Nordic curls can shift hamstring peak torque toward a straighter knee
In short
A review of 19 studies involving 427 adults aged 18–36 found a tendency for eccentric hamstring training to shift peak torque toward longer muscle lengths. Reported changes were −17.3° ±11.7° for seated eccentric knee flexion and −13.5° ±4.8° for Nordic hamstring exercise. GRADE certainty was low, and the angle changes do not establish injury prevention or better deadlift performance.
After eccentric hamstring training, the knee angle producing peak torque tended to move toward longer muscle lengths. Of 19 studies involving 427 participants aged 18–36, 15 reported this direction of change and nine groups showed significant shifts. That is not evidence of an identical response in every participant or training program.
What does a change in peak torque angle mean?
Torque is rotational force at a joint; peak torque angle identifies where knee-flexion torque is greatest. Reported shifts were −17.3° ±11.7° for seated eccentric knee flexion and −13.5° ±4.8° for Nordic hamstring exercise. Here, the negative sign indicates movement toward a more extended knee, not a loss of strength.
Why does strength at longer lengths matter?
Hamstrings also work while lengthened. Late swing in sprinting, after the leg reaches forward and before foot contact, loads them in a lengthened position. The bottom of an RDL or deadlift offers another practical example of producing force while stretched. These movements have different joint conditions from a knee-flexion test, so a laboratory angle shift does not automatically establish better sporting or lifting performance.
Where can Nordics fit into a big-three program?
A programming example is a small amount of assisted Nordic work after the main lower-body lifts, or leg curls with a controlled lowering phase. One assisted set of 3–5 reps is a modest starting example; assess recovery before the next lower-body session. This is not a proven optimal prescription, and the seated eccentric knee-flexion results cannot be assigned to every leg-curl machine.
Lifters working on deadlift lockout or using RDLs can consider the accessory, but this review did not test lockout improvements. Record big-three and accessory sets and reps in fairlift to review weekly volume. If soreness reduces performance in the next deadlift session, reduce the added work.
GRADE certainty was low for every comparison, and participants were adults aged 18–36. These findings alone do not establish injury prevention. Nordics can cause substantial soreness when first introduced; start with low volume.
Frequently asked questions
How much did Nordics change the peak torque angle?
Reported changes were −13.5° ±4.8° for Nordic hamstring exercise and −17.3° ±11.7° for seated eccentric knee flexion. The negative sign indicates a shift toward a more extended knee, not a predicted change for each individual.
Does changing peak torque angle prevent hamstring injuries?
This review examined the angle at which peak torque occurs and did not establish fewer injuries. With low GRADE certainty, the angle change alone cannot prove a preventive effect.
Will Nordic curls improve deadlift lockout?
The review did not test deadlift lockout or one-rep max improvements. An angle adaptation measured during knee flexion cannot be treated as equivalent to improved hip-hinge performance.
How much Nordic work should I start with in a big-three routine?
One practical starting example is one assisted set of 3–5 reps after the main lower-body work, followed by monitoring recovery. That is not a research-established optimal dose; initial soreness can be substantial, so keep volume low.
Source: PubMed