THE IMPACT OF A REPEATED BOUT OF ECCENTRIC EXERCISE ON MUSCULAR STRENGTH, MUSCLE SORENESS AND CREATINE-KINASE

The purpose of this study was to determine if there were any beneficial or detrimental effects regarding delayed onset muscle soreness (DOMS), serum creatine kinase (CK), and maximum concentric strength at 80% of 1-RM(conc), if a bout of eccentric exercise was repeated at 48h after an initial bout. A secondary purpose was to determine whether unaccustomed eccentrics might affect plasma cholesterol (TC). Twenty-six men were randomly assigned to a control (Group 1) or experimental group (Group 2). Both groups performed three sets (12 repetitions per set) of the eccentric phase of a chest press, at 80% of one repetition maximum (1-RM(conc)); Group 2 repeated this exercise 48h later. DOMS and CK were measured before, and every 24h for 8 days after; TC was measured before, and every 24h for 4 days. Maximum strength during the concentric phase of a chest press (1-RM(conc)) was measured before and at 48-h intervals after. A repeated measures analysis of variance revealed a significant time effect (P < 0.05) for DOMS, CK and strength, but no significant difference between groups (P < 0.05). An interesting finding was the significant (P < 0.05) reduction in TC at 24, 48 and 72h, after exercise in both groups, which we hypothesized was associated with cellular repair. From these results we concluded that when a bout of eccentrics is repeated 48 h after an initial bout, there is no change in the characteristic time-course and/or intensity of DOMS, CK or 1-RM(conc).