Greater muscle damage induced by fast versus slow velocity eccentric exercise

Area of Science:

• Exercise Physiology
• Muscle Physiology
• Sports Science

Background:

• The impact of contraction velocity on exercise-induced muscle damage is debated.
• Few human studies have investigated this relationship, particularly in untrained individuals.

Purpose of the Study:

• To determine if eccentric exercise velocity influences the magnitude of muscle damage.
• To compare muscle damage responses between slow velocity (SV) and fast velocity (FV) eccentric contractions.

Main Methods:

• Twelve untrained subjects performed isokinetic eccentric elbow flexions at SV (30°/s) and FV (210°/s) in a counterbalanced manner.
• Standardized time under tension (120s) was maintained by adjusting the number of repetitions (30 for SV, 210 for FV).
• Muscle damage was assessed via maximal voluntary torque, range of motion, upper arm circumference, soreness, and plasma creatine kinase (CK) activity.

Main Results:

• Both protocols induced significant muscle damage, but FV resulted in greater reductions in isometric and dynamic torque (~55% vs. ~30% for SV) and slower recovery.
• FV led to significantly larger decreases and delayed recovery in range of motion and relaxed elbow joint angle.
• Increased upper arm circumference, soreness, and peak plasma CK activity were significantly greater after FV compared to SV.

Conclusions:

• Fast velocity eccentric exercise induces greater muscle damage than slow velocity eccentric exercise when time under tension is equated.
• Untrained individuals experience more pronounced strength deficits, functional impairments, and biochemical markers of muscle damage with faster eccentric contractions.