PULMONARY DIFFUSION LIMITATION AFTER PROLONGED STRENUOUS EXERCISE

To determine the effect of strenuous prolonged exericse on alveolo-capillary membrane diffusing capacity, 11 marathon runners aged 37 +/- 7 years (mean +/- SD) were studied before and during early recovery (28 +/- 14 min) from a marathon race. Lung capillary blood volume (Vc) and the alveolo-capillary diffusing capacity (Dm) were determined in a one-step maneuver by simultaneous measurements of CO and NO lung transfer (DL(CO) and DL(NO), respectively) using the single breath, breath-holding method. After the race, both DL(CO) and DL(NO) were significantly decreased in all subjects (-10.9 +/- 4.8%, P < 10(-4) and -29.0 +/- 11.1%, P < 10(-4), respectively). The mean value of the derived Dm(CO) decreased by -29.3 +/- 11.1%, whereas Vc had not entirely returned to control resting value. Although these results do not indicate the detailed mechanism involved, interstitial lung fluid was suspected to accumulate, particularly in alveoli, during the race. We concluded that the high overall work load and the extended duration of the exercise both contributed to a transient change in the structure of the alveolo-capillary membrane thereby affecting the diffusing capacity of the alveolo-capillary membrane.