The stability ball hamstring curl works – you guessed it – the hamstrings!
Stability Ball Hamstring Curl Form Cue
Lie onto your back and place your feet on the ball. Engage your glutes to lift your hips off the floor. Bend your knees to bring your heels towards your glutes before extending your legs back out. Keep your hips lifted the entire time. For a challenge: try one leg at a time.