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Leg Curl

Also called: Hamstring curl, lying/seated leg curl

Primary muscles: Hamstrings

Joints / actions: Knee joint (tibiofemoral joint) (flexion)

Plane: sagittal

Equipment: cable-machine

What it is

Lying face-down (or seated) at a machine, bending the knees against resistance to curl a padded lever toward the buttocks.

Purpose

Isolates the hamstrings for knee flexion without involving the hip joint.

Starting position

Lie face-down on the machine with the ankles behind the padded lever, legs straight.

Step by step

  1. Curl the lever up by bending the knees, bringing the heels toward the buttocks.
  2. Pause briefly at the top without lifting the hips off the pad.
  3. Lower back down under control to full leg extension.

Breathing

Exhale as you curl the legs up; inhale as you lower.

Coaching cues

"Curl with the hamstrings, keep the hips down, control the lowering."

Common mistakes

Lifting the hips off the bench to cheat more weight up; using a fast, uncontrolled tempo; not completing the full range.

Easier regression

Reduce load, or use a single-leg version with a lighter setting for more control.

Harder progression

Increase load, or add a slow eccentric (lowering) phase for more time under tension.

Alternatives

Nordic hamstring curl (advanced, bodyweight), stability-ball leg curl.

Who may benefit

Anyone building hamstring strength as an accessory to squats/deadlifts, or targeting hamstring balance for injury-risk reduction in sport.

Who should modify or avoid it

Those with a recent hamstring strain should get clearance and use light load/range before progressing.

Why this exercise works

As a single-joint (knee-only) movement, it isolates the hamstrings' knee-flexion action, complementing hip-hinge exercises (which train hamstrings mainly through hip extension) for balanced hamstring development.

⚠ Safety note

Move through a comfortable range without forcing extra flexion; avoid jerking the weight.

Sources

“The hamstring muscles flex the leg at the knee joint.”

Anatomy and Physiology 2e — OpenStax, Rice University · Ch. 11.6 Appendicular Muscles of the Pelvic Girdle and Lower Limbs

Peer-reviewed textbook · License: CC BY-NC-SA 4.0 · Last checked 2026-07-19

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