How to do the leg curl

Squats, lunges and leg presses do a lot for your quads and glutes, and surprisingly little for your hamstrings. The hamstrings have two jobs, extending the hip and bending the knee, and the leg curl is the simplest way to train the knee part. Pair it with a hip hinge like the Romanian deadlift and you've covered both. It's a low-skill machine, so it's a good exercise to push hard near the end of a session.

How to do a leg curl

These steps are for the lying leg curl. The seated version works the same way; the differences are below.

1. Line your knees up with the machine's pivot. Lie face down with your kneecaps just off the edge of the bench, so your knee joint sits level with the axle the arm rotates around.
2. Set the pad just above your ankles. It should rest on the back of your lower calves, above the heel, not on your Achilles or halfway up your calf.
3. Grip the handles and press your hips into the bench. Your hips stay down for the whole set.
4. Curl your heels toward your glutes. Stop when your knees are bent past 90 degrees and the pad is close to your glutes, or as far as you can go without your hips lifting. Squeeze your hamstrings at the top for a moment.
5. Lower over 2 to 3 seconds. Stop just before your legs are fully straight so the weight stack doesn't touch down between reps.

You should feel it in the back of your thighs, mostly in the middle and toward the knee. Cramping in your hamstrings on the first few sets is common and usually eases as you get used to the exercise. If you feel it in your lower back, your hips are lifting.

Cues that help

"Heels to your glutes." Gets you to finish the rep instead of stopping halfway.

"Hips heavy." Keeps your pelvis pinned to the pad. If that doesn't land, try pulling yourself into the bench with the handles.

"Slow on the way down." The lowering is where most people waste the rep by letting the stack drop.

Your foot position matters a little. Pulling your toes toward your shins usually lets you lift more because your calves chip in; pointing them takes the calves out and makes the hamstrings work harder. Either is fine. Pick one and keep it the same so your numbers stay comparable.

Common mistakes

Lifting your hips off the pad. As the set gets hard, your hips rise and your lower back arches to help finish the curl. It shortens the range for your hamstrings and loads your back. The usual cause is too much weight. Drop a plate or two and keep your hips down, even if that means fewer reps.

Swinging the weight up. A fast kick at the bottom lets momentum carry the pad halfway up, so the hamstrings only work in the top half. Pause for a moment at the bottom of each rep, then curl without jerking.

Cutting the range short. Stopping at 45 degrees or never letting the legs get close to straight gives you half the exercise. Use a weight you can move from nearly straight legs to a full squeeze at the top. If your gym's machine has a range-limiting pin, check it's not set to cut you short.

Lying or seated?

Use the seated leg curl if your gym has both. In a 12-week study by Maeo and colleagues, 20 untrained adults trained one leg on a seated curl and the other on a lying curl. The seated leg grew noticeably more, most likely because sitting bends your hips and trains the hamstrings in a more stretched position. It's one study in beginners, but it fits with other research on training muscles at long lengths, and there's no downside to choosing seated.

On a seated curl, set the backrest so your knees line up with the pivot, lock the thigh pad down firmly just above your knees, and put the lower pad just above your heels. Sit tall and hold the handles; the same cues and mistakes apply, except that your thighs rise off the seat instead of your hips.

Sets, reps and how much weight to use

Leg curls respond well to moderate and high reps. For most people, 2 to 4 sets of 8 to 15 after your main leg lifts is about right. Pick a weight you could do 1 or 2 more reps with. Because it's a simple machine, it's also a safe exercise to take to failure on your last set. Rest 60 to 90 seconds.

Here's roughly what people use for working sets:

Leg Curl working weights by bodyweight and experience

Bodyweight	beginner	intermediate	advanced
130 lb (59 kg)	25 lb (11 kg)	50 lb (23 kg)	80 lb (36 kg)
160 lb (73 kg)	30 lb (14 kg)	65 lb (29 kg)	95 lb (43 kg)
190 lb (86 kg)	40 lb (18 kg)	75 lb (34 kg)	115 lb (52 kg)
220 lb (100 kg)	45 lb (20 kg)	90 lb (41 kg)	130 lb (59 kg)
250 lb (113 kg)	50 lb (23 kg)	100 lb (45 kg)	150 lb (68 kg)

Treat these loosely. Leg curl machines vary more than most, and the same number on the stack can feel very different from gym to gym. Compare yourself with your own numbers on the same machine, and add weight once you hit the top of your rep range on every set.

Variations and alternatives

• Seated leg curl: our first choice if you have access to one.
• Single-leg curl: the same machine one leg at a time. Useful if one hamstring is noticeably weaker.
• Standing cable or machine curl: one leg at a time, standing. Good if your gym has no lying or seated machine.
• Nordic curl: kneel with your ankles anchored and lower your body forward slowly. Very hard; start with just the lowering, using your hands to catch yourself.
• Stability ball or slider curl: a no-machine option for home. Lie on your back, heels on the ball, and curl it toward you with your hips up.
• Romanian deadlift: trains the hamstrings at the hip instead of the knee. Do both if you can.

Leg curl questions

Do I need leg curls if I do deadlifts?

We'd still do them. Deadlifts and Romanian deadlifts train the hamstrings through the hip, but they barely bend the knee, which is the other half of what the hamstrings do.

Why do my hamstrings cramp during leg curls?

It's common, especially the first few times or when you point your toes. Try pulling your toes up toward your shins, use a slightly lighter weight, and do a light warm-up set first. It usually stops within a few sessions.