Acute Reduction in Spirometry Values After Prolonged Exercise Among Recreational Runners

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.

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.

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).

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.