Leg curl: seated or lying, the setup, and curls without a machine

The leg curl is a machine where you bend your knees against a padded lever, seated, lying face down or standing on one leg. It trains the hamstrings, the muscles on the back of the thigh, through the job a hinge like the Romanian deadlift doesn't do: bending the knee. Most of the hamstring muscles cross both the hip and the knee, so a hinge and a curl train them from two ends.

This page covers which version to choose and why, the setup, the rep and its tempo, whether foot position matters, curls at home without a machine, and the faults. The session around it is on the leg day workout, and the hinge is on the Romanian deadlift.

Seated vs lying leg curl

This one has a direct answer from a training trial. In a 12-week trial, 20 young adults who hadn't done any systematic lifting in the past year trained one leg on a seated leg curl and the other on a lying one, five sets of 10 twice a week. The seated leg's hamstrings grew more, 14% against 9%.¹ Sitting bends the hip, which lengthens the hamstring muscles that cross it, and the authors suggest that training them at longer lengths is why. The one hamstring muscle that crosses only the knee grew about the same either way.

So use the seated curl when you have the choice. The lying curl still worked: 9% over 12 weeks is real growth, so it's a fine choice when it's the machine your gym has. A standing one-leg curl puts the hip about where the lying curl does.

What it trains, next to the hinge

• The curl reaches parts a hinge doesn't. In 15 trained women, activity in the upper and lower biceps femoris, one of the hamstrings, was higher in the leg curl, the Nordic curl and a kickback than in the Romanian deadlift, the step-up or a hip extension. The glutes did the least in the leg curl.²
• Another study leans the other way. In 12 weight-trained men, hamstring activity was highest in the Romanian deadlift and the glute-ham raise, ahead of the leg curl and the good morning.³

Two small activity studies, in different groups, with different exercises. The plain reading is that neither replaces the other: a hinge and a curl on the same week cover the hamstrings from the hip and from the knee.

How to set up the leg curl

Seated:

1. Move the backrest until the bend of your knee lines up with the machine's pivot.
2. Set the lower pad on the back of your lower legs, just above the heels.
3. Lower the thigh pad until it sits snug on your thighs just above the knees, so your hips can't lift.
4. Sit back against the backrest and hold the handles.

Lying: lie face down with your knees just past the edge of the bench and the pad just above your heels. Hold the handles and keep your hips pressed into the bench.

The rep and the tempo

1. Curl your heels down and back, seated, or up toward your glutes, lying, as far as the machine allows.
2. Squeeze for a second at the end of the curl.
3. Return in about two or three seconds until your knees are nearly straight. That's where the hamstrings are longest, so don't stop short of it.

A controlled return is about keeping the weight under control, not about adding growth: how long a rep lasts made little difference to muscle growth across a wide range of speeds. (Time under tension covers the evidence.)

Feet pointed or pulled up? In one study of the lying leg curl, foot position made no difference to hamstring activity during the curl. In the same study's training part, trained adults curled for ten weeks with one foot pointed and the other pulled up, and strength gains and growth of the biceps femoris didn't differ between the legs.⁴ Use whichever lets you curl hardest without a cramp in the calf.

Leg curls at home, without a machine

• Slider or towel leg curl. Lie on your back with your heels on sliders or a towel on a smooth floor, lift your hips into a bridge, and pull your heels toward you, then slide them back out without letting your hips drop. Do one leg at a time when two gets easy.
• Band leg curl. Lie face down with a band around your ankles anchored low in front of you, and curl as on the lying machine.
• Nordic curl. Kneel with your heels held under something heavy and lower your body forward as slowly as you can, catching yourself with your hands. In the 15 trained women above, it produced the highest biceps femoris activity of the six exercises.² In 32 young adults who trained twice a week for six weeks, a Nordic curl program and an RDL program that stressed the lowering phase both grew the hamstrings by about 10%, with no difference between them.⁵ It's hard: start with the lowering only.

No study of the slider or band curl was found. A review of eight studies found bands and tubing produced similar strength gains to machines and dumbbells for the lower body,⁶ so a band is a fair stand-in for the machine; the slider curl is the same knee bend with your body weight.

The common faults, and a fix for each

• Hips lifting. On the lying curl the hips rise to help the last reps. On the seated curl, a loose thigh pad does the same. Press the hips down, or tighten the pad.
• Knees out of line with the pivot. The pad slides along your calves during the rep. Move the backrest or your body until it doesn't.
• Half reps. Stopping short of a straight knee cuts off the longest position. Return all the way.
• Jerking the weight. If the stack slams, it's too heavy. Curl smoothly, return slowly.
• Curling through pain. Sharp pain is not soreness. Stop, and see a doctor or a physical therapist.

Sets, reps and where it goes

• Three sets of 10 to 15, after the squat or leg press and the hinge, as on the leg day workout, a rep or two from failure. (How to judge reps left.) The American College of Sports Medicine's 2026 position stand advises at least two sets per exercise.⁷
• Twice a week if you train legs twice: one day with the hinge, one with the curl, or both on both.
• Pair it with the leg extension, front and back of the thigh, often on machines side by side.
• After a machine squat? The hack squat trains mainly the front of the thigh, so the curl is the back-of-thigh half of that day.

If you'd rather not plan it alone

A leg curl is easy to learn; balancing it against your hinges so the hamstrings get enough work from both ends is the part a page can't do. Coaching is the version where your workouts are built around the days you actually have, and a weekly call looks at the week you just had and rebuilds the next one. Coaching to build muscle explains how that works, and here's how to apply. Otherwise: find the seated leg curl, line your knees up with the pivot, and do three sets of 12.