Leg curl vs Romanian deadlift for hamstrings

Ask which exercise is best for hamstrings and you will get a fight. One camp swears by the Romanian deadlift, the other by the leg curl. The honest answer is that they are not really competing, because your hamstrings do two different jobs and these two exercises each train one of them. The hamstrings both bend your knee and extend your hip, and an exercise that loads one of those jobs does not automatically train the other well. Once you understand that split, the question stops being which is better and becomes how to use both. That is not a cop out, it is what the research on how hamstrings actually grow keeps pointing to.

The short version

Your hamstrings do **two jobs**: they **bend the knee** and **extend the hip**. Each exercise trains mostly one.
The Romanian deadlift is a hip movement. It loads the hamstrings in a big stretch and builds the upper and mid part of the muscle, plus your glutes and lower back.
The leg curl is a knee movement. It trains the hamstrings' knee bending job, which the Romanian deadlift barely touches, and hits the lower hamstring more.
Research on muscle imaging suggests different exercises work different regions of the hamstrings, which is why variety matters.
The best answer for most people is both: a hip movement for size and the stretch, plus a knee movement to cover the job it misses.

The hamstrings have two jobs

The hamstrings are a group of muscles running down the back of your thigh, and they cross two joints. At the hip, they extend your leg backward, driving movements like standing up from a bend. At the knee, they bend your leg, curling your heel toward your backside. Because they do both, an exercise that trains one job does not necessarily train the other.

This is the single most important thing to understand in this comparison. The Romanian deadlift is a hip movement: your knees stay relatively fixed and the action happens at the hip. The leg curl is a knee movement: your hip stays fixed and the action happens at the knee. They are loading the same muscle group through two different functions, which is exactly why they are not interchangeable.

Why this settles the argument

If someone tells you the Romanian deadlift makes leg curls pointless, ask them how the Romanian deadlift trains knee flexion. It barely does. The two exercises are answering different questions, so the interesting move is to use both, not to pick a winner.

The Romanian deadlift: hip hinge and stretch

The Romanian deadlift, often shortened to RDL, is a hip hinge. You hold a barbell or dumbbells, push your hips back, and let the weight travel down the front of your legs while your back stays flat and your knees stay only slightly bent. You feel a deep stretch in the hamstrings as you lower, then drive your hips forward to stand back up.

Trains the hip extension job of the hamstrings, plus your glutes and lower back, so it carries over to real world strength and to lifts like the deadlift.
Loads the hamstrings hard in a lengthened, stretched position, which appears to be a strong stimulus for growth.
Tends to bias the upper and middle portions of the hamstrings.
Uses more muscle and more weight, so it is more fatiguing and more technical. Rounding your back under load is the main risk to respect.

Form matters more here

Because the RDL loads your spine and can be heavy, keeping a flat back and a braced core is not optional. If your lower back rounds as you lower, shorten the range or lighten the weight. This is a movement where sloppy form has a real cost, unlike the more forgiving leg curl.

The leg curl: knee flexion in isolation

The leg curl, done lying, seated, or standing on a machine, has you bend your knee against resistance, curling your heel toward your backside. Your hip stays put and the movement happens purely at the knee. It isolates the hamstrings' knee bending job, which the RDL almost entirely skips.

Trains the knee flexion job of the hamstrings, the part a hip hinge does not cover.
Tends to involve the lower hamstring, nearer the knee, more than the RDL does.
Isolated and machine based, so it is easier on your lower back and simpler to learn and push close to failure safely.
The seated version trains the hamstrings while the hip is bent, and there is evidence this position, with the muscle at a longer length, is a good growth stimulus.

The low back friendly option

Because the leg curl does not load your spine, it is a great way to add hamstring volume when your lower back is already tired from squats and deadlifts. You can train it hard and close to failure without the fatigue cost of another heavy hinge.

What the research says about regional growth

This is where it gets genuinely interesting. Studies using muscle imaging to see which parts of the hamstrings work during different exercises have found that hip extension style movements and knee flexion style movements do not light up the muscle identically. They emphasise different regions and different individual muscles within the hamstring group.

For example, imaging work comparing exercises like the hip focused movements against knee flexion movements found meaningfully different patterns of muscle use across the hamstrings. Knee flexion exercises tend to involve certain muscles and lower regions more, while hip extension exercises emphasise others. The practical message is not that one is better, it is that relying on only one exercise leaves parts of the hamstrings undertrained.

	Romanian deadlift	Leg curl
Joint action	Hip extension (hinge)	Knee flexion (curl)
Also trains	Glutes, lower back	Mostly just the hamstrings
Region emphasised	Upper and middle hamstring	Lower hamstring, near the knee
Lower back load	High	Very low
Best for	Size, stretch, real world strength	Isolated volume, low back friendly work

The honest verdict

For complete hamstrings, do both. Use a hip hinge like the RDL as a main movement for size, the stretch, and strength, and add a leg curl to train the knee flexion job and lower hamstring it misses. If you only have time for one and want overall size and carryover, the RDL is the higher value pick, but you are leaving something on the table.

Questions people ask

Is the Romanian deadlift or leg curl better for hamstrings?

Neither is simply better, because they train different jobs of the hamstrings. The Romanian deadlift trains hip extension in a big stretch and also builds your glutes and lower back. The leg curl trains knee flexion, which the RDL barely touches, and works the lower hamstring more. For complete hamstrings, do both. If forced to pick one for overall size and carryover, the RDL is the higher value choice.

Do I still need leg curls if I do Romanian deadlifts?

If you want to fully develop your hamstrings, yes. The Romanian deadlift is a hip movement and barely trains the knee bending job of the hamstrings, which is exactly what the leg curl targets. Muscle imaging research shows the two exercises emphasise different regions, so adding leg curls covers a part of the muscle the RDL misses.

Which is safer for my lower back?

The leg curl, by a wide margin. It is a machine based isolation exercise that does not load your spine, so you can train it hard even when your lower back is fatigued from squats and deadlifts. The Romanian deadlift loads the lower back and demands strict form, with back rounding under load being the main risk to manage.

Can I build big hamstrings with only one of these?

You can make progress, but you will likely leave growth on the table. Because the two exercises train different functions and regions of the hamstrings, using only one undertrains part of the muscle. A hip hinge plus a knee curl covers both jobs, which is why most well built hamstring programs include both.

References

Bourne MN, et al. British Journal of Sports Medicine. Impact of the Nordic hamstring and hip extension exercises on hamstring architecture and morphology: implications for injury prevention. 2017. pubmed.ncbi.nlm.nih.gov/27660368
Yanagisawa O, Fukutani A. Journal of Human Kinetics. Muscle recruitment pattern of the hamstring muscles in hip extension and knee flexion exercises. 2020. pubmed.ncbi.nlm.nih.gov/32269647
American College of Sports Medicine. Medicine and Science in Sports and Exercise. Progression models in resistance training for healthy adults (position stand). 2009. doi.org/10.1249/MSS.0b013e3181915670

Last reviewed 18 July 2026. We check health-condition articles against current guidelines and update the date above when we do.