Legs · Isolation
Lying Leg Curl
The lying leg curl is a machine isolation exercise where you lie face down and curl a padded roller towards your glutes by bending your knees. It trains the hamstrings through knee flexion, which is the function heavy hinge movements like deadlifts and Romanian deadlifts largely miss.
Also known as: Prone leg curl, Lying hamstring curl, Leg curl machine
- Muscle group
- Legs
- Movement pattern
- Isolation
- Type
- Isolation
- Equipment
- Leg curl machine
- Difficulty
- Beginner
What muscles does the lying leg curl work?
Primary movers
- Hamstrings
Assisting muscles
- Calves
- Gluteus maximus
The hamstrings have two jobs: extending the hip and flexing the knee. Most lower-body training only covers the first. Deadlifts, Romanian deadlifts and good mornings all load hip extension heavily, and none of them ask the hamstrings to bend the knee under resistance.
The lying leg curl covers that second function directly. Biceps femoris, semitendinosus and semimembranosus all cross the knee and all contract to curl the roller towards your glutes, which is why the exercise pairs so well with hinge work rather than duplicating it.
There is a detail worth knowing here. The short head of the biceps femoris crosses only the knee, not the hip, so it is essentially untrained by any hinge movement. A leg curl is one of the very few exercises that loads it at all.
Lying face down puts the hip in extension, which shortens the hamstrings at one end before the set begins. That limits how much force they can produce compared with a seated curl, where the hip is flexed and the muscle starts lengthened, worth knowing when your seated numbers look better than your lying ones.
The calves assist through gastrocnemius, which also crosses the back of the knee. Pointing your toes away recruits it more; pulling them towards your shins takes it out of the movement and shifts more of the work onto the hamstrings.
How to do the lying leg curl
Setup
- 1
Adjust the roller pad so it sits just above your heels, against your achilles rather than your calves.
- 2
Lie face down with your knees just past the edge of the bench, aligned with the machine's pivot.
- 3
Grip the handles and pull your shoulders down away from your ears.
- 4
Press your hips firmly into the pad and brace your abs.
- 5
Take the slack out of the stack so the hamstrings are loaded before the first rep.
Execution
- 1
Curl the roller towards your glutes by bending your knees, keeping the movement smooth.
- 2
Drive to the point where the hamstrings are fully contracted and hold for a beat.
- 3
Keep your hips pressed down. They should not lift off the bench at any point.
- 4
Lower over two to three seconds under full control.
- 5
Stop just short of your legs straightening completely so tension stays on the muscle.
- 6
Keep your toes pulled towards your shins throughout to keep the calves out of it.
Common lying leg curl mistakes
Lifting the hips off the pad
Arching the lower back and raising the hips to help the roller up. This turns the movement into a partial hip extension, takes load off the hamstrings and compresses the lumbar spine.
The fix: Reduce the weight and consciously press your hips into the bench. If your hips lift on the last two reps, the set ended two reps ago.
Cramping from going too heavy too quickly
Hamstrings cramp more readily than almost any other muscle, particularly when jumping straight into heavy leg curls without warming up.
The fix: Do a light set of 15–20 reps before your working sets and build load gradually. Cramping is usually a warm-up problem rather than a hydration problem.
Bouncing out of the bottom
Letting the roller drop and using the rebound of the weight stack to start the next rep. It removes the hardest, most productive part of the range.
The fix: Control the descent over two to three seconds and start each rep from a dead-stop under tension, without letting the stack rest.
Misplacing the roller pad
Setting the pad on the calves rather than just above the heels. It shortens the lever, is genuinely uncomfortable, and lets you move more weight than the hamstrings can actually handle.
The fix: Position the pad against the back of your ankles, just above the heel. Reset it each session. The last person will have changed it.
How many sets and reps?
| Goal | Sets | Reps | Load | Rest |
|---|---|---|---|---|
| Hypertrophy | 3–4 | 8–15 | Moderate, 0–2 RIR | 60–90 s |
| Injury prevention | 3 | 10–12 | Slow eccentric emphasis | 90 s |
| Metabolic finisher | 2–3 | 15–20 | Light | 45–60 s |
Leg curls are worth including in almost every lower-body programme, because knee flexion is the hamstring function that hinge movements leave untrained, and hamstring strength imbalances are strongly associated with hamstring strains in sprinting and field sports. Two to four sets once or twice a week is sufficient. Emphasising a slow lowering phase matters here: eccentric hamstring work has the best evidence behind it for reducing strain risk.
Running the lying leg curl in your next block? Hercules logs every set, shows last session's numbers before you lift, and suggests when to add weight.
Get it on Google PlayLying Leg Curl variations and alternatives
Seated Leg Curl
AlternativeFlexing the hip lengthens the hamstrings before the set begins, which loads them in a stretched position and tends to produce more growth than the lying version.
Single-Leg Lying Curl
HarderCurling one leg at a time exposes strength differences between sides and stops the stronger leg quietly compensating.
Nordic Hamstring Curl
HarderA bodyweight knee-flexion movement with an extremely demanding eccentric. It has the strongest evidence of any exercise for reducing hamstring strain rates.
Romanian Deadlift
AlternativeTrains the hamstrings through hip extension rather than knee flexion. Complementary. Most programmes should contain both, not one or the other.
Stability Ball Leg Curl
EasierRequires no machine and adds a stability demand. A practical home substitute, though the load ceiling is low.
Frequently asked questions
Are lying or seated leg curls better?
Seated curls have a slight edge for hypertrophy. Sitting places the hip in flexion, so the hamstrings begin each rep in a lengthened position, and training a muscle at longer lengths generally produces more growth. Lying curls remain effective and hit the same muscles, if your gym has both, using both is a reasonable approach.
Do I need leg curls if I already deadlift?
Yes, if complete hamstring development matters to you. Deadlifts and Romanian deadlifts train hip extension but involve almost no knee flexion, and the short head of the biceps femoris only crosses the knee, so it goes essentially untrained by hinging. Leg curls fill that gap.
Why do my hamstrings cramp during leg curls?
Usually insufficient warm-up combined with jumping to a heavy load. Hamstrings are particularly prone to cramping because they are often relatively weak in knee flexion compared with their hip extension strength. A light set of 15–20 reps beforehand and a more gradual load progression fixes it for most people.
Should I point my toes on leg curls?
Pull your toes towards your shins. Pointing them away brings the gastrocnemius into the movement, since it crosses the back of the knee too. That lets the calves assist and takes work away from the hamstrings you are trying to train.
How many leg curls should I do?
Three to four sets of 8–15 reps, once or twice a week, is enough alongside your hinge work. Prioritise a controlled two to three second lowering phase over adding weight, the eccentric portion carries the most benefit for both growth and injury resistance.
Hercules tracks every lying leg curl you log, shows you last session's numbers before you lift, and flags when your progress stalls.
Get it on Google Play