Intermediate

Swiss-Ball Leg Curl

Lying on your back with heels on a ball, you bridge the hips up and roll the ball in, so the hamstrings both extend the hip and flex the knee. The unstable ball forces the whole posterior chain to stabilize while it works. It is a superb bodyweight builder and a common test of hamstring strength endurance.

Body part
Hamstring
Type
Balance, Strength
Browse by movement
Hinge, Knee Flexion
Muscles worked
Target
Biceps Femoris, Semitendinosus
Secondary
Gluteus Maximus, Gastrocnemius Medial Head, Gastrocnemius Lateral Head
Tertiary
Erector Spinae

How to do it

  1. 1

    Lie on your back with your heels and lower calves on top of the ball.

  2. 2

    Set your arms flat at your sides for a stable base.

  3. 3

    Drive your hips up into a straight-line bridge.

  4. 4

    Bend your knees to roll the ball in toward your glutes.

  5. 5

    Keep the hips high as you pull, then extend the legs back out slowly.

  6. 6

    Lower the hips only after the ball returns to the start.

Tips

  • Keep your hips lifted the entire set; sagging shifts the work off the hamstrings.
  • Widen your arms if you need more balance early on.
  • Progress by curling with one leg once both feel easy.

Variations

Common mistakes

  • Resting the arches of your feet on the ball instead of the heels and lower calves lets it squirt out from under you as soon as you pull. The heels are what hook the ball in.
  • Rolling the ball a few inches and pushing it straight back keeps you in the easy middle of the range. Pull until your heels are close under your glutes and extend until the knees are almost straight.
  • Driving your head and shoulders into the floor to hold the bridge up stiffens the neck and takes work off the hamstrings. Your weight belongs on the upper back and arms.
  • Hamstring cramp is common in the first few sessions. If the muscle grips, lower your hips, straighten the legs, and shorten the range on the next set rather than pushing on through it.
  • Doing these in socks on a smooth floor lets the ball skate sideways mid-rep. Train on a mat or carpet where it stays where you put it.

Frequently asked

How many sets and reps of the swiss-ball leg curl should you do when you are new to the exercise?
Three sets of 8 to 12, ending each set when your hips start to sag rather than at a set number. If 8 clean reps are out of reach, hold the bridge with the ball still for 20 to 30 seconds instead, then start adding curls once that is comfortable. Progress by building to 12 reps, then slowing the roll-out to three seconds, then moving to one leg. Twice a week fits nicely after a hinge, since it needs no extra load.
How do I make the swiss-ball leg curl easier or harder?
To make it easier, spread your arms wide on the floor, keep the hips a little lower, or shorten the roll-out to half the range. Curling with your hips resting on the floor between reps removes the bridge and leaves only the knee flexion. To make it harder, fold your arms across your chest, take three or four seconds to extend the legs, pause with the legs straight and the hips high, or lift one foot and curl with a single leg. A smaller, firmer ball is also harder than a big soft one, since it gives the heels less to hook onto.
What is the swiss-ball leg curl good for and when should I choose something else?
It trains both jobs of the hamstring at once, bridging the hip and bending the knee, using nothing but a ball, which makes it a strong home option and a common test of hamstring endurance. It suits beginners, home trainers and anyone adding hamstring work without loading the spine. Choose something else when you want to progress in measurable steps, because body weight is the only load here and once 15 clean reps are easy the only ways forward are one leg or a slower tempo.

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