THE EFFECT OF MAXIMAL EXERCISE ON THE ACTIVITY OF NEUTROPHIL GRANULOCYTES IN HIGHLY TRAINED ATHLETES IN A MODERATE TRAINING PERIOD

Leucocyte cell counts and the phagocytic and chemotactic activities of neutrophil granulocytes were investigated in highly endurance-trained long-distance runners (n = 10) and triathletes (n = 10) during a moderate training period and compared with untrained subjects (n = 10) before and up to 24 h after a graded exercise to exhaustion on a treadmill. After exercise a leucocytosis was noted with a significant increase in lymphocyte (P less-than-or-equal-to 0.01) and neutrophil (P less-than-or-equal-to 0.01) counts in all groups. In neutrophils the number of ingested inert latex beads was significantly increased (P less-than-or-equal-to 0.01) from 0.21 (SD 0.09) to 0.45 (SD 0.22) in controls, from 0.20 (SD 0.12) to 0.56 (SD 0.16) in long-distance runners and from 0.25 (SD 0.08) to 1.03 (SD 0.42) particles per cell in triathletes 24 h after exercise, compared with resting values. The capability of neutrophils to produce microbicidal reactive oxygen species fell (P less-than-or-equal-to 0.05) immediately after exercise in all subjects and then increased by 36 (SD 8) %, 31 (SD 6) % and 19 (SD 9) % in controls, runners and triathletes respectively up to 24 h after exercise (P less-than-or-equal-to 0.05) compared with pre-start values. With respect to the absolute number of neutrophils, ingestion capacity, production of superoxide anions and chemotactic activity, no significant differences were found between athletes and control subjects at rest and after exercise. These data indicate, on the one hand, no impairment of the granulocyte system during a moderate training period in long-distance runners and triathletes but, on the other, that the prolonged activation of the phagocytosis reaction after exercise might impair the granulocyte system in periods of intensive training with high training frequency.