INTRODUCTION: Prolonged strenuous exercise has been associated with a transient depression of immune function, with prolonged intense training schedules and competition able to lead to immune impairment in athletes. OBJETIVE: The objective of this study was to see if chronic training was able to produce sustained differences in the peripheral blood (PB) leukocyte subpopulations (WBC, granulocytes, monocytes, total lymphocytes, B and T lymphocytes, CD4+ and CD8+ T cells and Natural Killer cells) of elite kayakers when compared to non-athletes. METHODS: The sample comprised 13 elite male kayakers, 20 ± 3 years old, 75.0 kg ±7.9 weight and 177.3±7.1 cm stature. The VO2max was 58.3±7.8 mL.kg.min-1. The Non-athlete group comprised 7 health males, aged 18±1 years old, 81.3±13.8 kg of weight and 171.9±4.5cm stature. The athlete's blood samples were collected at the beginning of the training season, after an off period of six weeks of training. Peripheral blood cell populations were identified by flow cytometry analysis. To verify the differences between the athlete and non-athlete groups the Mann-Whitney U Test was used. RESULTS: No differences between the trained kayakers and the non-athletes were found at rest except for Natural Killer cells (CD3-CD56+) and the CD3-CD56+CD8+ subset values that were lower in the athletes. CONCLUSION: Our study found that after a prolonged time without training (six weeks) only the NK CD3-CD56+ population and particularly the highly cytotoxic CD3-CD56+CD8+ subpopulation had lower levels in the elite athletes when compared to the untrained men.
athletes; natural killer cells; lymphocytes; T-lymphocytes; immunology