부산대학교 도서관

OBJECTIVE:Cardiorespiratory fitness is currently estimated by dividing maximal oxygen consumption (VO2max) by body weight (per-weight standard). However, the statistically correct way to neutralize the effect of weight on VO2max in a given population is adjustment for body weight by regression techniques (adjusted standard). Our objective is to quantify the bias introduced by the per-weight standard in a population distributed across different categories of body mass.DESIGN:This is a cross-sectional study.SUBJECTS AND METHODS:Baseline measures from participants of the Dose-Responses to Exercise Training Study (DR's EXTRA), 635 men (body mass index (BMI): 19-47 kg m−2) and 638 women (BMI: 16-49 kg m−2) aged 57-78 years who performed oral glucose tolerance tests and maximal exercise stress tests with direct measurement of VO2max. We compare the increase in VO2max implied by the per-weight standard with the real increase of VO2max per kg body weight. A linear logistic regression model estimates odds for abnormal glucose metabolism (either impaired fasting glycemia or impaired glucose tolerance or Type 2 diabetes) of the least-fit versus most-fit quartile according to both per-weight standard and adjusted standard.RESULTS:The per-weight standard implies an increase of VO2max with 20.9 ml min−1 in women and 26.4 ml min−1 in men per additional kg body weight. The true increase per kg is only 7.0 ml min−1 (95% confidence interval: 5.3-8.8) and 8.0 ml min−1 (95% confidence interval: 5.3-10.7), respectively. Risk for abnormal glucose metabolism in the least-fit quartile of the population is overestimated by 52% if the per-weight standard is used.CONCLUSIONS:In comparisons across different categories of body mass, the per-weight standard systematically underestimates cardiorespiratory fitness in obese subjects. Use of the per-weight standard markedly inflates associations between poor fitness and co-morbidities of obesity. [ABSTRACT FROM AUTHOR]