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

Area of Science:

• Sports Science
• Biomechanics
• Exercise Physiology

Background:

• The Nordic Hamstring Exercise (NHE) is recognized for its efficacy in targeted hamstring strengthening.
• Improving muscle balance between knee flexors and extensors is crucial for athletic performance and injury prevention.

Purpose of the Study:

• To investigate the effects of a standardized 4-week NHE training program on thigh strength and muscle balance.
• To monitor kinetic and kinematic parameters during NHE execution.

Main Methods:

• Sixteen male sprinters underwent a 4-week NHE training regimen (3 sessions/week, 3x3 repetitions).
• Training included both rope-assisted and unassisted sessions at a controlled knee extension angular velocity (~15°/s).
• Kinetic (peak/mean moment, impulse) and kinematic (ROM_DWA) data were collected, alongside isokinetic tests for muscle group and contraction mode analysis.

Main Results:

• NHE training significantly increased eccentric hamstring strength by 6%-14% and improved thigh muscle balance.
• Peak strength adaptations were most pronounced at 150°/s, observed two weeks after training cessation.
• Significant increases in peak and mean moments were noted throughout the training period.

Conclusions:

• A 4-week NHE program effectively enhances hamstring strength and knee flexor-extensor muscle balance in sprinters.
• The training elicits significant strength adaptations, particularly at higher velocities, even when initiated at a slower training velocity.
• NHE is a valuable exercise for optimizing hamstring function and athletic performance.