Less pain, same gain? A randomized controlled trial comparing assisted- versus non-assisted Nordic Hamstring exercise training in elite youth football players.

INTRODUCTION

The Nordic Hamstring exercise (NHE) increases hamstring strength, but muscle soreness and excessive fatigue may hinder adoption. The assisted NHE (A-NHE), with an elastic band around the chest lowering the force in the eccentric lowering phase, may be a less demanding alternative. We investigated the effectiveness of A-NHE versus NHE on hamstring strength, muscle soreness, and perceived exertion.

METHODS

We randomized 31 youth elite football players (under-14 and -15) from a single professional football academy to either NHE or A-NHE, who performed the same supervised 8-week program. The A-NHE was performed with an elastic band, progressing from heavy to light assistance. A blinded tester assessed Nordic hamstring strength, while hamstring muscle soreness and perceived exertion were assessed during each session.

RESULTS

Intention-to-treat analysis showed no group by time interaction (p = 0.61) for Nordic hamstring strength. Both groups improved significantly (A-NHE mean difference: 3.7 kg, 95% CI [2.1; 5.3]; NHE mean difference: 3.2 kg, 95% CI [1.2; 5.2]) corresponding to approximately 20%. The NHE group reported significantly higher hamstring muscle soreness (beta = 1.77, p < 0.01) and perceived exertion (beta = 1.54, p < 0.01).

CONCLUSION

Eight weeks of assisted-versus regular Nordic Hamstring training led to similar strength gains, but with lower hamstring muscle soreness and perceived exertion.