PULMONARY DIFFUSING-CAPACITY AFTER MAXIMAL EXERCISE

To determine the effect of maximal exercise on alveolocapillary membrane diffusing capacity (Dm), 12 professional handball players aged 23.4 +/- 3.3 (SD) yr were studied before and during early recovery from a progressive maximal exercise [immediately (t(0)), 15 min, and 30 min (t(30)) after exercise]. Lung capillary blood volume and Dm were determined in a one-step maneuver by simultaneous measurement of CO and NO lung transfer (DL(CO) and DL(NO) respectively) with use of the single-breath breath-hold method. At t(0) DL(CO) was elevated (13.1 +/- 12.0%; P < 0.01) but both DL(NO) and Dm for CO remained unchanged. Between t(0) and t(30), both DL(CO) and DL(NO) decreased significantly. At t(30), DL(CO) was not different from the control resting value. DL(NO) (and consequently Dm for CO) was significantly lower than the control value at t(30) (-8.9 +/- 8.1%; P < 0.01). Lung capillary blood volume was elevated at t(0) (18.0 +/- 19.0%; P < 0.01) but progressively decreased to near control resting values at t(30). Differences in the postexercise kinetics of both DL(CO) and DL(NO) point to a role of the transient increase in pulmonary vascular recruitment during the recovery period. We concluded that Dm was somewhat decreased in the 30 min after maximal exercise of short duration, but the exact pulmonary mechanisms involved remain to be elucidated.