Leg curl
Muscles worked : Hamstrings · Calves
How to do it
- Set the machine so the roller rests on the lower calves, just above the heels.
- Get into position with the hips flat against the support, legs straight without locking the knees.
- Bend the knees to draw the heels toward the glutes, under control.
- Lower slowly back to extension, without letting the load drop.
Common mistakes
- Hips lifting to help the curl: the movement leaves the hamstrings.
- An unbraked descent, with the load falling on its own.
- A badly placed roller, too high on the calf, which gets in the way instead of loading.
Where you should feel it
A clear contraction at the back of the thigh, from the knee toward the glute. The lower back should feel nothing: if it does, the hips have lifted.
Range of motion
Curl as far as the machine allows without the hips moving, and lower to full extension but without locking. Full range matters more than load on this movement.
Tempo and breathing
One to two seconds to curl, two to three braking on the way down. Exhale curling.
What works, precisely
The hamstrings flex the knee: that is their primary action, and precisely the one no bodyweight exercise in the library loads directly. The gastrocnemius, which also crosses the knee, assists.
Movement mechanics
Open-chain knee flexion with the hip fixed, on a guided path. It is the exact complement of the Romanian deadlift, which loads the same muscles but in hip extension with the knee near-fixed.
Benefits
- Fills the one glaring gap in the library: no exercise loaded the hamstrings in knee flexion.
- Balances the thigh work, which is heavily dominated by the quadriceps (squats, lunges, leg press).
- Guided path and adjustable load, so progress is measurable.
Adapt and progress
- Easier : Reduce the load, or shorten the range by curling a little less far.
- Harder : Increase the load, slow the descent to four seconds, or pause for a second in the flexed position.
- Move on when : When three sets of twelve go by with the hips never lifting, increase the load.
Precautions
A cramp at the back of the thigh is common on this movement: reduce the load and extend the warm-up rather than pushing on.