Reproducibility of the oxygen uptake efficiency slope in normal healthy subjects

Background. To elucidate the intertest agreement of the oxygen uptake effic iency slope (OUES) in comparison with those of the maximal oxygen uptake (( V) over dot O(2)max) and the ventilatory anaerobic threshold (VAT). Methods. Experimental design: A comparative study. Setting: Institutional p ractice. A total of 19 healthy volunteers underwent two sessions of maximal exercise testing with an interval of no more than 7 days. The testing was conducted on a cycle ergometer with the work rate increased by either 20, 3 0 or 40 Watts (W)/min so that the subject would reach exhaustion within 9 t o 12 min of exercise, VAT was defined as the level of oxygen uptake ((V) ov er dot O-2) at which either an increase in the ventilatory equivalent for o xygen without a concomitant increase in the ventilatory equivalent for carb on dioxide or a change in the slope of the linear relationship between carb on-dioxide production ((V) over dot CO2) and (V) over dot O-2 occurred. OUE S was determined by the following equation: (V) over dot O-2=a log (V) over dot E+b, where (V) over dot E was minute ventilation and "a" was the OUES, Intertest reproducibility was assessed by coefficient of repeatability (CO R), Results. The intertest reproducibility of (V) over dot O(2)max and OUES wer e excellent (COR=570 ml/min [16%] and 740 [20%], respectively). VAT showed poor agreement between the two tests (COR=650 ml/min [31%]), Conclusions. Results show that OUES is reproducible and reliable, supportin g the clinical usefulness of this index.