When performing a supine leg raise, what muscle is the prime mover?

In a supine leg raise, the prime mover is the psoas major muscle. This muscle plays a crucial role in hip flexion, which is the primary movement occurring during a leg raise while lying on your back. As you lift your legs towards the ceiling, the psoas major contracts to bring the thighs closer to your torso, effectively lifting the legs off the ground.

The rectus abdominis does contribute to stabilizing the core during the movement, but it is not the primary muscle responsible for the action of lifting the legs. The vastus medialis is involved in knee extension rather than hip flexion, and while the gluteus maximus is important for hip extension and stabilization of the pelvis, it is not the key muscle engaged in a leg raise. Understanding this muscle action is important for proper exercise execution and preventing injury.