Shift of peak torque angle after eccentric exercise.

Area of Science:

• Exercise Physiology
• Muscle Mechanics
• Biomechanics

Background:

• Muscle contractions are classified as concentric (shortening), eccentric (lengthening), or isometric (static).
• Eccentric contractions are known to induce greater muscle damage and soreness compared to concentric contractions.
• Understanding the specific effects of submaximal eccentric exercise on muscle mechanical properties is crucial for training and rehabilitation.

Purpose of the Study:

• To investigate changes in quadriceps muscle mechanical properties after a submaximal concentric-eccentric stepping exercise protocol.
• To compare the effects of eccentric versus concentric contractions on muscle function and soreness.
• To determine if submaximal eccentric exercise alters the angle-torque relationship of the quadriceps muscle.

Main Methods:

• Twenty-four healthy, untrained subjects performed a 10-minute stepping exercise.
• The dominant leg performed eccentric contractions, while the non-dominant leg performed concentric contractions.
• Quadriceps isokinetic peak torque, peak torque angle, and muscle soreness were measured at baseline, immediately post-exercise, and at 1 and 2 days post-exercise.

Main Results:

• No significant changes in peak torque were observed for either eccentric or concentric exercise.
• A significant shift in the peak torque angle to longer muscle lengths was found in the eccentrically-exercised leg post-exercise.
• Eccentric exercise resulted in significantly higher muscle soreness at 1 and 2 days post-exercise compared to concentric exercise.

Conclusions:

• Submaximal eccentric exercise can alter muscle properties, specifically shifting the angle-torque relationship towards longer muscle lengths.
• These changes occur without a significant deficit in peak muscle force production.
• Eccentric exercise elicits a greater delayed onset muscle soreness response compared to concentric exercise following a submaximal protocol.