Race in a hot environment changes the leukocyte profile in healthy trained subjects

Abstract

Aims: To assess the effects of an outdoor race of 15 km in a hot environment on leukocyte kinetics in healthy trained men.

Methods: The sample consisted of 14 men who participated in a recreational race group. Volunteers who said they were able to run a minimum distance of 15 km, were not taking any immunosuppressants, and had no infectious disease were included in the study. The exclusion criteria were the following: hypertension at rest before the race, history of musculoskeletal, metabolic and/or cardiovascular diseases, and failure to finish the race. Venous blood samples were collected before and after the race for determination of hematocrit levels and immune cell count by immunocytochemistry.

Results: An increase in total leukocyte and neutrophil count was observed after the race (9.31±2.4 x 10³ cells/µL and 7.64±3.4 x 10³ cells/µL, respectively) compared to the pre-race period (5.52±0.2 x 10³ cells/µL and 2.90±0.6 x 10³ cells/µL, respectively), (p<0.05). There was a decrease in lymphocyte and eosinophil count after the race (1.34±0.3x10³ and 0.36±0.2x10³ cells/µL, respectively) compared to the pre-race period (1.67±0.3x10³ and 0.22±0.1x10³ cells/µL, respectively) (p<0.05). There was no statistically significant difference in monocyte and basophil count after the race (0.45±0.1x10³ and 0.9±0.3x10³ cells/µL, respectively) compared to the pre-race period (0.40±0.08x10³ and 0.8±0.3x10³ cells/µL, respectively) (p>0.05).

Conclusions: The 15-km outdoor race in a hot environment led to a typical leukocyte kinetics, resulting in leukocytosis owing to the increase in neutrophil count as well as to a decrease in lymphocyte and eosinophil count in healthy trained men. These findings shed some further light upon exercise-induced leukocytosis and may indicate the level of stress produced by exercise under extreme environmental conditions.