When you start out, looking around you in a gym, everyone seems to lift heavy and you may want to try like them But don’t. If your mobility is poor, then you just hurt yourself, feel embarrassed and never want to go back to the gym again. I will help you during personal training, too.
Excessive tilt of a torso during Squat part1
Hamstring Tear by excessive tilt of a torso
To prevent muscle tears, perform either a specific stretching workout or incorporate hamstring stretches during a lifting workout between sets of squats and deadlifts and exercises for the back of the thigh.
Certain weight lifting exercises such as good mornings or stiff legged deadlifts, can be considered the best hamstring protectors because of their combined action of muscle strengthening and stretching.
Obviously you shouldn’t lift heavy to start with these exercises because the purpose of doing them here is to have better mobility / flexibility in hamstrings.
Another factor
An excessive tilt of the torso caused by possibly limited ankle flexibility. This is not only putting hamstrings in danger, but also the lower back to round when squatting low, increasing the danger of vertebral injuries.
Check to see some ankle mobility exercises here