Effects of maximal exercise on nonspecific immunity in athletes under trained and detrained conditions

We investigated both the acute effects of maximal exercise and the chronic effects of training on nonspecific immunity in 15 winter-sports athletes during different periods of training: (a) before the athletic season, in summer, when the athletes were undertaking extensive endurance training to enhance aerobic capacity, (b) during the winter sports season, in early winter, when endurance and athletic training were being undertaken, and (c) after the winter sports season, in spring, when the athletes were resting (detraining for a month). The mean value of the maximal oxygen uptake in each training period was (a) 65.4 (SD 4.6) mL·kg^-1·min^-1, (b) 63.1 (SD 5.5) mL·kg^-1·min^-1, and (c) 58.3 (SD5.8) mL·kg^-1·min^-1. respectively. Following maximal exercise, acute peripheral leukocytosis due to lymphocytosis and neutrophila was observed in every period. The capacity of isolated neutrophils to produce reactive oxygen species upon stimulation with opsonized zymosan measure by luminol-dependent chemiluminescence (LDCL) was significantly enhanced after maximal exercise before and during the athletic season. However, the degree of enhancement was smaller during after-season detraining, suggesting that the conditioning state affected the exercise-induced changes in neutophil functional status. Serum opsonic activity also showed a similar pattern. As for the chronic effects of training, the resting values of the neutrophil count, especially the segmented neutrophil count, the neutrophil LDCL response and the serum IgG level, declined significantly in the pre-season training period. Since the subjects were engaged in exhaustive endurance training under heat exposure at that time, the nonspecific immune status might have been partially compromised due to chronic overload.