Stand with your back to a wall with your feet pointed straight ahead and placed shoulder-width apart. Keep your chest up as you hold a medicine ball with both hands at knee level. Lower yourself into a semi-squat position and jump off the ground explosively. Extend your arms overhead, rotating your torso and throwing the medicine ball over one shoulder. Make sure to release the medicine ball before your arms pass your ears and do not arch your back. Land with control and repeat, throwing the ball in the opposite direction.