MUSCLE DAMAGE FOLLOWING REPEATED BOUTS OF HIGH FORCE ECCENTRIC EXERCISE

This study was designed to test the hypothesis that performing repeate d bouts of eccentric exercise when muscles were not recovered from pre vious exercise would exacerbate muscle damage. Twelve nonweight-traine d males (21.7 +/- 2.4 yr) performed three sets of 10 eccentric actions of the elbow flexors (ECC) using a dumbbell that was set at 80% of th e preexercise maximal isometric force level. This same exercise was re peated 3 and 6 d after the first exercise. Maximal isometric force, re laxed and flexed elbow joint angle, muscle soreness, plasma creatine k inase, and glutamic-oxaloacetic transaminase activities were assessed. Ultrasound images were taken from the upper arm. These measures (exce pt soreness) were assessed immediately before and after each eccentric exercise bout (ECC1, ECC2, and ECC3) and 3 d after ECC3. Soreness was assessed prior to ECC1 and once a day for 9 d thereafter. All criteri on measures changed significantly (P < 0.01) after ECC1. ECC2 and ECC3 performed 3 and 6 d after ECC1 did not exacerbate damage and did not appear to slow the recovery rate. Increased echointensity in ultrasoun d images was demonstrated following ECC1, but no indication of increas ed damage was found after ECC2 and ECC3. Strenuous exercise performed with ''damaged'' muscles did not exacerbate damage or affect the repai r process.