We performed this study to evaluate the chronic effect of training on neutrophil functions in humans. Twenty-six university students (14 males and 12 females) with a mean age of 19.1±0.8 years were divided into the athlete group and the control group based on answers given to a written questionnaire. The capacity of circulating neutrophils to ingest bacteria (phagocytosis) and to produce superoxide (nitroblue tetrazolium reduction) was measured under resting conditions in the absence of training activities. In addition, we measured hematological and serum biochemical parameters. The present analyses revealed that the frequency of subjective symptoms concerning susceptibility to infections (sum of males and females) was higher in the athlete group than in the control group (p<0.05). In the investigation of males, hemoglobin and serum protein levels of the athlete group were lower than that of the control group (p<0.01, p<0.05, respectively). Although total and differential leukocyte counts, and phagocytic activity of neutrophils were not significantly different between the groups, superoxide productivity of neutrophils in the male athlete group was higher than that in the control group (p<0.05). Since significant differences were observed in hemoglobin and serum protein levels in the male athletes, the training is considered to have been intense. An increase was noted in the neutrophil superoxide production along with these changes, but no significant difference was observed in the phagocytic activity. Therefore, there is the possibility of superoxide overproduction, which may lead to tissue damage.
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