Seated Leg Curl vs Lying Leg Curl: Which Builds More Hamstring?

Short answer: the seated leg curl likely has the edge for hamstring growth because it loads the hamstring in a more lengthened position, and muscles trained under stretch tend to grow more. Jeff Nippard, citing a 12-week hypertrophy study, reports the seated curl produces approximately 50% more hamstring growth than the lying version. The lying curl is not useless — but the gap is real enough to act on.

What the evidence says

The core principle behind the seated-vs-lying debate is not about the machines themselves — it is about where in the hamstring's range of motion the load lands.

When you perform a lying leg curl, your hip is in a relatively neutral or slightly flexed position. The hamstring is working, but it is not at its most stretched. The seated leg curl changes this: because your hip is flexed at roughly 90 degrees while seated, the hamstring is already in a longer, more elongated position before you even start the movement. Every rep you do is pulling against resistance while the muscle is closer to its end-range length.

This matters because training a muscle in a lengthened position appears to produce more hypertrophy than training it in a shortened position — a finding that has been showing up repeatedly in recent exercise science. Jeff Nippard, ranking the seated leg curl as his #10 exercise of all time, cites a 12-week hypertrophy study reporting approximately 50% more hamstring growth from the seated curl compared to the lying version. That is a large difference for a single technical swap.

The same lengthened-position principle shows up elsewhere in Nippard's rankings, which is useful for understanding how broadly it applies. He notes that the overhead cable triceps extension produces approximately 40% more triceps growth than standard pressdowns — attributing this to May et al. — because the long head of the triceps is more stretched when the arm is raised overhead. The seated leg curl is the hamstring equivalent: same mechanism, similar magnitude of effect.

Where the experts land

Both Jeff Nippard and Eugene Teo favour the seated curl, and notably they arrive there from different directions.

Nippard's angle is growth. His ranking is built around hypertrophy evidence, and the seated curl earns its #10 spot specifically because of the size advantage that the lengthened loading position provides. If your goal is to build the back of your legs, the data he cites makes the seated curl the default choice.

Eugene Teo comes at it from the athletic and injury-resilience side. In a full lower-body training session filmed with physique champion Hattie, Teo selects the seated leg curl because it locks you in and loads the hamstring in a lengthened position that directly mimics where hamstring injuries happen — the outstretched leg position at the bottom of an RDL, or the extended position during sprinting. His reasoning: if you want hamstrings that hold up under athletic demand, you need to train them where they are most vulnerable, and the seated curl does exactly that.

Two different frameworks, one convergent answer. Teo is not citing the same 12-week study Nippard references — he is reasoning from injury mechanics and athletic training principles. The fact that they land in the same place from different angles is worth noting.

The honest caveat

The 50% figure comes from a single 12-week study. That is a strong and specific result, but it is one trial, not a body of decades-settled evidence. Treat it as a promising, actionable finding — not an iron law. The direction of the evidence (lengthened-position training produces more growth) is increasingly well-supported across multiple muscle groups; the exact magnitude for hamstrings specifically warrants more replication.

The lying leg curl is also not a waste of time. If it is the only hamstring machine your gym has, you will build hamstrings with it. If you have chronic lower-back discomfort that makes the seated position awkward, the lying curl may be the more sustainable option. Machine geometry also varies between manufacturers — if a seated curl machine at your gym does not allow a meaningful stretch at the top, you lose much of the advantage.

Individual leverages and comfort matter. The principle is clear; the implementation is yours to test.

Run your own experiment

Hamstring size is genuinely hard to eyeball week to week — the back of the leg is not easy to assess in a mirror, and short-term swelling from soreness can fool you. So do not try to evaluate this by appearance over four weeks. Evaluate it by these instead:

1. Loadable range — over 4–6 weeks on one variation, are you adding weight or reps with control? If you are progressing on seated but stalling on lying, that is signal.
2. Quality of the stretch feeling — in the seated curl, you should feel a meaningful pull on the hamstring at the top of the movement (when the leg is most extended). If you do not feel a stretch, check the machine setup — the seat back angle and pad positioning matter.
3. Recovery and soreness pattern — the lengthened-position stimulus tends to produce more muscle damage (DOMS) initially. Some early soreness from the seated curl is expected; it is not a reason to stop, but it does mean easing into the load.
4. Adherence — a variation you avoid because it is uncomfortable is worse than a variation you actually do. If the seated curl is so awkward in your gym's specific machine that you skip it, that is more important than the principle.

Run 4–6 weeks of seated curls as your primary hamstring isolation, keeping sets and load progression consistent. Then compare against how your lying curl blocks have felt in the past. The honest conclusion comes from your own log, not the mirror.

FAQ

Is the seated leg curl better than the lying leg curl? For hamstring growth, the evidence suggests yes. Jeff Nippard, citing a 12-week hypertrophy study, reports the seated curl produces approximately 50% more hamstring growth than the lying version. The mechanism is the lengthened position — the hip flexion in the seated curl places the hamstring at a longer length under load, which appears to drive more hypertrophy. The lying curl still works; the seated version appears to work more.

Why does the seated leg curl build more hamstring than the lying version? Because of hip position. In the seated curl, your hip is flexed at roughly 90 degrees, which means the hamstring is already elongated before the rep begins. Training a muscle in a more lengthened or stretched position has been shown to produce greater hypertrophy — the same principle explains why overhead cable triceps extensions outperform pressdowns for triceps growth.

Should I do both seated and lying leg curls? You do not need to, but there is no harm in it. If you only have time for one, the seated curl appears to be the better choice for growth. If your gym has both and you want variety in your hamstring work, doing seated as your primary and lying as an accessory is a reasonable approach. The important thing is that you are getting meaningful hamstring isolation with good range of motion and progressive overload — variation matters less than consistency.

Which is better for hamstring injury prevention? The seated leg curl has a specific advantage here. Eugene Teo favours it because it loads the hamstring in a lengthened, outstretched position that closely mimics the positions where hamstring strains tend to occur — the extended-leg position at the bottom of an RDL, or the driving phase in sprinting. Training the hamstring under load at that length builds resilience in the range where it is most vulnerable, which is directly relevant for anyone doing athletic work, running, or heavy hip-hinge movements.

Related reads: How Many Reps in Reserve for Hypertrophy? · Why Am I Not Gaining Muscle?

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