Effect of different rest interval lengths of resistance exercise on lipid peroxidation and creatine kinase responses

The purpose of this study was to determine the effects of two resistance exercise (RE) protocols with different rest intervals between sets on oxidative stress and exercise-induced muscle damage. For this purpose, twenty untrained males voluntarily participated in the research and were randomly assigned to one of two resistance exercise groups: a) a shorter inter-set rest interval of 90 second (RI-90; n=10); or b) a longer rest interval of 180 second (RI-180; n=10). Resistance exercise in both groups consisted of chest press (CP), "lat" pull down (LP), leg extension (LE), leg curl (LC), and back squat (BS) exercises; these were done at a load of six repetitions maximum (6 RM). Blood samples were collected from the antecubital vein pre-exercise, immediately post-exercise, 6, 24, and 48 hours post-exercise, and analyzed for malondiadehyde (MDA) concentration and creatine kinase (CK) activity. The results indicated that both RI-90 and RI-180 caused significant changes in the MDA response (p=.003 and p=.036 in RI-90 and RI-180, respectively); MDA significantly increased six hours post-resistance exercise in both groups. Creatine kinase activity significantly increased at the 24-hour point post-exercise in both groups and continued for 48 hours post-exercise (p=.000 for RI-90 and RI-180). There was no significant difference between corresponding MDA and CK values of two groups. We conclude that the rest interval between sets of resistance exercise does not affect oxidative stress and myocellular damage. Key words: weight training, oxidative stress, malondialdehyde, recovery, muscle cell damage