Leg Curls
The machine leg curl flexes the knee against a padded lever, isolating the hamstrings in the one job compound lifts rarely train directly — bending the knee under load. It belongs in nearly every lower-body program, from physique work to hamstring-strain prevention. Coached by Maddy (NASM-CPT) — these are the exact form cues he gives on every client's first week.
Muscles worked
Sets & reps by goal
| Goal | Sets × Reps | Rest |
|---|---|---|
| Strength | 4 × 5–6 | 2 min |
| Muscle | 3–4 × 9–12 | 60–90 s |
| Endurance | 3 × 18–25 | 45–60 s |
Rep ranges per Helms 2014 · Schoenfeld 2016.
Level — Beginner
Beginner — machine-guided and safe to take close to failure once form is set.
Proper form — 5 cues
- Adjust the machine so the knee joint lines up with the machine's pivot point.
- Set the pad just above the heels, on the lower calf — not on the Achilles.
- Curl the heels toward the glutes in a smooth arc, hips staying glued to the pad or bench.
- Squeeze hard for a beat at full flexion.
- Lower on a slow three-count to a full stretch without the plates slamming.
Breathing: Exhale as the heels curl in, inhale through the slow lowering.
The 3 mistakes Maddy corrects most
Common questions
Do I need leg curls if I already deadlift?
Deadlifts and their variations train the hamstrings as hip extenders, but the hamstrings also cross the knee — and knee flexion is a separate job that hinging barely loads. Curls fill that gap directly. For complete hamstring development and resilience, most programs benefit from training both functions.
Lying, seated, or standing leg curl — does it matter?
Seated curls hold the hips flexed, which lengthens the hamstrings and generally allows a stronger stretch-position stimulus; lying curls are the classic default; standing single-leg versions add a balance and asymmetry check. Use whichever your gym offers — and if there is a choice, the seated version is a strong first pick.
Why do my calves cramp during leg curls?
The calves' gastrocnemius also crosses the knee, and it tries to help when the hamstrings are undertrained or the toes are pulled hard toward the shins. Try curling with the ankles relaxed or toes pointed slightly, lighten the load, and build up gradually — the cramping usually fades within weeks.
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