Progressive resistance training temporarily alters hamstring torque-angle relationship.

Area of Science:

• Biomechanics
• Exercise Physiology
• Muscle Physiology

Background:

• The torque-angle relationship is crucial for understanding muscle function and performance.
• Progressive resistance training (PRT) can modify neuromuscular properties.
• Differentiating the effects of eccentric versus concentric contractions on this relationship is important.

Purpose of the Study:

• To investigate the distinct effects of eccentric training (ECC) and concentric training (CON) on the muscle torque-angle relationship in young adults.
• To compare these effects against a control group (CTL).

Main Methods:

• Thirty young adults were randomized into ECC, CON, or CTL groups.
• ECC and CON groups underwent 3 weeks of progressive resistance training on hamstring muscles.
• Torque-angle relationships were measured pre-training and at 4, 11, and 18 days post-training.

Main Results:

• Concentric training (CON) shifted the angle of peak isometric torque towards knee extension post-training.
• Eccentric training (ECC) increased peak torque, especially at extended knee angles, and significantly shifted the peak torque angle towards knee flexion on days 4 and 11 post-training.
• These ECC-induced changes were temporary, with the torque-angle relationship returning to baseline by day 18.

Conclusions:

• Eccentric progressive resistance training induces a transient but significant adaptation in the hamstring muscle's torque-angle relationship, characterized by a shift towards knee flexion.
• Concentric training also alters the torque-angle relationship, but to a lesser extent and with a different directional shift.
• These findings highlight the distinct neuromuscular adaptations resulting from different modes of resistance training.