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Stability Ball Leg Curl

The Stability Ball Leg Curl is a bodyweight exercise that trains the back of the legs while challenging control and lower-body stability.

Stability ball

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Published: Apr 22, 2025 · Updated: Mar 15, 2026

The Stability Ball Leg Curl challenges the hamstrings and glutes while demanding constant core engagement to keep a rolling surface under control. Lying face up with your heels on the ball, you lift your hips and curl the ball toward you. Training on an unstable surface like a stability ball enhances joint stability and muscular coordination beyond what a fixed machine provides (Cao et al., 2025).

Keep your hips elevated throughout each rep. The hamstrings act as the primary mover during the curl, while the glutes maintain hip extension and the deep core muscles work to prevent lateral rolling. Exercises performed on unstable surfaces significantly increase activation of spine-stabilising muscles compared to stable-surface alternatives (Youdas et al., 2018).

This exercise fits well in lower-body sessions or as a hamstring-focused accessory after squats or deadlifts. Begin with two to three sets of 8 to 12 reps. To make it easier, keep the ball closer to your body; to make it harder, perform single-leg curls. Building hamstring and hip stability through exercises like this supports everyday activities such as stair descent and change-of-direction tasks (Kowalski et al., 2024).

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Technique and form

How to perform the Stability Ball Leg Curl

Lie on your back with your legs extended and heels on the stability ball, arms at your sides with palms facing down.
Engage your core by drawing your navel toward your spine and press your arms firmly into the floor for stability.
Exhale as you bend your knees, rolling the ball toward your body by contracting your hamstrings and lifting your hips slightly off the floor.
Continue pulling the ball inward until your feet are flat on the ball and your knees are bent at approximately 90 degrees, maintaining a neutral spine position.
Hold the contracted position for a moment while keeping your glutes engaged and your hips elevated slightly off the ground.
Inhale as you slowly straighten your legs, controlling the ball's movement away from your body without letting your hips drop.
Extend your legs completely while maintaining tension in your hamstrings and keeping your lower back pressed into the floor.
Perform the prescribed number of repetitions while maintaining a controlled tempo throughout the entire movement.

Important information

Keep your head, shoulders, and upper back in contact with the floor throughout the entire exercise to protect your neck and spine.
Avoid lifting your hips too high off the floor, as this shifts emphasis away from the hamstrings and can strain your lower back.
If you find the exercise too challenging, start with your knees bent at a 90-degree angle rather than fully extended.
Focus on moving the ball with your hamstrings rather than pushing with your feet to maximize muscle engagement.

Common Mistakes: Stability Ball Leg Curl

Rising on your toes

Keep your heels planted firmly on the ground throughout the movement. If your heels lift, work on ankle mobility or use a small plate under your heels.

Letting your knees cave inward

Push your knees out in the same direction as your toes. Collapsing knees puts dangerous stress on your knee joints.

Using too much weight

Isolation exercises are about feeling the muscle work, not lifting the heaviest weight possible. Pick a weight you can control for 10-15 reps.

Rushing through reps

Slow, controlled reps work the muscle much better than fast, sloppy ones. Take your time on both the lifting and lowering phase.

Holding your breath

Breathe out during the hard part of the movement and breathe in as you return to the start. Holding your breath can spike your blood pressure.

Benefits of the Stability Ball Leg Curl

Builds stronger back of your thighs (hamstrings)

The Stability Ball Leg Curl directly targets your back of your thighs (hamstrings), helping you build strength and size in this area over time.

Focused muscle targeting

As an isolation exercise, the Stability Ball Leg Curl lets you zero in on your back of your thighs (hamstrings) without other muscles taking over. This is great for bringing up a weak point or adding definition.

Increases overall strength

Regularly performing the Stability Ball Leg Curl with progressive weight builds functional strength that carries over to other exercises and daily life.

Equipment advantage

The stability ball forces your core to work harder to maintain balance, giving you a training benefit that's hard to replicate with other setups.

Train anywhere

The Stability Ball Leg Curl can be done at home with minimal or no equipment, making it easy to stay consistent even when you can't get to the gym.

Muscles Worked: Stability Ball Leg Curl

The Stability Ball Leg Curl is an isolation exercise that focuses your effort on the back of your thighs (hamstrings). Here's a breakdown of every muscle involved.

Primary muscles

Hamstrings — Your back of your thighs (hamstrings) control the lowering phase and assist the hips. These are the main muscle doing the heavy lifting during the Stability Ball Leg Curl.

Secondary muscles

Glutes — Your glute muscles generate hip power and keep your pelvis stable. While not the main focus, these muscles play an important supporting role.

The Stability Ball Leg Curl primarily works 1 muscle with 1 supporting muscle assisting the movement.

Risk Areas

Hamstrings

Muscles worked during the Stability Ball Leg Curl

FAQ - Stability Ball Leg Curl

What muscles does the Stability Ball Leg Curl target?

The Stability Ball Leg Curl primarily targets the hamstrings and glutes while also engaging the calves and core stabilizers. Your lower back and hip stabilizers also work isometrically to maintain proper position throughout the movement.

How can I make the Stability Ball Leg Curl easier or more challenging?

For an easier version, keep the ball closer to your hips and perform partial range of motion curls. To increase difficulty, position the ball further from your body, extend your arms out to the sides rather than using them for support, or progress to single-leg variations.

Is this exercise safe for people with knee or lower back issues?

The Stability Ball Leg Curl is generally considered lower-impact than loaded hamstring exercises like deadlifts, making it suitable for many rehabilitation programs. However, those with specific knee injuries or acute lower back pain should consult a physical therapist before attempting this movement.

What are the most common form mistakes to avoid?

The most common mistakes include rounding your lower back, rotating your hips instead of keeping them square, rushing through the movement, and not hinging properly at the hips. Focus on maintaining a neutral spine, moving with control, and keeping your standing knee slightly soft rather than locked.

How often should I include Exercise Ball Leg Curls in my training routine?

For optimal hamstring development, incorporate Exercise Ball Leg Curls 1-2 times weekly with 3-4 sets of 10-15 repetitions. Allow 48-72 hours between hamstring-focused workouts for proper recovery, especially if you're also performing other posterior chain exercises like deadlifts or Romanian deadlifts.

Scientific References

Evaluation of the Application of BOth Sides Up Ball Training Combined With Resistance Training in Joint Stability Improvement Following Anterior Cruciate Ligament Reconstruction Surgery in Teenage Athletes

Cao X, Liu J, Zhao J, et al. · J Sport Rehabil (2025)

Magnitudes of muscle activation of spine stabilizers in healthy adults during prone on elbow planking exercises with and without a fitness ball

Youdas JW, Coleman KC, Holstad EE, et al. · Physiother Theory Pract (2018)

Muscle Activity and Biomechanics While Descending a Staircase After Total Knee Arthroplasty: A Study Comparing Different Posterior Stabilized and Medial Ball-and-Socket Designs

Kowalski E, Pelegrinelli ARM, Ryan N, et al. · J Arthroplasty (2024)

Sources are peer-reviewed academic publications from PubMed.

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Workouts with Stability Ball Leg Curl

Best Hamstring workouts

Hamstring workouts focus on the powerful muscles along the back of your thighs, which are key for running, jumping, and lifting. These workouts combine hip-dominant movements like Romanian deadlifts with knee-dominant exercises like leg curls to target the full length of the muscle. Strong hamstrings help prevent injuries, improve posture, and increase power in both sports and everyday movements. Whether you're training for speed, stability, or size, developing your hamstrings is essential for lower body performance.