Greater decrements in neuromuscular function following interval compared to continuous eccentric cycling

Area of Science:

• Exercise Physiology
• Muscle Physiology
• Sports Science

Background:

• Eccentric exercise is known to induce greater muscle damage and soreness compared to concentric exercise.
• The specific demands and consequences of continuous (CONT) versus interval (INT) eccentric cycling protocols remain less understood.

Purpose of the Study:

• To compare the physiological demands and recovery responses between work-matched continuous and interval eccentric cycling sessions.
• To investigate the impact of different eccentric cycling protocols on muscle function, soreness, and metabolic markers.

Main Methods:

• Fourteen healthy males participated in a crossover study involving both CONT and INT eccentric cycling.
• Measurements included maximal voluntary contraction (MVC), voluntary activation (VA), resting twitch force, muscle soreness, and creatine kinase (CK) at various time points.
• Metabolic demands (V̇O2peak, blood lactate) and rating of perceived exertion (RPE) were assessed during exercise.

Main Results:

• Both protocols induced significant decreases in MVC, twitch force, and VA immediately post-exercise.
• Interval eccentric cycling resulted in greater reductions in twitch force and prolonged recovery (48 hours) compared to CONT.
• Muscle soreness was significantly higher after INT eccentric cycling, while creatine kinase levels did not differ between protocols.
• Metabolic demands (V̇O2peak, blood lactate, RPE) were higher during INT eccentric cycling.

Conclusions:

• Interval eccentric cycling imposes greater acute physiological stress and leads to more pronounced decrements in muscle function and prolonged recovery compared to a work-matched continuous protocol.
• The increased muscle damage and soreness associated with INT eccentric cycling appear attributable to higher peak force production rather than extended time under tension.