Stability Ball Hamstring Curls
How to: Using a stability ball, lay on your back placing both heels on the center of the stability ball. Elevate your hips off the floor driving through your gluteals (butt muscles), creating a straight line through your ankles, knees, hips and shoulders. Slowly roll the ball in towards your butt by engaging your hamstrings, then slowly roll the ball back to the starting position. Focus on your hamstrings, keeping your navel drawn-inwards and not dropping your hips.