★ 4.6
Seated or lying leg curl: which suits your goal?
“Nordbeltは簡単に固定でき、安定感があります。”
Seated curls have a research advantage for muscle growth, but that does not settle every training decision. Choose by goal, machine fit and repeatable technique.
無料10週間トレーニングプロトコル無料プランを受け取る ↓Your training goal comes first when choosing a seated or lying leg curl. For muscle growth, one direct comparison favoured the seated version; lying curls remain an option when that machine fits you well (Maeo et al., 2021). More muscle volume does not prove better protection from injury. Choose according to your goal, a suitable setup and a movement you can repeat. The biggest number on the weight stack does not settle the comparison.
If you later want to add Nordic curls at home alongside machine curls, see how Nordbelt secures your ankles without a training partner. That setup needs a suitable, stable anchor and enough room to catch yourself. The tool is not a leg curl machine and does not decide whether seated or lying curls are the more practical choice for your goal.
What changes with hip position?
On a seated leg curl machine, your hip is flexed. On a lying machine, your thigh is more in line with your torso, although the angle varies by machine. The hamstrings that cross both the hip and knee therefore work at a longer length when seated. The short head of the biceps femoris crosses only the knee and does not follow this difference in the same way (Maeo et al., 2021).
This does not mean lifting your torso off a lying machine to imitate the seated position. Choose the exercise you intend to do and use its intended supports. If you cannot sit or lie comfortably in the correct position, ask for help adjusting it. The separate guide to adjusting a leg curl machine for hamstrings covers the machine axis, roller and supports. Here, we are comparing the training choice.
What do we know about muscle growth?
In one study, twenty healthy adults trained one leg seated and the other lying for twelve weeks. Both legs followed the same prescribed training dose. Total hamstring muscle volume measured by MRI increased by about 14% when seated and 9% when lying. The advantage concerned the muscles crossing two joints; there was no clear difference for the short head (Maeo et al., 2021).
This makes seated curls an evidence-based starting point when muscle growth is your main reason for training and both machines fit you. It does not make lying curls pointless. The sample was small, and the result belongs to these machines, participants and training conditions. The percentages do not predict your own results and are not a reason to suddenly copy a research programme.
Illustration of a lying curl with bent knees. The image does not show the study equipment or participants and does not prescribe an end angle.
Does a heavier load mean greater strength gains?
A small laboratory study in seven men compared, among other conditions, knee flexion with the hip extended and flexed. Peak torque and total work were higher with the hip flexed. The researchers used isokinetic equipment and MRI signal changes to examine immediate differences (Yanagisawa & Fukutani, 2020). This was not a long-term contest between two training programmes.
Nor can you directly compare the kilograms on two gym machines. Their lever arms, cable arrangements and settings can differ. Moving more plates seated than lying does not demonstrate a personal strength gain. Compare progress on the same machine with the same settings and technique. If you switch machines, treat the new load as a fresh starting point.
Do not use the burning sensation during a set to rank future results either. An experience during one session and muscle growth over several weeks are different things. You do not automatically have to choose the version that feels hardest.
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✓研究に基づく内容
Van Dykら（2019）：NHEを含むプログラムのメタ分析。Nordbeltや本プログラム自体の効果を測定したものではありません。
Start with one clear training question
First decide what you want the exercise to achieve. Then use this practical comparison: it is a decision aid, not a tested training protocol.
| Your situation | A reasonable starting point | What to check first |
|---|---|---|
| Muscle growth is your main goal and both machines fit | Try seated curls first, based on the direct comparison (Maeo et al., 2021). | Can you sit steadily and repeat the movement without symptoms? |
| Only a suitable lying machine is available | Use it if you can adjust it to fit. | Does the exercise fit your current plan without adding sets to compensate? |
| You already follow a programme with one version | Keep that version while the task and execution remain clear. | Discuss a change if someone supervises your training. |
| A position causes pain or obvious pressure | Stop that version. | Have the setup and symptoms assessed; another position is not a diagnosis. |
You do not need both versions in every session. If you want to switch, avoid changing the machine, sets, load and tempo all at once. Otherwise, you will not know what a different experience relates to. Note what you chose and why: for example, seated because muscle growth is the goal and the machine fits well.
Muscle damage is not an injury outcome
A separate follow-up to the twelve-week study measured changes after eccentric exercise. The two trained positions did not differ significantly on those outcomes. These were laboratory measures of muscle damage and temporary strength loss, not the number of sports injuries during a season (Maeo et al., 2021).
Do not choose a machine on the promise that it prevents or heals a hamstring injury. With an acute injury or persistent pain, deciding what load is appropriate now matters more than this general comparison. Discuss that with a doctor or physiotherapist. Sharp pain, new swelling or a clear loss of strength is a reason to stop the set and seek assessment.
When is a Nordic curl a separate choice?
During a machine curl, your lower leg moves against a machine arm. During a Nordic curl, your ankles remain secured while you control your body's forward movement from kneeling. You therefore cannot judge one exercise by the load or sensation of the other. For this movement, read the Nordic hamstring curl guide.
If you later add it, provide knee padding, a non-slip surface and clear space to catch yourself with your hands. Use only a suitable, sturdy, fully closed door from the intended side, or a bench or fence that cannot slide or tip. Check the attachment under light tension first. Tightening a strap does not make an unsuitable anchor suitable.
Start upright, keep the line from knees to shoulders as consistent as possible and make a small lowering movement. Lower under control, catch yourself in time with your hands and use them to help you return. For changes in posture, see the separate guide to common Nordic curl mistakes. Follow the Nordbelt setup guide for attachment instructions. This additional exercise choice does not settle the seated-versus-lying comparison.
Context image for recording your exercise choice. The notebook contains no readable training programme or research results.
Frequently asked questions
Is a seated leg curl always better than a lying one?
No. For muscle growth, the direct comparison above gives a reason to consider seated curls, but availability, suitable adjustment and your training task still matter. A research advantage on one outcome does not make a version a universal winner.
Do I need to combine seated and lying leg curls?
That is not a requirement established by this comparison. First choose one version that fits your goal and current programme. Do not automatically add the other on top of all your existing sets. Discuss a change with your trainer if you follow a supervised plan.
Can I carry the same weight over to another machine?
No: do not treat the number as a fixed conversion. The machines can have different lever arms and resistance paths. Start with an appropriately light load and establish again what you can control with the intended technique.
Which version should I choose if my hamstring hurts?
Do not use pain as a home test for the best machine. Stop a painful movement and have persistent, worsening or unexplained symptoms assessed. A general comparison of seated and lying curls does not replace an individual examination or rehabilitation plan.
