Gym Ball Hamstring Curl
You lie on your back with your heels on a gym ball and your hips extended, so your shoulders, hips and heels form one line. From there you slowly pull the ball towards you as far as you can, then slowly roll it back out. Your hips stay at the same height the whole time.
This exercise trains your hamstrings, the muscles at the back of your thighs. They pull the ball in towards you and control it on the way back out. Meanwhile your glutes and trunk keep your hips up, so they stay up while the ball rolls.
All you need is a gym ball and a bit of floor space. That makes it a good way into hamstring training — bodyweight only, at a pace you set yourself.
The exercise is all about a slow tempo in both directions: slowly in, slowly out.
Starting position
Sit in front of the ball and place your feet on it hip-width apart, heels on top. Then lower your back to the floor. Your arms rest out to the sides for support — or bend them and rest your hands on your chest.
Now lift your hips until your shoulders, hips and heels form one line. Pull your toes up towards your shins.
From that line, slowly pull the ball in towards your bottom as far as you can, then slowly roll it back out until your legs are straight. Your hips stay at the same height the whole time.
The three cues
- Feet hip-width on the ball, lift your hips until shoulders, hips and heels form one line
- Toes up, then pull the ball in slowly, as far as you can — and slowly back out
- Your hips stay at the same height all the way through
Common faults
| Fault | How to fix it |
|---|---|
| Your hips drop as soon as you pull the ball in | Reset the line from shoulders to heels before every rep. Better to pull the ball in a little less and keep your hips up. |
| Your hips rise as you pull the ball in | In the basic version your hips stay at the same height. Letting them rise is the harder level — save it for when the basic version is solid. |
| The ball rushes in or rolls back out of control | Slowly in, slowly out. If the ball speeds up, shorten the range until you are guiding it both ways. |
| You only roll the ball a short way | Use the full range: in as far as you can, and back out until your legs are straight — with your hips up. |
| Your toes are pointed away from you | Pull your toes up towards your shins. Your heels sit on top of the ball. |
| The ball drifts to one side | Place your feet hip-width apart with even pressure on the ball, and pull with both legs equally. |
Variations
| Variation | When to use it |
|---|---|
| Arms on the floor | Your arms rest out to the sides for support. That makes it easier to keep your hips up, so you can focus entirely on the ball's path. |
| Hips stay at the same height | Arms bent, hands resting on your chest. Pull the ball in slowly as far as you can and roll it slowly back out — your hips stay at the same height throughout. |
| Hips rise as you curl | As you pull the ball in, your hips rise with it, so your shoulders, hips and knees stay in one line and only your knees bend. It's much tougher on the hamstrings: the next step once the basic version is solid through the full range. |
Reps and load
Slow in both directions, hips up the whole time. In each set, do as many reps as you can with the same hip height and the full range — that's where the set ends.
The exercise works with your bodyweight alone and sits well alongside hinge exercises such as the Romanian deadlift or the hip thrust.
Which muscles do the work
| Muscle | Role | What it does here |
|---|---|---|
| Hamstrings Mm. ischiocrurales | Prime mover | Bend the knee, pull the ball in and control it on the way back out |
| Calves M. gastrocnemius | Synergist | Help bend the knee |
| Glute max M. gluteus maximus | Stabiliser | Keeps your hips up while the ball rolls |
| Glute med M. gluteus medius | Stabiliser | Keeps your pelvis level when the ball tries to drift sideways |
| Spinal erectors M. erector spinae | Stabiliser | Work with the glutes to keep your hips up |
| Abs M. rectus abdominis | Stabiliser | Stop your lower back arching while your hips are up |
| Obliques Mm. obliqui abdominis | Stabiliser | Keep your pelvis steady while the ball rolls under your heels |
The hamstrings do the moving; everything else holds. Your glutes, spinal erectors and abs keep your hips up while the ball rolls — which is why you feel this in your glutes and trunk too.
Explained in full
Andreas sets up on the ball: feet hip-width, hips up into one line, toes pulled up, then slowly in and back out. He also shows the basic version, where your hips stay at the same height, and the harder one, where they rise as you curl. · 1:00
Seeing it done right is not the same as doing it right
Video, cues and variations take you a long way. What they cannot give you is an outside eye at the moment the movement isn't quite there yet. That is what training with me is for — in the studio or in a workshop.
See the workshopsNew exercise pages are added all the time — the newsletter keeps you posted.
Sources
Guruhan S, Kafa N, Ecemis ZB, Guzel NA. (2021). Muscle Activation Differences During Eccentric Hamstring Exercises. Sports Health 13(2):181–186. DOI: 10.1177/1941738120938649 — Compares four eccentric hamstring exercises in 31 healthy adults (18 men, mean age 22.5, untrained according to the full text): the stiff-leg deadlift, its single-leg version, the Nordic hamstring curl and the ball leg curl. The Nordic hamstring curl produced the highest activity (P < 0.001). The authors recommend the ball leg curl and both deadlift variations for the start of a strength programme because they are less demanding. The basis for placing this exercise as a way into hamstring training. Ball leg curl values appear only in a figure, so no number is given here. There is no measurement specific to the Academy's target group (aged 40 to 60, training two to four hours a week). (Evidence type: EMG)
Monajati A, Larumbe-Zabala E, Goss-Sampson M, Naclerio F. (2017). Analysis of the Hamstring Muscle Activation During two Injury Prevention Exercises. J Hum Kinet 60:29–37. DOI: 10.1515/hukin-2017-0105 — Measures the hamstrings in the Nordic hamstring curl and the ball leg curl in 10 female football players (mean age 22, resistance-trained) — in the version where the pelvis rises as the ball comes in, i.e. this page's harder level. Both parts of the hamstrings (biceps femoris and semitendinosus) worked equally hard. Near full knee extension the Nordic hamstring curl was higher (biceps femoris 74.8 vs 50.3% MVIC, semitendinosus 78.3 vs 44.3%). The basis for listing the hamstrings as the prime mover. A very small, young, athletic sample; glutes and trunk were not measured. (Evidence type: EMG)
Hirose N, Tsuruike M. (2018). Differences in the Electromyographic Activity of the Hamstring, Gluteus Maximus, and Erector Spinae Muscles in a Variety of Kinetic Changes. J Strength Cond Res 32(12):3357–3363. DOI: 10.1519/JSC.0000000000002747 — Measures the hamstrings, glute max and spinal erectors in 16 men during knee flexion and in two-leg and one-leg bridges, each at 30, 60, 90 and 120 degrees of knee bend, held isometrically. In the bridges the spinal erectors followed the same pattern as the hamstrings, and glute max stayed consistently involved across all knee angles. The basis for listing the glutes and spinal erectors as stabilisers that keep your hips up. Measured on the floor without a ball or movement; age not stated in the abstract. (Evidence type: EMG)
Lehman GJ, Hoda W, Oliver S. (2005). Trunk muscle activity during bridging exercises on and off a Swiss ball. Chiropr Osteopat 13:14. DOI: 10.1186/1746-1340-13-14 — Measures, in college students, rectus abdominis, the obliques and the lower spinal erectors in bridging exercises on and off a Swiss ball, including the supine bridge with the feet on the ball. All four muscles were active in these bridges; adding the ball did not change their activity. The basis for listing the abs and obliques as stabilisers. Held without knee bend, glutes not measured, young sample. (Evidence type: EMG)
Marchetti PH, Magalhaes RA, Gomes WA, da Silva JJ, Stecyk SD, Whiting WC. (2021). Different Knee and Ankle Positions Affect Force and Muscle Activation During Prone Leg Curl in Trained Subjects. J Strength Cond Res 35(12):3322–3326. DOI: 10.1519/JSC.0000000000003333 — Measures force and muscle activity during a maximal isometric prone leg curl at different knee and ankle positions in 15 resistance-trained men (27 ± 4 years). The lateral gastrocnemius was most active at 90 degrees of knee bend with the ankle pulled up (dorsiflexed); hamstring activity did not change with knee or ankle position. The basis for listing the calf as a synergist in bending the knee. Prone machine, young men. (Evidence type: EMG)
A note on context: EMG studies show which muscles an exercise recruits — that is a good reason to pick it, but it does not replace adjusting things to the person in front of you. See a doctor for persistent or severe pain.