Leg Curl

What is the Leg Curl?

The lying leg curl is a machine isolation exercise that trains the hamstrings purely through knee flexion. You lie face-down and curl the pad toward your glutes against a resistance arm, which lets you hammer the hamstrings hard without any hip-hinge or lower-back demand.

Muscles worked

Primary: Hamstrings

The hamstrings are the sole prime mover, contracting to bend the knee and drag the pad toward the glutes with the hips fixed flat on the bench.

How to perform the Leg Curl

1. Lie face down on the lying leg curl pad with the ankle roller sitting just above the heels on the Achilles, not on the calf.
2. Adjust the pad so the knee joint lines up with the machine pivot, then grip the handles and press the hips down into the bench.
3. Because the hips stay flat and extended, this loads the hamstrings as pure knee flexors with a short starting stretch.
4. Curl the roller up toward the glutes by flexing at the knees, keeping the hips pinned to the pad throughout.
5. Squeeze the hamstrings hard at the top where the knees are fully flexed and the roller is close to the glutes.
6. Lower the roller under control back to a near-straight knee, resisting the weight rather than letting it drop.

Suggested working range: 10–15 reps. Default progression: double progression.

Mechanics

A single-joint isolation built entirely around knee flexion: the hips stay pinned to the pad so the only action is the knee bending against the resistance arm. Because the hip never moves, it targets the knee-flexion function of the hamstrings that hip-hinge lifts largely miss.

Form cues

• •Lie flat and keep your hips pressed into the pad: letting them pop up turns it into a cheat and takes tension off the hamstrings.
• •Curl all the way until the pad nearly reaches your glutes, then lower under control rather than letting it slam back.
• •Point your toes or flex them consistently, but do not kick with your feet. Drive the movement from the back of the knee.

Common mistakes

• •Letting the hips pop up off the pad to swing the weight up with lower-back extension.
• •Using momentum to fling the roller up instead of curling slowly through the knee flexion.
• •Cutting the eccentric short by dropping the weight instead of lowering under control.
• •Placing the ankle roller too high on the calf, which shifts leverage off the hamstrings.

Variations & alternatives

• •Seated leg curl: the same knee-flexion movement with the hip flexed, which lengthens the hamstring and often hits harder.
• •Single-leg curl: one leg at a time to find and fix a strength imbalance between sides.
• •Nordic hamstring curl: a brutal bodyweight knee-flexion movement that overloads the eccentric for injury resilience.

Romanian Deadlift

Hamstrings · Barbell

Dumbbell Romanian Deadlift

Hamstrings · Dumbbell

Single-Leg Curl

Hamstrings · Machine

Nordic Hamstring Curl

Hamstrings · Bodyweight

Glute-Ham Raise

Hamstrings · Machine

Programming: sets, reps & when to use it

Run the lying leg curl for 10–15 reps as a hamstring isolation accessory after your hinges and squats. It pairs perfectly with an RDL: the hinge trains hip extension, the curl covers the knee-flexion job the hinge barely touches.

Frequently asked questions