Eccentric Hamstring Torque Production and Muscle Activity in Unassisted Versus Assisted Nordic Hamstring Exercises

Area of Science:

• Biomechanics
• Exercise Physiology
• Sports Medicine

Background:

• The Nordic Hamstring Exercise (NHE) is crucial for hamstring injury prevention.
• Understanding variations in NHE execution is vital for optimizing training.
• Eccentric strength and muscle activation patterns are key performance indicators.

Purpose of the Study:

• To compare hamstring eccentric torque and muscle activity between conventional unassisted (CNHE) and assisted (ANHE) Nordic Hamstring Exercises.
• To evaluate different variations of the ANHE for maximal eccentric torque production.
• To identify NHE variations that align with injury kinematics.

Main Methods:

• Twelve participants performed five maximal intensity NHE variations.
• Maximal hamstring eccentric torque production (Tmax) and electromyography integrals were measured.
• Torque-time integral and root mean square at Tmax were calculated for seven muscles.

Main Results:

• ANHE demonstrated significantly higher Tmax and torque-time integral than CNHE.
• ANHE showed greater muscle activity in biceps femoris, semitendinosus, and gastrocnemius muscles compared to CNHE.
• Unilateral ANHE simulating late-swing (ANHELSU) yielded the highest Tmax.

Conclusions:

• ANHE significantly enhances hamstring eccentric torque and muscle activation over CNHE.
• ANHELSU is particularly effective for maximizing eccentric torque, aligning with injury prevention strategies.
• Increased muscle length and time under tension contribute to enhanced performance in ANHE.