Seated One Leg Curl

Muscle Hamstrings

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How to do the Seated One Leg Curl

The Seated One Leg Curl is a unilateral hamstring isolation exercise that focuses on strengthening and balancing the muscles at the back of the thigh. Performed on a seated leg curl machine, it works through controlled knee flexion, allowing one leg to train independently. This setup helps correct strength imbalances, enhances muscle activation, and promotes better neuromuscular control throughout the movement.

Because the exercise isolates one leg at a time, it ensures equal effort between limbs and helps address discrepancies that can develop during bilateral lower-body training. The seated position also stabilizes the hips and reduces the risk of compensation from the glutes or lower back, allowing the hamstrings to perform most of the work.

To execute the exercise, sit upright with your back firmly against the pad, and place one ankle beneath the roller. Curl the heel toward your glutes in a slow, controlled motion, focusing on contracting the hamstrings at the top of the movement. Lower the leg gradually to feel a full stretch and maintain muscle tension throughout the range of motion. This eccentric control is key to improving both strength and flexibility.

In addition to targeting the hamstrings, the Seated One Leg Curl engages the glutes and calves as stabilizers, contributing to overall lower-body symmetry and knee stability. It’s especially beneficial for athletes, bodybuilders, and individuals rehabbing injuries, as it helps reinforce the posterior chain and reduces the risk of strain or imbalance-related injuries.

For best results, prioritize form, control, and range of motion over heavy loading. The Seated One Leg Curl is suitable for intermediate and advanced lifters aiming to improve hamstring strength, muscle tone, and joint health while minimizing stress on the lower back and hips.

Primary Muscle: Hamstrings
Secondary Muscles: CalvesGlutes
Equipment: Machine
Difficulty: Intermediate

Setup Instructions

Adjust the seated leg curl machine so that the back pad supports your lower back and the leg pad rests just above your ankles.
Sit down and align your knee joint with the machine’s pivot point for optimal biomechanics.
Select a moderate weight that allows controlled, full-range motion for one leg at a time.
Place one leg under the padded lever while keeping the other leg relaxed off to the side or on the platform.
Grip the handles beside the seat to maintain stability during the movement.

Coaching Cues

Keep your back firmly pressed into the seat to prevent movement through the hips.
Control the eccentric (lowering) phase to maximize hamstring engagement.
Focus on isolating one leg at a time to correct strength imbalances.
Avoid locking your knee at the top or bottom of the motion.
Breathe steadily — exhale as you curl, inhale as you extend.

Execution Steps

Begin by flexing the working leg, curling your heel down and back toward your glutes in a slow and controlled manner.
Continue curling until your knee is fully flexed or you reach the machine’s range limit.
Pause briefly at the top of the movement and contract your hamstring muscles.
Slowly extend the leg back to the starting position, maintaining tension throughout the descent.
Complete all repetitions on one side before switching to the opposite leg.

Common Mistakes

Using excessive momentum instead of controlled movement.
Allowing the hips or torso to shift during the curl.
Neglecting the full range of motion, especially the stretch at the bottom.
Selecting too heavy a weight that compromises technique.
Failing to maintain even control between both legs.

Safety Notes

Always warm up your hamstrings before heavy sets to prevent muscle strain.
Ensure the machine’s alignment matches your knee joint to reduce stress on ligaments.
Avoid jerky or rapid movements that may strain the hamstring tendons.
Maintain a slow, controlled motion throughout both phases of the lift.
If discomfort arises in the knee or hip, stop immediately and reassess your setup.