The purpose of this study was to determine the effect of six months moderate aerobic training on the immune system of aged men using VO2max as indicator and some selective markers of immune system. 40 healthy aged males (60-70 years) were selected and randomly divided into two groups: experimental and control. Before the experiment measurements on VO2max, counts of CD4 and CD8 cells of all subjects were taken. Afterward the experimental group performed moderate aerobic training three times a week for 6 months (the first 3 months with intensity 35- 45% Heart rate reserve and duration of 20-30 minutes and the second 3 months with 45-60% Heart rate reserve and duration of 30-40 minutes). The control group did not do any regular training exercises. The same variables were measured after 3 months (Mid-experiment) and 6 months (post-experiment) for all subjects. Statistical analyses used were ANOVA and student’s t test. Moderate aerobic exercises increased VO2max significantly (19/5%) in the experimental group as compared to the control group and also between pre-, mid experiment phases with post-experiment phase of test group (P<%5). The number of CD4 and CD8 cells in the training group had increased significantly as compared to the control group and CD4/CD8 ratio in training group was significantly lower than the control group (the rate 8%)(P<%5). The results confirmed that moderate aerobic exercise may increase VO2max and improve immunity system markers in aged men.
