The stability ball back extension works your legs and glutes.
Stability Ball Back Extension Form Cue
Come into a prone position on the stability ball (on your stomach), with the ball just above hip level. Place your hands either crossed at your chest or behind your head (more challenging). Ground through your hips and feet, contract your core to exhale and come into your back extension. Just aim for a straight spine and avoid hyperextending your back. Gently lower down to repeat. If it’s your first time doing these, I recommend one set to start and that’s it. You will likely be sore from just a little bit and it’s better to start small and work up from there.