The iliopsoas, aka hip flexor, is. a commonly overlooked contributor to low back pain and hip pain. The muscle is often perceived as tight, not because it is overworked, but quite the opposite, it is underworked. That can lead to muscles of the lower back to overcompensate which creates a neurologic imbalance and shearing or pain in the joints. If you sit, or do a lot of hip flexion activities such as squats, deadlifts, lunges, and cycling, these are great to do before and after a workout.