Delayed onset muscle soreness and damage
The aims of the studies undertaken were to investigate the physiological and serum biochemical changes associated with muscle damage, and to test possible treatments for this condition. Initial studies examined the effects of walking 37 km daily for 4 days and of running 21.1 km and 25.6 km road race events in different groups of subjects. Prolonged walking produced little soreness, but daily increases in serum creatine kinase (CK) activity were recorded. In the two running studies, delayed increases in the serum activity of the enzymes CK, lactate dehydrogenase (LD) and aspartate transaminase (AST) were observed, as were changes in the CK and LD isoenzyme pattern. In a further study, the CK-MM isoform response to a maximal eccentric arm exercise was studied in 8 subjects. Although total CK activity continued to increase for 5 days after exercise, the CK MM1:MM3 ratio peaked at 48 h after exercise, when muscle soreness also peaked. Two non-steroidal anti-inflammatory drugs were assessed for their effectiveness in the muscle soreness condition. Diclofenac and ibuprofen were tested in double-blind crossover studies in which drug or placebo were administered before and after two bouts of 45 minutes downhill running. Neither drug proved effective in reducing muscle soreness or serum enzyme changes after the eccentric exercise. The effect of prior vitamin C supplementation on the same parameters was assessed, but this treatment also proved ineffective. A final study examined the effect of exercise during the period of muscle soreness and damage. In this study, a light eccentric exercise bout was performed 24 h after a heavy eccentric bout, using the same arm muscles. Performance of the light bout did not alter the symptoms of muscle soreness, but did effect serum CK activity changes and resistance to muscle fatigue during later eccentric exercise.