The purpose of the present study was to investigate the effect of one session of progressive aerobic exercise on innate immune system of young and adult athletes. For this purpose, 15 young athletes with mean age of 14.33 ± 1.30, and 15 adult athletes with mean age of 24.15 ± 1.08, volunteerly participated. The progressive aerobic exercise (Bruce protocle) was executed to the point of exhaustion. Blood samples were taken before, immediately after, and one houre after the exercise. The statistical analysis used in this study was the analysis of variance with repeated measures (R-ANOVA) The result indicated a significant relationship between different phases of blood sampling. The post hoc (LSD) lest was also used to find the significant differences between each pair of phases (at P<0.05) . The result also showed that progressive aerobic exercise is a suppressor factor to immune system in young and adult athletes, and changes in immune system components of blood in young and adult athletes were similar, except for neutrophils and leukocytes.
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