There is no single best hamstring exercise for every goal. The Nordic hamstring curl produces the highest overall muscle activation of any bodyweight hamstring movement and cuts hamstring injury rates in half. But for building size, the seated leg curl outperforms the lying version. And for athletes chasing sprint speed, hip-dominant movements like the Romanian deadlift train the hamstrings in a way that transfers more directly to acceleration. The best approach combines at least two types of hamstring exercises, and understanding why will help you pick the right ones.
Why One Exercise Isn’t Enough
Your hamstrings are not a single muscle. They’re a group of four: three run from your hip to below your knee (the semitendinosus, semimembranosus, and long head of the biceps femoris), and one connects only across the knee (the short head of the biceps femoris). Because those three longer muscles cross two joints, they do two distinct jobs: extending your hip (think deadlifts) and bending your knee (think leg curls). No single exercise loads both functions equally.
Research on elite female track and field athletes classified common hamstring exercises into two categories: those that preferentially activate the inner hamstrings (semitendinosus) and those that favor the outer hamstrings (biceps femoris long head). Lunges, kettlebell swings, and single-leg Romanian deadlifts lit up the inner hamstrings more. The fitball (stability ball) leg curl was the only exercise that selectively activated the outer biceps femoris during the shortening phase. Exercises like the Nordic curl and sliding leg curl activated both sides roughly equally. If you only ever do one movement, you’re likely leaving part of the muscle group undertrained.
Nordic Hamstring Curl: Best for Injury Prevention
The Nordic hamstring curl is the most studied hamstring exercise in sports medicine, and the data is hard to argue with. A systematic review and meta-analysis covering 8,459 athletes found that training programs including the Nordic curl reduced hamstring injuries by up to 51%. It essentially halves your injury risk across multiple sports.
The Nordic curl works by loading your hamstrings eccentrically, meaning the muscles lengthen under tension as you slowly lower your torso toward the ground from a kneeling position. This type of loading increases the resting length of muscle fibers in the outer hamstring. After just three weeks of Nordic curl training, researchers measured a 21% increase in fiber length in the lower portion of that muscle. Longer fibers are more resistant to being overstretched during explosive movements like sprinting, which is exactly when most hamstring tears happen.
In terms of raw muscle activation, the Nordic curl and its variations produce the highest levels among common strengthening exercises. Still, even the Nordic curl only reaches about 40 to 65% of the activation your hamstrings produce during an all-out sprint for the inner muscles, and 18 to 40% for the outer biceps femoris. Sprinting remains the most demanding hamstring activity by a wide margin, which is part of why it’s also when injuries occur.
Seated Leg Curl: Best for Muscle Growth
If your primary goal is bigger hamstrings, the seated leg curl has a clear advantage over the lying (prone) version. A 12-week study had participants train one leg with the seated curl and the other with the prone curl, using the same weight, sets, and reps. MRI scans showed the seated leg gained 14% in total hamstring volume compared to 9% for the prone leg. Every two-joint hamstring muscle grew more with the seated variation, with individual muscles gaining between 8% and 24% more volume.
The reason comes down to muscle length during the exercise. When you sit with your hips flexed, the long hamstring muscles start in a stretched position. Training a muscle at longer lengths creates a stronger growth stimulus. When you lie face down, your hips are neutral and those same muscles start shorter, reducing the stretch-related tension that drives adaptation. If your gym has both machines, the seated version is the better choice for hypertrophy.
That said, ACE Fitness research comparing eight hamstring exercises found that the prone leg curl actually produced the highest biceps femoris activation of any exercise tested. Six of the eight exercises, including the seated curl, the Romanian deadlift, and the glute-ham raise, produced significantly lower outer hamstring activation than the prone curl. So the prone curl isn’t useless. It just doesn’t grow muscle as effectively despite the higher activation signal, likely because the stretch stimulus matters more for long-term size gains than peak electrical activity alone.
Romanian Deadlift: Best for Athletic Performance
The Romanian deadlift trains your hamstrings through hip extension rather than knee bending. This matters for athletes because the hamstrings contribute heavily to horizontal force production during sprint acceleration. When you push off the ground while running, your hamstrings are working primarily at the hip, not the knee.
A six-week training protocol compared the Romanian deadlift directly against the Nordic curl for their effects on sprint performance and hamstring injury risk factors. Despite the Nordic curl’s well-documented injury prevention benefits, researchers noted that the Romanian deadlift may offer similar or even greater benefits for sprint speed because it more closely mimics the hip-extension demands of running.
The Romanian deadlift also allows for progressive overload with heavy weights in a way that bodyweight exercises like the Nordic curl cannot. You can add load week after week, making it a practical choice for long-term strength development. For anyone whose training revolves around running, jumping, or changing direction, including a hip-dominant hamstring exercise is essential.
Stability Ball Curl and Glute-Ham Raise
If you train at home or travel frequently, stability ball hamstring curls deserve attention. ACE research found they produced significantly higher inner hamstring activation than the prone leg curl, making them one of the better options for that part of the muscle group. They also challenge your core and require you to stabilize your hips, adding a coordination component that machine exercises skip.
The glute-ham raise without equipment (sometimes called a “natural” glute-ham raise, performed on the floor with your feet anchored) also produced significantly higher inner hamstring activation than the prone leg curl. However, the machine-based glute-ham raise performed worse for the outer hamstrings than a standard prone curl. The mechanics of the two versions differ enough that they shouldn’t be treated as interchangeable.
How to Combine Them
A practical hamstring program includes one hip-dominant and one knee-dominant exercise. The pairing you choose depends on your priorities:
- For injury prevention: Nordic hamstring curls paired with Romanian deadlifts. This covers both joint actions and gives you the eccentric loading that lengthens muscle fibers plus the hip-extension strength that protects during sprinting.
- For muscle size: Seated leg curls paired with Romanian deadlifts or stiff-leg deadlifts. The seated curl maximizes growth through the stretch position, while the deadlift variation hits the hamstrings from the hip side.
- For home training: Nordic curls (feet anchored under a couch or heavy object) paired with single-leg Romanian deadlifts using a dumbbell or kettlebell. Stability ball curls can substitute for Nordics if you lack an anchor point.
Training each movement twice per week is enough to drive meaningful adaptation. The Nordic curl in particular responds well to moderate volume: three to four sets of five to eight slow, controlled reps is a common protocol used in the injury prevention research. For seated curls and Romanian deadlifts aimed at growth or strength, standard hypertrophy ranges of three to four sets of eight to twelve reps work well, with load increasing over time.