How to Seated leg curl: Form, Muscles and Mistakes

What it is

A machine curl in which you sit with your hips bent and curl the pad down with your heels. The flexed hip position stretches the hamstrings before the movement begins, and research comparing it with the lying version has found greater growth in this position.

Muscles worked

Primary: Hamstrings. Secondary: Calves.

How to perform it

Set the back pad so your knees line up with the machine's pivot, and the lap pad snug over your thighs.
Place your heels on the roller with your legs almost straight, and hold the handles.
Curl your heels down and under as far as the machine allows, keeping your hips pinned to the seat.
Return under control to a full stretch without letting the weight stack rest between reps.

Common form faults

Hips lifting off the seat to help. Tighten the lap pad and reduce the weight; the hips must stay down for the hamstrings to work at the intended length.
Letting the weight drop back fast. Control the return — the lengthened portion is where most of this exercise's value lies.
Pivot misaligned with the knee. Adjust the seat before your first rep; a misaligned pivot puts shear through the knee and reduces the range you can use.

Programming

A hamstring accessory, typically in moderate to higher reps. Worth including even if you deadlift, since knee-flexion work trains the hamstrings in a way hip hinges do not.

Frequently asked questions

Seated or lying leg curl?

Seated, if you have to choose. The flexed-hip position puts the hamstrings under load at a longer length, and direct comparisons have found greater growth from it.

Do I need leg curls if I do Romanian deadlifts?

Ideally yes. Hinges train the hamstrings at the hip, curls train them at the knee, and the two produce different regional growth. Most complete programmes include both.