Ball Leg Curl
The ball leg curl has you lying on your back with your heels resting on a stability ball, lifting your hips off the floor and then curling the ball toward your glutes by bending your knees. It trains the hamstrings as the primary mover, with the calves and glutes assisting, and the added instability of the ball means your core and hips have to stay braced the entire time just to keep from wobbling off balance.
Why it works
A standard hamstring exercise like a machine leg curl fixes your hips in place and isolates the knee bend. The ball leg curl asks for both at once: your hips must stay lifted and level throughout the set while your hamstrings curl a rolling, unstable ball toward your body. That combination trains the hamstrings through their full range while also demanding real hip stability and core control, which is closer to how these muscles actually work together during running and other athletic movement.
Set up
- Lie on your back with your heels resting on top of a stability ball, legs extended.
- Rest your arms flat on the floor at your sides for support.
- Lift your hips off the floor until your body forms a straight line from shoulders to heels.
How to do it
- Keeping your hips lifted, bend your knees to roll the ball toward your glutes.
- Keep your hips level and steady throughout the curling motion.
- Pause briefly once the ball is pulled in close.
- Extend your legs back out slowly, rolling the ball away with control.
- Keep your hips elevated for the entire set, not just during the curl itself.
- Lower your hips to the floor to rest between sets.
Form cues
- Hips stay lifted the whole set.
- Curl comes from the knees, hips stay steady.
- Slow, controlled roll in both directions.
- Core braced to prevent wobbling.
Breathing: Exhale as you curl the ball in toward your glutes, inhale as you extend your legs back out.
Common mistakes
Letting the hips drop toward the floor during the curl.
Fix: Keep your glutes squeezed and your hips lifted throughout; if they keep dropping, shorten the range or build hip strength with the glute bridge first.
Rushing the ball back and forth instead of controlling both directions.
Fix: Slow the tempo down significantly; the ball's instability rewards control far more than speed.
Letting the ball roll side to side instead of straight in and out.
Fix: Keep your legs and hips square, curling the ball in a straight line toward your glutes rather than allowing it to drift.
Attempting this exercise before basic hip bridging strength is solid.
Fix: Build a foundation with the standard glute bridge first, since this exercise adds instability on top of a similar hip-lifted position.
How to program it
- Start with 2 or 3 sets of 8 to 10 reps, two or three days a week.
- It works well as a hamstring-focused finisher after squats or deadlifts, or as a stability-focused core and leg exercise on its own.
- Progress by slowing the tempo or adding a pause at the curled position before trying a single-leg version.
- Pairs well with a quad-dominant exercise like the squat in the same session for balanced leg training.
Safety notes
- Use a properly inflated, non-slip ball on a stable surface to reduce the chance of it sliding away unexpectedly.
- If your hips keep sagging or your lower back arches, shorten the range or return to the standard glute bridge until hip strength improves.
Exercise profile
- Force
- Pull
- Mechanics
- Isolation
- Category
- Strength
Frequently asked questions
What muscles does the ball leg curl work?
The hamstrings drive the curling motion, with the calves assisting to control the ball and the glutes working to keep your hips lifted throughout the set.
How many ball leg curls should I do?
Eight to ten reps, for 2 or 3 sets, is a solid starting point. Prioritize keeping your hips level and controlled over chasing a high rep count.
Why do my hips keep dropping during this exercise?
This usually means your hip and glute strength isn't quite ready for the added instability yet. Build a foundation with the standard glute bridge, then return to this exercise once that feels solid.
Ball leg curl vs machine leg curl: which is better?
The machine leg curl isolates the hamstrings with a fixed, heavier resistance path. The ball leg curl uses bodyweight but adds a real hip stability and core challenge. Many programs use both for different qualities of hamstring training.