Possible in vivo tolerance of human polymorphonuclear neutrophil to low-grade exercise-induced endotoxaemia

To address the question of whether translocation of bacterial lipopolysacch aride (LPS) into the blood could be involved in the process of exercise-ind uced polymorphonuclear neutrophil (PMN) activation, 12 healthy male subject s who took part in at sprint triathlon (1.5 km river swim, 40 km bicycle ra ce, 10 km road race) were studied. While there was no detectable amount of endotoxin in the blood samples drawn at rest, exercise was followed by the appearance of circulating endotoxin molecules at the end of competition in four subjects, and after one and 24 h recovery in three and seven athletes, respectively. The concentrations of plasma granulocyte myeloperoxidase ([M PO]), were significantly higher immediately after exercise and one hour lat er than baseline values (P<0.001). This variable returned to pre-race level s the day after exercise, despite the presence of detectable amounts of LPS , at that time, in seven athletes. The absence of significant correlation ( r=0.26; P=0.383) and temporal association between [MPO] and plasma endotoxi n levels led us to conclude that endotoxaemia was not Involved in the proce ss of exercise induced PMN degranulation observed in our subjects.