Prediction of Oxygen Uptake and Energy Expenditure During Exercise in Obese Women

摘要

PurposeFor patients concerned with weight loss, monitoring the energy balance between daily dietary intake and exercise expenditure can be useful. Formulas commonly used to estimate the energy costs of exercise were previously derived from healthy men of normal body weight. The purpose of this study was to determine the relationship between measured and predicted exercise energy expenditure for obese women.MethodsOxygen uptake (˙VO2) was measured using respiratory gas analysis in 45 obese (92±16 kg; 40±7% fat) and 10 normal weight (control) (58±5 kg; 21±6% fat) women during progressive exercise on a motorized treadmill. ˙VO2was also calculated at matched workrates using a regression equation published by the American College of Sports Medicine. The relationship between predicted versus measured ˙VO2was determined using least squares regression analysis.ResultsThe slope of the regression line for measured versus predicted ˙VO2for controls (y=0.98x±0.56; P.001) was different than that of obese women (y=0.75x±3.06; P.001). The slope of the regression line for controls was in close approximation to the line of identity, whereas the slope for obese was below it. Using ˙VO2to calculate kcal, measured energy expenditure, was significantly lower than predicted energy expenditure for obese subjects, but not for controls at several matched workrates: Stage III (213±40 versus 225±38 kcal per 30 minutes, P.001); stage 4 (292±55 versus 340±58 kcal per 30 minutes, P.001); and stage 5 (330±55 versus 412±70 kcal per 30 minutes, P.001) obese measured versus obese predicted, respectively.ConclusionsThe authors conclude that the standard prediction equation gives a better estimation of ˙VO2for women who have average body weight and body fat than for obese women. This may, in part, be due to the differences in weight and/or fat mass between these subjects and those used to derive this equation. These findings should be considered when estimates of ˙VO2and energy expenditure are used rather than direct measures for obese women.