A competitive marathon race decreases neutrophil functions in athletes.

A full marathon is the longest running race in official track events and is a form of acute exercise. However, no studies have examined the acute neutrophil function response to a competitive marathon race. Thirty-six male athletes who had just completed the 42.195 km course of the 50th Beppu-Oita Mainichi Marathon were enrolled in this study. Neutrophil oxidative burst activity, phagocytic activity and expression of CD11b and CD16 per cell were measured by flow cytometry immediately before and after the marathon. Total leukocyte/neutrophil counts increased significantly (p < 0.001), whereas total oxidative burst activity per neutrophil cell decreased significantly after the race (p < 0.001). Furthermore, total phagocytic activity per neutrophil cell also decreased after the race, although it was not significant (p = 0.08). Although CD11b expression per cell did not change, the expression of CD16 per cell significantly decreased (p < 0.001) after the race. In conclusion, a competitive marathon race decreased neutrophil functions (oxidative burst activity and phagocytic activity), which may be partly due to a decrease in CD16 expression. The increase in total neutrophil counts might reflect a compensatory response to counteract the decrease in neutrophil functions.