ADAPTATION TO ECCENTRIC EXERCISE - EFFECT ON CD64 AND CD11B CD18 EXPRESSION/

The primary purpose of the study was to examine circulating neutrophil s and monocytes and their plasma membrane expression of CD64, CD11b, a nd CD18 after two bouts (B1 and B2) of eccentric exercise. Subjects (n = 10) performed 25 forced-lengthened contractions of the forearm flex ors on two occasions separated by 3 wk. Blood samples were obtained be fore exercise and at 1.5, 6, 12, 24, 48, 72, and 96 h of recovery. CD6 4, CD11b, and CD18 expression was determined via direct immunofluoresc ence and used as an indicator of neutrophil and monocyte activation. C reatine kinase activity (B1 = 1,390, B2 = 108 U/l), myoglobin (B1 = 16 3, B2 = 41, ng/dl), and muscle soreness and tenderness were higher (P < 0.01) after B1 compared with B2. Neutrophils at 6, 12, and 96 h were higher (P < 0.05) for B1 vs. B2. CD11b expression on neutrophils was 2.7-fold higher at 72 h for B1 vs. B2. CD64 expression on neutrophils at 72 and 96 h was 1.4- and 1.9-fold higher, respectively, for B1 vs. B2. At 72 and 96 h, CD18 and CD64 expression on monocytes was 1.3-fold higher for B1 vs. B2. The observed changes were not significantly cor related with changes in creatine kinase activity or myoglobin. In conc lusion, the adaptation to eccentric arm exercise was associated with a reduction in circulating neutrophils and a lower state of neutrophil and monocyte activation.