If a client's hips drop toward the floor during push-ups, it is typically due to poor core stabilization, especially weakness in the abdominals (rectus abdominis, transverse abdominis, and obliques) and sometimes the glutes.
These muscles stabilize the lumbopelvic-hip complex (LPHC), preventing excessive lumbar extension and anterior pelvic tilt. NASM emphasizes that the local stabilization system-including the transverse abdominis and multifidus-must contract isometrically to maintain a neutral spine. Strengthening these muscles through anti-extension core exercises (e.g., planks, stability ball rollouts) will help correct this push-up compensation.