Changes in pulmonary diffusing capacity and closing volume after running a marathon

The purpose of this study was to evaluate changes in lung function after running a marathon. Pulmonary function tests were administered to 8 men before, immediately after, and the day following competition X ̄ run time = 3 hr 30 min). Subjects completed maximum expiratory flow volume maneurvers breathing air and 80% He/20% O₂. Lung volumes were determined by N₂ washout and single breath He dilution. Closing volumes (CV) were determined using a single breath O₂ test. Pulmonary diffusing capacity (DL_CO), pulmonary capillary blood volume (Vc), and membrane diffusing capacity (DM) were measured with the single breath technique. There were no changes in lung volumes or flow rates, except for an increase in FEV₁, after the marathon. The He/O₂ ΔV̇max₅₀, ΔV̇max₂₅, and isoflow values were similar pre- compared to post-race. There were significant decreases, however, in DL_CO, DM and increases in CV prost-race. Vc remained similar to pre-race values. These results suggest that small airways obstruction does not occur after a marathon. The significant increase in alveolarcapillary membrane resistance, however, may reflect the occurence of subclinical edema. Such a change would decrease lung elastic recoil and could explain the increase in CV.