Exercise library
Leg Curl
Why knee flexion trains hamstrings that RDLs miss, seated versus lying compared, and the hip position that changes which part you load.
How to do the leg curl
- 01Set the machine so the pad sits just above your heels and the pivot lines up with your knee joint.
- 02Lie face down or sit back, depending on the machine, and hold the handles.
- 03Keep your hips pressed into the pad — do not let them lift as you curl.
- 04Curl your heels toward your glutes under control, pausing briefly at the top.
- 05Lower slowly to a full stretch. The lowering should take about twice as long as the lift.
Coaching cues
- Point your toes away to reduce calf involvement, or pull them toward you to increase it.
- Hips stay down. Lifting them is how you shorten the range without noticing.
- Control the negative — that is where hamstring injuries are prevented.
Common mistakes
FaultHips rising off the pad
FixToo much weight. The lift becomes a hip movement rather than a knee one, and the range collapses.
FaultDropping the weight on the way down
FixThe lowering phase is the most protective part of the exercise for hamstring health. Take three seconds over it.
FaultPad set on the calf rather than above the heel
FixToo high and the leverage is wrong and the shin gets sore. Set it just above the heel.
FaultOnly ever training hip hinges
FixThat is the real error. Hinges and curls train different hamstring functions and you want both.
The leg curl gets dismissed as a machine exercise for people who will not do proper lifts. That dismissal costs a genuine chunk of hamstring development.
Two jobs, two exercises
The hamstrings cross two joints. They extend the hip, and they flex the knee.
Hip hinges — Romanian deadlifts, deadlifts, good mornings — train the first job and train it well. They do very little for the second, and the short head of the biceps femoris only crosses the knee, so it gets almost nothing from any amount of hinging.
If your hamstring training is entirely hinges, you have trained one of the two functions. The curl is not an accessory to the RDL; it is the other half.
Seated has the edge
Seated leg curls keep the hip flexed, which puts the hamstrings at a longer starting length than the lying version where the hip is extended.
Training a muscle at longer lengths appears to produce more growth for the same effort, and the comparisons between seated and lying curls line up with that. If your gym has both and you only have time for one, take the seated machine.
Own the lowering
The most valuable part of this exercise is the eccentric — the controlled lowering back to straight.
Eccentric hamstring training has good supporting evidence for reducing hamstring strain risk, which matters to anyone who sprints, plays field sport, or would like to keep doing either. Three seconds down on every rep costs nothing and is the difference between a machine exercise and a genuinely useful one.
Set the machine properly
The pad belongs just above your heels, not on your calves, and the machine’s pivot should line up roughly with your knee joint.
Get that wrong and the leverage is off, the shin gets sore, and the range shortens. It takes ten seconds to adjust and most people never touch it.
Common questions
Do I need leg curls if I do Romanian deadlifts?
Yes, if you want complete hamstring development. The hamstrings both extend the hip and flex the knee. RDLs train the first; only a curl trains the second. The short head of the biceps femoris crosses the knee only and gets almost nothing from hinging.
Seated or lying leg curl?
Seated curls hold the hip flexed, which puts the hamstrings at a longer starting length — and training at long muscle lengths appears to produce more growth. Lying curls have the hip extended. If you can only do one, seated has the edge.
Should I point or flex my toes?
Pointing the toes away takes the calves out of it and puts more work on the hamstrings, which is usually what you want. Pulling the toes toward you brings in the gastrocnemius, which also crosses the knee.
How heavy should leg curls be?
Light enough that your hips stay flat and the lowering stays controlled. Sets of eight to fifteen suit the movement. Loading it so heavily that you snap the weight up and drop it back wastes the most useful part of the exercise.
Do leg curls help prevent hamstring injuries?
Eccentric hamstring work has good evidence behind it for reducing hamstring strain risk in sport, and a slow-lowered leg curl is one accessible way to do it. The Nordic hamstring curl has the strongest evidence specifically, but it is considerably harder.
Swap it out
Same training effect, different demand on the joints.