Effects of summer camp endurance training on non-specific immunity in long-distance runners

The present study was conducted to investigate the effects of endurance training during a 1-month summer camp on the non-specific host defence systems of ten highly trained male long-distance runners. Examinations with informed consent were carried out three times: 2 days before the training began, an intermediate day, and 2 days after the camp. The subjects ran a total of about 800 km during the camp. Neutrophilic reactive oxygen species (ROS) generation determined by luminol- and lucigenin-dependent chemiluminescence and cytochrome c reduction methods was assayed at two time points because the camp was held far from our laboratory: neutrophils isolated 6 hours after blood sampling were examined at all three time points and neutrophils isolated immediately after blood sampling were examined before and after the camp. The ROS production indicated by peak height of luminol-dependent chemiluminescence and peak velocity of cytochrome c reduction from neutrophils isolated 6 hours after blood sampling was suppressed after the camp (P < 0.05 for both), but, the ROS production from neutrophils isolated immediately after blood sampling and the serum opsonic activity appeared not to be affected. Neutrophils diminished their activity during the 6-hour waiting time after the camp. These results suggest that the non-specific host defence system is not directly impaired by long, strenuous endurance training.