Acute reduction in spirometry values after prolonged exercise among recreational runners

Abstract

BACKGROUND: Prolonged endurance running may acutely reduce spirometric lung values. This study examined changes in spirometry before and immediately after prolonged endurance exercise (running and/or walking). Specifically, we examined potential factors that predict the presence of at least a 10% postexercise reduction in FEV1. METHODS: After institutional review board approval, recruitment occurred at a pre-race exposition, where informed consent was obtained. Pre-and post-race spirometry measurements were taken from 79 study subjects who competed in a half-marathon (n = 66) or a marathon (n = 13). Spirometry was performed 1–2 days before the marathon or half-marathon and 25 min after finish the race. RESULTS: We identified a subgroup of 23 subjects with a postexercise decrease in FEV1 of ≥10%. In this subgroup, the mean post-race values for FEV1, FVC, and peak expiratory flow were 19–24% lower than the pre-race values. In the 56 subjects with a change in FEV1 of <10%, the mean post-race changes in spirometry values were not >6%. There was no difference between the 2 groups in sex distribution or between subjects who completed the half-marathon or the full marathon. For every 1-y increase in age, the likelihood of developing a postexercise reduction in FEV1 of at least 10% decreased by nearly 10% (R2 = 0.15, P =.003). CONCLUSIONS: Exercise-induced bronchoconstriction (EIB) is the most probable explanation for the reduction in post-race FEV1. Prolonged endurance exercise reduced spirometric lung function by ~20% in those with EIB. Age was the only predictor for EIB, and EIB did not affect the finish times among recreational runners and/or walkers.