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Metabolic changes following eccentric exercise in trained and untrained men
Journal of Applied Physiology (Bethesda, Md. : 1985)
|November 1, 1986
Summary
Eccentric exercise causes delayed muscle damage in untrained individuals, indicated by elevated creatine kinase (CK) and interleukin-1 (IL-1). Trained runners show chronically higher CK and IL-1 levels without acute exercise-induced increases.
Area of Science:
- Exercise Physiology
- Sports Medicine
- Biochemistry
Background:
- Eccentric exercise, characterized by muscle lengthening under load, is known to induce muscle damage.
- Biomarkers such as creatine kinase (CK) and interleukin-1 (IL-1) are commonly used to assess muscle damage and inflammation.
- Differences in exercise history may influence the physiological response to eccentric exercise.
Purpose of the Study:
- To investigate the acute effects of high-intensity eccentric exercise on plasma CK and IL-1 levels in trained runners versus untrained men.
- To assess markers of muscle damage and metabolic response following eccentric exercise in untrained individuals.
- To compare the chronic inflammatory status (IL-1) and baseline muscle damage markers (CK) between trained and untrained individuals.
Main Methods:
- Four trained male runners and five untrained men performed a 45-min bout of high-intensity eccentric exercise (250 W).
- Plasma CK and IL-1 levels were measured before and at various time points after exercise.
- Urinary 3-methylhistidine/creatinine ratios were analyzed in untrained men on a meat-free diet before and after exercise.
Main Results:
- Untrained men exhibited significantly higher peak plasma CK levels (2,143 IU/ml at 5 days) compared to trained runners (207 IU/ml at 1 day).
- Plasma IL-1 significantly increased in untrained men 3 hours post-exercise, but not in trained runners.
- Urinary 3-methylhistidine/creatinine, a marker of muscle protein breakdown, rose significantly in untrained men after exercise.
Conclusions:
- High-intensity eccentric exercise induces a delayed metabolic response indicative of muscle damage in untrained individuals.
- Trained runners demonstrate chronically elevated plasma IL-1 and serum CK, suggesting adaptation to regular training.
- Eccentric exercise does not cause acute increases in IL-1 or CK in endurance-trained athletes, highlighting training-induced resilience.