The lying leg curl is one of the most effective ways to isolate your hamstrings, the muscles running down the back of your thigh. Lying face down on the machine, you hook your ankles under a padded lever and curl your heels toward your glutes, working knee flexion through a full range with almost no involvement from other muscle groups. Because the machine guides the path and supports your torso, it's beginner-friendly and easy to load progressively. Squats and deadlifts hit the hamstrings as hip extensors, but the lying leg curl is one of the few moves that trains their second job: bending the knee. That makes it a smart addition for balanced leg development and knee health.
How to do the lying leg curl
- Adjust the machine so the rotating axis of the lever lines up with your knee joint, and the ankle pad sits just above your heels on the back of your lower shin.
- Lie face down with your hips flat on the bench, knees just off the edge of the pad, and grip the handles to anchor your upper body.
- Set your feet roughly hip-width with toes pointed straight or slightly down, and take the slack out of the cable or weight stack.
- Curl your heels toward your glutes by bending your knees, driving through the ankle pad while keeping your hips pressed firmly into the bench.
- Pause for a beat at the top, where your hamstrings are fully contracted, and consciously squeeze the muscle.
- Lower the weight slowly and under control back to the start, resisting the lever rather than letting it drop, until your knees are nearly straight.
- Repeat for your target reps, keeping the tempo smooth and the motion driven entirely from the knees.
Muscles worked
The primary muscle worked in the lying leg curl is the hamstrings, the group on the back of the thigh made up of the biceps femoris, semitendinosus, and semimembranosus. These muscles are responsible for knee flexion, which is exactly the movement the curl trains as you draw your heels toward your glutes against resistance. The calves, specifically the gastrocnemius, assist as secondary movers because that muscle crosses the back of the knee and contributes to flexion. Your foot position changes the emphasis: pointing the toes down (plantarflexion) lets the gastrocnemius help more, while pulling the toes up toward your shins biases the hamstrings. The lower back and glutes stay relatively passive when form is correct.
Benefits
- Directly isolates the hamstrings through knee flexion, a function squats and deadlifts largely miss.
- Beginner-friendly and low-skill: the machine guides the path and supports your spine, so there's little to coordinate.
- Easy to load and progress incrementally, making it ideal for building hamstring size and strength over time.
- Strengthens the muscles that stabilize and protect the knee, supporting balanced quad-to-hamstring development.
- Low spinal loading compared to free-weight hamstring work, so it's gentler on the lower back.
Common mistakes
- Lifting the hips off the pad: anchor your hips down so you isolate the hamstrings instead of swinging the weight up with momentum.
- Using too much weight: reduce the load so you can complete a full, controlled rep without jerking or arching.
- Rushing the negative: lower over 2 to 3 seconds, since the lengthening phase is where much of the hamstring growth happens.
- Cutting the range short: curl as far up as your knees allow and extend nearly straight at the bottom for full-range tension.
- Misaligned knee pivot: line your knee joint up with the machine's axis, or the resistance fights your joint instead of your muscle.
- Holding your breath and clenching: keep breathing and let the knees do the work rather than your neck and shoulders.
Form tips
- Press your hips and pelvis firmly into the bench throughout every rep to keep tension on the hamstrings.
- Squeeze hard at the top for a brief pause, where the hamstring contraction is strongest.
- Experiment with toe position: toes up to bias the hamstrings, toes pointed to bring in the calves.
- Keep the negative slow and deliberate, controlling the lever all the way to a near-straight knee.
- Set the ankle pad just above your heels, not on your calves, so the lever sits where you can drive it.
Sets & reps
For most lifters, 3 sets of 10 to 15 reps with about 75 seconds of rest is an excellent default and matches FORMA's seed programming. For hypertrophy (size), stay in the 8 to 15 rep range and chase a deep contraction with a slow negative, stopping a rep or two shy of failure. For strength, you can work slightly heavier in the 6 to 10 range, though as an isolation move the leg curl responds best to moderate loads and clean form rather than maximal weight. For muscular endurance or as a finisher, 15 to 20 reps works well. Beginners should prioritize control and full range over load; add weight only once your form stays crisp across all sets.
Frequently asked questions
What muscles does the lying leg curl work?
The lying leg curl primarily targets the hamstrings on the back of the thigh, which flex the knee to draw your heels toward your glutes. The calves, specifically the gastrocnemius, assist as secondary movers because that muscle also crosses the back of the knee. Pointing your toes changes how much the calves contribute.
Is the lying leg curl good for beginners?
Yes. It's a beginner-friendly machine exercise because the machine guides the movement path and supports your torso, so there's very little technique to coordinate. Just align your knee with the machine's pivot, keep your hips down, and curl under control. Start light and progress the weight as your form stays clean.
What's the difference between lying and seated leg curls?
Both isolate the hamstrings through knee flexion, but body position changes hip angle and stretch. The lying leg curl has your hips flat, while the seated version keeps hips bent, which puts the hamstrings under more stretch. Many lifters use both for complete development; either is a strong hamstring builder.
Why do my hips lift off the pad during leg curls?
Hips lifting usually means the weight is too heavy or you're using momentum to swing the lever up. Lower the load, consciously press your pelvis into the bench, and curl using only your knees. Keeping your hips anchored ensures the hamstrings, not your lower back, do the work and keeps the exercise safe.
How many sets and reps should I do on the lying leg curl?
A solid default is 3 sets of 10 to 15 reps with about 75 seconds of rest. For size, stay in the 8 to 15 range with a slow negative; for endurance, push toward 15 to 20 reps. As an isolation move, it rewards controlled moderate loads over heavy ego lifting.
Does pointing my toes change the lying leg curl?
Yes. Pointing your toes down (plantarflexion) lets the gastrocnemius calf muscle assist more in the curl, which can take some emphasis off the hamstrings. Pulling your toes up toward your shins takes the calves out and biases the hamstrings harder. Pick the cue that matches your goal for that set.