Seated vs Lying Leg Curl: Which Builds More Hamstring?

If your goal is hamstring size, the seated leg curl has the better evidence. In the one trial that trained both versions head to head, the seated curl grew the whole hamstring group by 14% over 12 weeks, against 9% for the lying (prone) curl. The lying curl still worked. It just worked less.

That is one small study in untrained adults, so it is a reason to prefer the seated machine, not a reason to avoid the lying one. Below we go through what the trial measured, why muscle length is the likely explanation, how other hamstring exercises fit in, and how to program and log the curl so your numbers stay comparable.

Is the seated leg curl better than the lying leg curl for hamstrings?

On the evidence we found, yes, for hamstring size. Maeo and colleagues (2021, Medicine & Science in Sports & Exercise) is the direct comparison, and its result favoured the seated curl. We did not find a second trial that repeated it, which is the main reason to hold the conclusion loosely.

The practical gap is modest. Nine percent growth in 12 weeks is a real result, and nothing in the trial suggests the lying curl is a poor choice. If your gym only has a lying machine, use it.

What did the Maeo trial find?

The trial used a within-person design. Twenty healthy adults trained one leg with a seated curl and the other with a prone curl. Both legs did 5 sets of 10 repetitions at 70% of their one-repetition maximum, twice a week, for 12 weeks. Muscle volume was measured with MRI before and after.

The three muscles that cross both joints are the semitendinosus, the semimembranosus and the long head of the biceps femoris. They grew more with the seated curl. The short head of the biceps femoris, which only crosses the knee, grew about equally.

The authors concluded that hamstring size can be increased more effectively by seated than prone leg curl training, which suggests that training at long muscle lengths promotes hypertrophy.

Why would the seated version grow more?

The likely reason is the position of the hip. In the seated curl your hips are bent, which stretches the hamstrings across the hip before the knee even starts to flex. In the prone curl your hips are extended, so the same muscles start shorter and are working at shorter lengths throughout the lift.

The pattern in the results fits that explanation. The muscles that cross the hip, and so are affected by hip position, showed the gap. The muscle that does not cross the hip showed none. This is the authors' interpretation of the data rather than something the trial isolated directly, but it is a tidy fit.

A 2026 modelling paper points the same way for knee-flexion exercises. Morin and colleagues (Medicine & Science in Sports & Exercise) used EMG-informed modelling to estimate how each hamstring muscle's length and force differed across exercises. Differences in modelled muscle length, and to a lesser extent force, explained which hamstring muscle was damaged or grew after knee-flexion work. That is a modelling approach with its own assumptions, not a second head-to-head curl trial.

The same paper is a useful warning against reading too much into one exercise. Hypertrophy was concentrated in the semitendinosus after the Nordic hamstring exercise (+24.4%) and in the semimembranosus after the stiff-leg deadlift (+11.2%). Different exercises favour different hamstring muscles, and for the stiff-leg deadlift, length did not explain the pattern.

If lengthened-position training interests you more broadly, our guide to full range of motion vs partial reps covers the wider question.

Did the two curls differ for muscle damage?

No. The second part of the Maeo study tested susceptibility to muscle damage. Participants did a hard eccentric-only leg curl session, and the researchers measured MRI signal (T2) and strength at 24, 48 and 72 hours. Legs that had trained, whether seated or prone, showed far less damage than untrained control legs, for example +4% and +6% T2 in the semitendinosus against +52% in controls at 72 hours.

Seated and prone legs did not differ significantly at any time point. So the case for the seated curl rests on growth. Neither version appears to protect you better from soreness after a hard session.

Where do Romanian deadlifts and Nordic curls fit?

They are alternatives and partners, not replacements for the comparison above. Crawford and colleagues (2025, Medicine & Science in Sports & Exercise) randomised 32 healthy people to six weeks of either an eccentrically biased Romanian deadlift or the Nordic hamstring exercise, twice a week. Changes in fascicle length, pennation angle and hamstring cross-sectional area did not differ between groups, and cross-sectional area rose about 10% in both.

That trial did not include a curl, so it cannot rank the curl against either lift. What it does show is that a hip hinge and a knee-dominant eccentric exercise can both grow hamstrings. Our guide to the Romanian deadlift vs conventional deadlift covers the hinge side.

A 2026 systematic review in Sports Health (Arin-Bal et al.) pooled 14 randomised trials with 382 participants and reported that evidence for changes in muscle volume and cross-sectional area was heterogeneous across exercise types and imaging methods. It was mainly a review of eccentric and hamstring-injury research, so we use it only to say that the wider evidence is mixed and that no single exercise has been proven the best.

How should you program leg curls?

Everything below is our reasoning from the evidence above, not a protocol any of the trials tested. The only numbers taken from the trials are the 5 sets of 10 at 70% of 1RM that Maeo used.

1. Pick the machine by availability. Seated if you have it. If you only have a lying curl, you lose a little in the three hip-crossing muscles, but you keep the stimulus.
2. Pair it with a hip hinge. A curl works the knee-flexion function and a Romanian deadlift works the hip-extension function. The trials above suggest both grow hamstrings.
3. Train hard but not blindly. Stopping about one to three reps short of failure keeps the work demanding while leaving room to repeat it next week. Our RPE vs RIR guide explains how to judge that.
4. Use the full range and control the lowering. Take the muscle through the whole movement. Stretch is the mechanism the seated curl appears to exploit, so cutting the range short wastes it.
5. Progress with double progression. Choose a range such as 8 to 12 reps, add reps until every set reaches the top, then add load. Our double progression guide walks through it.
6. Count the sets. Curls and hinges both hit the hamstrings, so they share a weekly volume budget. A common starting point is two to four hard curl sets per session, but see how many sets per muscle group before piling on more.

Who should pick which curl?

• You have a seated machine: use it as your default curl.
• You only have a lying machine: use it, and make sure you are also hinging, since the hinge trains the hamstrings at long lengths too.
• Your knees or hips dislike one position: pick the one you can do pain-free and progress. A variation you stop doing grows nothing. This is our judgement, not a trial finding.
• You want to rotate: alternating blocks is reasonable, provided you log them as separate lifts.

The outcome that matters most is a curl you can repeat and progress for months.

How do you track seated and lying leg curls?

Log them as separate exercises. The two machines have different pads, levers and seat settings, so the weight stacks are not comparable. A 45 kg seated curl and a 45 kg lying curl are different loads on the muscle.

IronLedger records weight, reps, RPE or RIR and free-text notes on every set, and it tracks personal records and estimated one-rep max (Epley) from what you log. For curls, a practical setup is:

• Weight and reps: the stack setting and the reps you completed.
• RPE or RIR: how hard the set was, so a set of 10 at RIR 3 is not confused with 10 at RIR 0.
• Notes: the machine brand, seat or pad setting and your lowering tempo, such as "Brand X, pad on 4, 3 s down".

Machine settings drift between gyms, so a note is often the only way to explain why a number moved. The progress page shows per-lift trends, which is where keeping seated and lying curls separate pays off.

Common mistakes

• Treating the trial as settled. One study of 20 untrained adults supports a preference, not a rule.
• Comparing numbers across machines. Seat settings and levers differ. Compare a lift only to itself.
• Cutting the range short to move more weight.
• Doing curls and ignoring hinges. The hinge and the curl are not interchangeable, and the Crawford trial shows hinge-style work can grow hamstrings on its own.
• Changing everything at once. Swap one variable at a time, such as machine type or rep range, so you can tell what worked.

What are the limits of this evidence?

• One direct comparison. We found a single head-to-head trial of seated against prone curls. Until others repeat it, treat the 14% vs 9% figure as indicative.
• Untrained participants and 12 weeks. The trial describes beginners over one training block. Experienced lifters, who respond more slowly, may see a different gap.
• Small sample. Twenty people is small. The within-person design controls for individual differences, but it does not make the result universal.
• Muscle size, not strength or injury. The growth result does not tell you which curl makes you stronger or lowers hamstring injury risk.
• Modelling and reviews are indirect. The Morin paper uses modelled muscle length, and the Crawford and Arin-Bal papers do not compare curls at all. They provide context, not a ranking of the two machines.

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