Acute Inflammatory, Cortisol, and Soreness Responses to Supramaximal Accentuated Eccentric Loading

Area of Science:

• Exercise Physiology
• Sports Science
• Muscle Physiology

Background:

• Eccentric loading is a key component of resistance training, influencing muscle adaptation and recovery.
• Understanding the physiological responses to different eccentric loading protocols is crucial for optimizing training strategies.
• Accurate measurement of time under tension, hormonal, inflammatory, and perceptual responses is vital for exercise science research.

Purpose of the Study:

• To compare the acute inflammatory, cortisol, and perceived soreness responses between supramaximal accentuated eccentric loading (AEL) and traditional resistance exercise (TRA) protocols.
• To investigate differences in time under tension (TUT) between AEL and TRA protocols during resistance exercise.
• To evaluate the effects of AEL and TRA on muscle adaptations, specifically vastus lateralis muscle thickness and echo intensity.

Main Methods:

• Twenty-one resistance-trained men participated in a randomized crossover study, completing AEL and TRA protocols separated by 48 hours.
• Protocols included AEL at 120/65% and 120/80% of 1RM, and TRA at 65/65% and 80/80% of 1RM.
• Measurements included eccentric time under tension (ETUT), total time under tension (TTUT), vastus lateralis muscle thickness and echo intensity via ultrasonography, salivary cortisol, and perceived soreness.

Main Results:

• Initial repetitions of AEL protocols showed longer ETUT and TTUT compared to TRA protocols.
• No significant overall protocol effect was found for ETUT and TTUT.
• Moderate changes in echo intensity were observed, while muscle thickness changes were trivial. Salivary cortisol decreased post-exercise, and perceived soreness increased at 24 hours for AEL80.

Conclusions:

• The acute inflammatory, cortisol, and perceived soreness responses following AEL were comparable to TRA.
• These findings suggest that AEL and TRA protocols elicit similar recovery patterns.
• Further research may explore long-term adaptations and optimal implementation of AEL in training programs.