Unfortunately for the majority of people they aren’t even stretching their hamstring, they are instead stretching their sciatic nerve. And just incase you didn’t know stretching nerves is a really bad idea.
Poor hip mobility is without a doubt a cause for not being able to achieve a biomechanically sound squat. Where do we start then? I always start by addressing athletes hip INTERNAL rotation.
External rotation and flexion of the hip are easy and hip internal rotation is a better predictor of overall hip health.