Tight hips? Besides being uncomfortable, it can lead to back pain. When your flexors are tight you will have a tendency to lean forward while squatting. A forward lean will shift your center of gravity anteriorly and increase activation of your quadriceps while decreasing activation of your glutes. As a result, when you stand up your flexors are going to stay shortened, which will contribute to an anterior pelvic tilt and make it really difficult to adequately activate the posterior hip muscles. Basically, you need to stretch!!