Immune and oxidative changes during and following the Western States Endurance Run

Changes in immune and oxidative stress parameters were measured in ultramarathon runners competing in the 160-km Western States Endurance Run. Forty-five runners agreed to provide blood and saliva samples the morning before the race event, at the 90-km aid station, and 5-10 min post-race. Upper respiratory tract infection (URTI) during the two-week period post-race was assessed retrospectively by telephone interviews. Forty subjects completed 90-km (race time, 13.1 ± 0.3 h), and 31 completed the 160-km race event (27.0 ± 0.4 h). The blood neutrophil and monocyte counts rose 249% and 214%, respectively, in the 31 finishers. Salivary IgA (sIgA) secretion rate decreased significantly from 508 ± 40 μg/min pre-race, to 287 ± 39 μg/min at 90-km, and 254 ± 30 μg/min post-race (50% decrease). Significant increases were measured in cytokines at 90-km and post-race, with post-race IL-10 increasing 9.5-fold, IL-1ra 6.1-fold, IL-6 50.2-fold, and IL-8 2.5-fold over pre-race levels. Post-race indicators of oxidative stress, F₂-isoprostane and lipid hydroperoxides, increased 33% and 88%, respectively. Pearson product-moment correlations revealed positive correlations at 90-km between F₂-isoprostane and IL-6 (r=0.31, p=0.048), IL-10 (r=0.31, p=0.050), and IL-8 (r=0.43, p=0.005), but no other significant relationships between immune and oxidative stress indicators at 90-km and post-race. In the group of runners completing at least 90 km of the race, 26% reported an URTI episode during the two-week period post-race. A low sIgA secretion rate at 90-km was the best predictor of post-race URTI (173±34 μg/min in those who later acquired URTI compared to 325±40 μg/min in those without URTI, p=0.007). In conclusion, a modest correlation was found between cytokines and F₂-isoprostane at 90-km when the greatest oxidative stress occurred, but no other significant correlations in immune and oxidative stress indicators during and following a 160-km ultramarathon race event were noted. About one in four ultramarathoners reported URTI during the two-week period post-race, and a low sIgA secretion rate mid-race best predicted URTI occurrence.