Assisted or unassisted Nordic Hamstring Exercise? - Resistance exercise determinants at a glance

Area of Science:

• Sports Science
• Biomechanics
• Exercise Physiology

Background:

• The Nordic Hamstring Exercise (NHE) is crucial for knee flexor strengthening.
• Unassisted NHEs may limit muscle activation and assessment accuracy due to fatigue and insufficient eccentric strength.
• Optimizing NHE execution is vital for effective training and injury prevention.

Purpose of the Study:

• To compare kinetic and kinematic parameters between assisted and unassisted Nordic Hamstring Exercises (NHEs).
• To evaluate the impact of assistance on exercise execution quality, fatigue, and variability.
• To determine the optimal execution mode for maximizing neuromuscular adaptations.

Main Methods:

• Sixteen male sprinters performed 3 sets of 3 repetitions of assisted and unassisted NHEs.
• Kinetic parameters (peak moment, impulse) and kinematic parameters (time under tension, ROM_DWA) were measured.
• Statistical analysis compared differences between execution modes and across repetitions.

Main Results:

• Assisted NHEs showed significantly higher impulses, time under tension, and ROM_DWA compared to unassisted NHEs.
• Unassisted NHEs resulted in greater inter-repetition fatigue, evidenced by increased angular velocity and decreased impulse and ROM_DWA.
• Assisted execution led to higher quality movements and reduced between-participant variability.

Conclusions:

• Assisted NHEs enhance exercise execution quality, ensuring greater range of motion and controlled movement.
• Assistance mitigates fatigue and reduces variability, potentially improving neuromuscular adaptations and assessment accuracy.
• Even 3x3 repetitions of NHEs can induce significant fatigue, highlighting the importance of proper execution and recovery.