. The hip joint is a ball and socket joint. The acetabulum (the "socket" located on the pelvis) where the femur links in isn't in the exact same place on everyone. Knowing this can tremendously affect the depth achieved in your squat.
If your acetabula are located more on the anterior, or front side of the pelvis, a narrower squat width would allow a greater ROM, as the femoral head will be properly placed in the socket and not blocked by being forced into an angled position with a wide stance.
Adversely, if your acetabula happen to be more towards the lateral sides of the pelvis, then a wider stance with toes pointing outwards will probably be best as far as achieving your full depth is concerned. Having your proper stance should be step one, then comes working on your relative flexibility and other muscle-related performance.
Here's the easiest way to figure out what foot width will work best for you in promoting the deepest squat you can get.
- After you finish stretching, find a mirror and get on your elbows and knees with the knees far apart.
- Keep a flat back and make sure your head and shoulders are closer to the floor than your hips are.
- Then, by slowly rocking backwards, push your butt towards your heels and take note of where your spine starts to curve.
- Repeat this test with a narrow knee and foot width and with a mid width. Keep playing around with different widths.
- You'll notice that you'll be able to keep a flat back for longer in a certain position versus others. Take this as an indicator of what your foot position should be when you squat.
Note: I've noticed that with many taller, long legged lifters, a slightly wider stance works best, whereas shorter-legged lifters benefit from a slightly narrower stance.