INFLUENCE OF EXERCISE INTENSITY AND DURATION ON POSTEXERCISE PULMONARY DIFFUSION CAPACITY

Pulmonary diffusion capacity has been observed to be reduced by approx imately 14% 2 h after 4-6 min of maximal exercise. The purpose of this study was to determine if the decrease in pulmonary diffusion capacit y also occurs when the duration of exercise intensity is shorter or wh en the exercise intensity is lower. We measured pulmonary diffusion ca pacity using the single breath method in 12 competitive rowers 22 (16- 31) years old, 70 (56-100) kg body weight, and 180 (171-193) cm body h eight under two conditions: (1) 2 h after 6 min of rowing at both 61% (58%-68%) and 76% (73%-78%) of maximal oxygen uptake; (2) 2 h after 1, 2, or 3 min of all-out rowing. Values are presented as medians with r anges. Pulmonary diffusion capacity was reduced by 6% (2%-17%) after 6 min of rowing at 61% and by 10% (-7%-21%) after 6 min of rowing at 76 % of maximal oxygen uptake (p < 0.03). Pulmonary diffusion capacity wa s reduced by 7% (3%-19%), 8% (2%-17%) and 7% (1%-16%) after 1, 2, and 3 min of all-out rowing (p<0.01). We conclude that submaximal exercise at 61% of maximal oxygen uptake will affect pulmonary diffusion capac ity following exercise as will shorter duration of maximal exercise. A lthough the mechanism for this fall in pulmonary diffusion capacity is unclear, the fact that it occurs after even mild exercise makes a sig nificant change in pulmonary capillary membrane integrity or sub-clini cal pulmonary edema unlikely. Rather, we suggest that a fall in centra l blood volume might explain the decrease in pulmonary diffusion capac ity following exercise.