Leg curl: seated versus lying, and why it matters
Use the seated leg curl if you have the choice. With the hip flexed, the hamstrings are trained at a longer muscle length, and direct comparisons show greater growth than the lying version. Control the eccentric and use a full range.
Why the hip position matters
The hamstrings cross two joints: they extend the hip and flex the knee. A leg curl trains knee flexion — but how much the muscle is stretched during that depends on where your hip is.
- Seated leg curl: hip flexed around 90°, so the hamstrings start at a longer length and stay longer throughout.
- Lying leg curl: hip extended, so the hamstrings work at a shorter length.
This matters because training at longer muscle lengths tends to produce more hypertrophy, and it has been tested directly on this exact comparison: seated leg curls produced greater hamstring growth than lying leg curls over a training period, in a study using matched training.
| Variation | Hip position | Emphasis | Note |
|---|---|---|---|
| Seated leg curl | Hips flexed ~90° | Hamstrings at longer length | Generally produces more growth than lying, in direct comparisons. |
| Lying leg curl | Hips extended | Hamstrings at shorter length | Still effective; different position. |
| Standing single-leg curl | Hips extended | One side at a time | Good for side differences. |
| Nordic curl | Hips extended, bodyweight | Very high eccentric demand | Excellent, hard, well evidenced for hamstring injury reduction. |
| Glute-ham raise | Hips extended | Hamstrings plus glutes | Requires a specific bench. |
This is unusual. Most machine-versus-machine choices are close to irrelevant, and this one is not. If your gym has both, use the seated version as your default.
Technique
- Adjust the seat so your knees align with the machine's pivot point. This is the setting most people never touch and it changes the exercise.
- Pad just above the heels, on the lower calf, not on the Achilles.
- Thigh pad snug so your hips do not lift.
- Back against the seat, hips stable.
- Curl through a full range, bringing the heels as close to the glutes as the machine allows.
- Pause briefly at the top.
- Lower slowly — two to three seconds. The eccentric is where most of the hamstring benefit lives.
- Straighten fully at the bottom without letting the weight crash down.
Point or flex the toes? Pointing the toes (plantarflexion) reduces the calf's contribution to knee flexion, in principle putting more work on the hamstrings. The effect is small — pick whichever feels better and stay consistent.
Faults and fixes
- Knees not aligned with the pivot. Adjust the seat. This is the most commonly ignored setting in the gym.
- Hips lifting off the seat. Too much weight, or the thigh pad is loose.
- Partial range. Curl as far as the machine allows and straighten fully.
- Dropping the weight on the way down. The eccentric is the valuable part.
- Pad on the Achilles. Painful. Move it to the lower calf.
- Jerking with the whole body. Reduce the weight.
Nordic curls, which deserve a mention
The Nordic hamstring curl — kneeling with the ankles held, lowering the torso forward under control — has better evidence behind it than almost any other single exercise, specifically for reducing hamstring injury rates in sport.
- Very high eccentric demand. Most people cannot control the full range initially.
- Start with assistance: push off the floor with your hands, use a band, or only lower part-way.
- Low volume is enough. Two or three sets of three to six reps, twice a week.
- Expect real soreness for the first few weeks.
- Needs a partner or a fixed anchor for the ankles — a loaded barbell or a Nordic bench.
If you play a sport involving sprinting, this is one of the highest-value exercises available to you.
Programming
- Hypertrophy: 3 sets of 8–15, controlled eccentric.
- Twice a week.
- Pair with a hip-extension hamstring exercise. Leg curls train the knee-flexion function; RDLs train the hip-extension function. Both are needed for complete hamstring development — see Romanian deadlift.
- Higher reps work well. The hamstrings tolerate 12–20 rep sets comfortably.
- Train them directly. Squats and leg presses do very little for the hamstrings, which is why they are commonly underdeveloped.
Common questions
Seated or lying leg curl?
Seated, if available. The hip-flexed position trains the hamstrings at longer lengths and produced more growth in a direct comparison.
Should I point or flex my toes?
Pointing may slightly favour the hamstrings. The difference is small — be consistent.
Do I need leg curls if I do RDLs?
Yes. They train different hamstring functions.
Why are my hamstrings so weak compared with my quads?
Because most programmes train the quads with every squat and press, and the hamstrings only when you do something specific.
Are Nordic curls worth it?
Very much so if you sprint or play field sports. Start assisted.
How heavy should I go?
Heavy enough for 8–15 hard reps with a controlled lower and no hip lift.
Why do I cramp during leg curls?
Common in the hamstrings at end range. Reduce the weight and range slightly, and build up.
The practical version
- Use the seated version — the hip-flexed position produced more growth in direct comparison.
- Align your knees with the machine's pivot; adjust the seat.
- Full range, brief pause at the top, two-to-three second lower.
- Pair with RDLs — leg curls train knee flexion, RDLs train hip extension.
- Nordic curls have strong evidence for reducing hamstring injuries in sport.
- Squats and leg presses do very little for the hamstrings; train them directly.
Key takeaways
- Seated leg curls produced greater hamstring growth than lying curls in a direct comparison.
- The hip-flexed position trains the hamstrings at a longer muscle length.
- Align your knees with the machine's pivot — the most commonly ignored setting.
- Control the eccentric over two to three seconds; that is where the benefit lives.
- Pair leg curls with RDLs: knee-flexion and hip-extension functions are both needed.
- Nordic curls have unusually strong evidence for reducing hamstring injury in sport.
Related reading
General information, not medical or individualised advice. Speak to a doctor before starting a new programme, especially if you have a medical condition, are pregnant, or are returning from injury. If you train with a coach, their guidance takes precedence.
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