Isolation — lower body

Leg Curl

Machine

The leg curl isolates the hamstrings and covers what deadlifts and Romanian deadlifts miss. It matters for balanced leg development and for injury prevention.

Hamstrings do two jobs — bending the knee and extending the hip — and Romanian deadlifts only train the second. The leg curl is the knee-flexion half, and skipping it leaves a meaningful part of the muscle undertrained. That matters beyond appearance: hamstring strength imbalances are strongly associated with knee and hamstring injuries.

Technique

1. 1Lie flat with your knees just past the edge of the pad
2. 2Curl up as far as you can — ideally touching your heels to your glutes
3. 3Hold for 1 second at the top and lower slowly (3 sec eccentric)
4. 4Avoid lifting your hips to help the movement
5. 5Point your toes slightly down (plantarflexion) for more recruitment

Common mistakes

• Lifting the hips off the pad to gain leverage

  Fix: Press the hips down and hold the handles. If the hips rise, reduce the weight.

• Cutting the range short at both ends

  Fix: Curl until the heels are close to the glutes and return until the legs are nearly straight. Partial curls are the norm and a waste.

• Letting the weight drop back down

  Fix: Three seconds on the lowering phase. Hamstrings respond particularly well to eccentric work — this is where the injury protection comes from.

• Training only lying or only seated

  Fix: The seated curl works the hamstrings in a stretched hip position, the lying curl in a neutral one. They produce measurably different growth, so rotate or do both.

Sets and reps

How to progress

10–15 reps with a deliberate three-second lowering. Add weight only when the full range and the tempo hold. If you can do lying curls comfortably, add Nordic curls once a week — start with a very small range of motion, because the soreness is significant.

Variations

• Seated leg curl

  Hip flexed, hamstrings stretched. Research favours it slightly over the lying version for growth.

• Nordic curl

  Bodyweight eccentric with the feet anchored. Extremely effective, and one of the best-evidenced hamstring injury-prevention exercises.

• Single-leg curl

  Corrects imbalance, which matters more here than almost anywhere else.

Frequently asked questions