THE TIME-COURSE OF PULMONARY DIFFUSING-CAPACITY FOR CARBON-MONOXIDE FOLLOWING SHORT-DURATION HIGH-INTENSITY EXERCISE

We investigated the time course of changes in post-exercise pulmonary diffusing capacity for carbon monoxide (DLCO), membrane diffusing capa city (DM), and pulmonary capillary blood volume (Vc) in highly trained (HT), moderately trained (MT) and untrained (UT) male subjects (n = 8 /group). Subjects were assigned to groups based on their aerobic capac ity from a preliminary (V) over dot(O2max) test (HT greater than or eq ual to 65, MT = 50-60, UT less than or equal to 50 ml.kg(-1).min(-1)). Resting (BASE) DLCO, DM and VC were obtained, then subjects cycled to fatigue at the highest workrate attained during the preliminary tests . Diffusion measurements were then made at 1, 2, 4, 6 and 24 h. DLCO w as depressed at 1 h, lowest at 6 h and approached BASE values at 24 h in all groups. The DLCO change was paralleled by a change in Vc. Alter ations to Ve were similar between groups except at 24 h where MT and H T subjects had returned to BASE while UT did not. DM was significantly lower than BASE at 1, 2, 4, and 6 h, and was similar between groups. The changes in DLCO post-exercise appear to be primarily due to a decr ease in Vc. Comparable diffusion decrements were observed in all subje cts. The results of this study suggest that post-exercise alterations in DLCO, DM and VC are not related to aerobic capacity. (C) 1998 Elsev ier Science B.V. All rights reserved.