Aim. The effects of acute exercise on immune system and serum magnesium and iron have been investigated in recent years. However, data related to the comparisons of long-term physical training with different intensity and duration are limited. Methods. The association between long-term physical training and cellular (lymphocyte phenotyping) and humoral immune parameters (serum immunoglobulins) and serum magnesium and iron values in the middle-aged men was investigated. Eleven male master athletes (MA) performing high intensity and long duration training, 11 male recreational athletes (RA) performing moderate intensity and duration training (>10 years) participated. Eleven male sedentary individuals were enrolled as control group (CG). Results. The percentages of total CD3+ T cells, CD4+ T helper, CD8+ T suppressor/cytotoxic, CD19+ B cells, natural killer cells, HLA-DR+ active T cells and CD4/CD8 ratios did not show any significant difference among 3 groups. In MA, VO2max values showed a significant negative correlation with CD4+ T helper cells. There were no significant differences among MA, RA and CG in terms of IgG, IgA, and IgM concentrations. There was a significant correlation between VO2max and IgG in RA. Iron, iron binding capacity and ferritin were found similar in all groups, but serum magnesium level in MA was significantly lower than RA and CG. Conclusion. No exact data to support immunosuppression or immunostimulation could be obtained except a significant negative correlation between CD4+ T helper cells and VO2max values in MA and a positive correlation between serum IgG and VO2max ivalues in RA. These findings may be the indirect markers of cellular immune system suppression by intensive exercises and stimulation of IgG production by moderate exercises
