ABSTRACT
@#Objective To investigate the efficacy of the oxygen uptake efficiency slope (OUES), obtained from submaximal exercise, as an index of cardiopulmonary functional reserve in adults. Methods Exercise tests, following a symptom-limited standard Bruce protocol with simultaneous respiratory gas measurement, were performed on a treadmill in 33 healthy adults free of clinically recognized cardiovascular disease and 31 patients with heart disease. The OUES was derived from the relation between oxygen uptake (VO2) and minute ventilation (VE) during incremental exercise and was determined by VO2=alog10VE+b, where a=OUES. The OUES was calculated from data of the first 75%, 90% and 100% of exercise duration (as 75%OUES，90%OUES and 100%OUES). Results The 100%OUES，90%OUES and 75%OUES were not significantly different from each other（F=0.212，P=0.809）. The 75%OUES was slightly lower (1.9%) than the 100%OUES. The 100%OUES, the 90%OUES and the 75%OUES correlated with the peak VO2 （r=0.836,r=0.824 and r=0.777, P<0.001, respectively）. The VAT correlated with the peak VO2 （r=0.878，P<0.001），and the VE/VCO2 at VAT correlated with the peak VO2 （r=-0.584，P<0.001）. The 100%OUES correlated with the 90%OUES and the 75%OUES （r=0.991 and r =0.945, P<0.001, respectively）. Conclusion The OUES is an index of exercise performance and cardiopulmonary functional reserve on healthy adults and patients with cardiac disease. The 75%OUES from submaximal exercise can be an index of cardiopulmonary functional reserve for patients with cardiac disease.