Oxygen Uptake Efficiency Slope (oues)

Abstract

VO2max obtained by a maximal effort is historically an important predictor of endurance performance. However, exercise testing protocol and subjective factors affect the measurement of this value, which is seldom attained. The oxygen uptake efficiency slope (OUES), which relates oxygen uptake to total ventilation during exercise, was proposed as alternative submaximal index of cardiorespiratory functional reserve in pediatric cardiac patients. No previous studies have investigated if OUES could be a good predictor also in highly trained athletes. PURPOSE: Our objective was to investigate OUES in comparison with VO2max in triathletes and its correlation to performance. METHODS: 13 high level young triathletes free of clinically recognized cardiovascular disease (7 males, 6 females, respectively age 18.1±0.90 and 16.8±0.98 years; height 179.6±6.4 and 162.8±2.64 cm; weight 65.0±3.53 and 53.5±4.2 kg) participated to the study. After giving written informed consent, they performed a treadmill exhaustive incremental test to determine their OUES that was calculated from data taken from the first 75%, 90% and 100% of the exercise duration in those subjects who were considered to have achieved a maximal effort. OUES was used to correlate either VO2max or 10 km running performance took a week later. Differences in the mean values were analyzed by the analysis of variance (ANOVA). The correlations between VO2max, OUES and running performance were assessed by linear regression analysis. RESULTS: VO2max resulted highly correlated either to OUES 75 (r 0.91) or OUES 90 (r 0.93) or OUES 100 (r 0.92) p<0.05. Also the running time performance was correlated to OUES either to OUES 75 (r 0.89) or OUES 90 (r 0.91) or OUES 100 (r 0.88) p<0.05. Finally, the running time performance was correlated to VO2max (r -0.98) p<0.05. CONCLUSION: The main findings of this study indicate that OUES in triathletes is independent of exercise intensity, that OUES 75 and OUES 90 are valid to determine VO2peak without achieving the maximal efforts and that it shows a valid correlation with running performance, as the VO2max. Results confirm that OUES is reproducible and reliable, supporting its validity to estimate the fitness state of athlete.