Metabolic changes following eccentric exercise in trained and untrained men

The efects of one 45-min bout of high-intensity eccentric exercise (250 W) were studied in four male runners and five untrained men. Plasma creatine kinase (CK) activity in these runners was higher (P < 0.001) than in the untrained men before exercise and peaked at 207 IU/ml 1 day after exercise, whereas in untrained men the maximum was 2,143 IU/ml 5 days after exercise. Plasma interleukin-1 (IL-1) in the trained men was also higher (P < 0.001) than in the untrained men before exercise but did not significantly increase after exercise. In the untrained men, IL-1 was significantly elevated 3 h after exercise (P < 0.001). In the untrained group only, 24-h urines were collected before and after exercise while the men consumed a meat-free diet. Urinary 3-methylhistidine/creatinine in the untrained group rose significantly from 127 μmol/g before exercise to 180 μmol/g 10 days after exercise. The results suggest that in untrained men eccentric execise leads to a metabolic response indicative of delayed muscle damage. Regularly performed long distance running was associated with chronically elevated plasma IL-1 levels and serum CK activities with acute increases after an eccentric exercise bout.