HEMATOLOGICAL AND ACUTE-PHASE RESPONSES ASSOCIATED WITH DELAYED-ONSETMUSCLE SORENESS IN HUMANS

Delayed-onset muscle soreness following unaccustomed or eccentric exer cise is associated with inflammation, tissue necrosis and the release of muscle enzymes (Newham et al. 1983). We have investigated the time course of changes in circulating leucocytes and serum levels of some a cute phase reactants, serum creatine kinase activity (CK) and muscle p ain after a 40-min bout of bench-stepping exercise in eight healthy un trained subjects. Leg muscle soreness was greatest 2 days after the ex ercise bout. Peak serum CK values [mean (SD) 540 (502) IU . 1(-1)] occ urred 1-7 days postexercise. Serum C-reactive protein (CRP) was unchan ged from pre-exercise levels [7.8 (3.4) mg . 1(-1)] immediately post-e xercise [7.9 (2.3) mg . 1(-1)] but rose to a peak of 17.0 (3.9) mg . 1 (-1) 1 day post-exercise, thereafter declining to basal levels. Serum levels of iron and zinc fell below pre-exercise levels for 1-3 days po st-exercise. Serum albumin, IgG and ISM fell below pre-exercise levels from 1 day post-exercise, reaching minimal values (about 80% of basal levels) at 7 days post-exercise. The exercise did not appear to signi ficantly affect serum levels of alpha-1-antitrypsin and alpha-1-acid g lycoprotein. Two and three days after the exercise bout the circulatin g numbers of total leucocytes, neutrophils, monocytes and basophils fe ll 15-20% below pre-exercise levels, whereas lymphocytes, eosinophils and platelets were unchanged. The results indicate that a rapid acute phase inflammatory response is initiated within 1 day of a bout of exe rcise that induces delayed-onset muscle soreness, and that any later t issue necrosis that may occur is not accompanied by further marked cha nges in acute-phase reactants such as CRP.