Abstract
Anatomical R-L shunt at rest and the pulmonary diffusing capacity during near-maximal exercise were studied in 9 boys aged 11 to 13 years before and after a 16-week period of systematic physical training. Physical training resulted in a significant decrease of resting anatomical R–L shunt from 4.6 to 2.9 per cent of cardiac output, corresponding to a Pao2 of 607 and 635 mm Hg during oxygen breathing respectively. Physical training failed to induce any change in exercise DLCO despite a significant increase of cardiac output and ventilation.