Velocity-specific and time-dependent adaptations following a standardized Nordic Hamstring Exercise training

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The Nordic Hamstring Exercise (NHE) is effective for selective hamstring strength- ening to improve muscle balance between knee flexors and extensors. The purpose of this study (within subject design of repeated measures) was to determine the effects of a standardized 4-week NHE training on thigh strength and muscle balance with concomitant kinetic and kinematic monitoring. Sixteen male sprinters (22 years, 181 cm, 76 kg) performed a standardized 4-week NHE training consisting of three sessions per week (each 3×3 repetitions). Six rope-assisted and six unassisted ses- sions were performed targeting at a constant knee extension angular velocity of ~15°/s across a ~90-100° knee joint range of motion. Kinetic (peak and mean mo- ment, impulse) and kinematic parameters (eg, ROM to downward acceleration, ROMDWA) were recorded during selected sessions. Unilateral isokinetic tests of con- centric and eccentric knee flexors and extensors quantified muscle group-, contrac- tion mode-, and velocity-specific training adaptations. Peak moments and contractional work demonstrated strong interactions of time with muscle group, contraction modes, and angular velocities (η2>.150). NHE training increased eccentric hamstring strength by 6%-14% as well as thigh muscle balance with biggest adaptations at 150°/s 2 weeks after NHE training. Throughout the training period significant increases (P<.001) of peak (η2=.828) and mean moments (η2=.611) became apparent, whereas the impulse and the ROMDWA of unassisted NHE repetitions remained unchanged (P>.05). A 4- week NHE training significantly strengthened the hamstrings and improved muscle balance between knee flexors and extensors. Despite the slow training velocity, biggest adaptations emerged at the highest velocity 2 weeks after training ended.
ZeitschriftScandinavian journal of medicine & science in sports
Seiten (von - bis)65-76
PublikationsstatusVeröffentlicht - 2018

ID: 3109667


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