If your heels don't touch the floor in your Yoga Squat, you've likely been told by to roll a blanket and stick it under your heels. Maybe you've been told your ankles or hips will open up over time. This is probably not true.
How to Correctly and Properly Assess a Client's Squat
Anatomy of the Powerlifting Squat - Temple of Iron
The main muscles involved in squatting.
How Hip Anatomy Affects Squat Mechanics – Squat University
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FreeFitnessGuru - Power Squat Anatomy Squat workout, Muscle fitness, Leg workout
How Hip Anatomy Affects Squat Mechanics – Squat University