Energy Expenditure in Obese vs Lean Children at High vs Low Intensity Exercise

Abstract

ACSM uses equations to estimate energy expenditure. These formulas are useful to estimate kilocalories (Kcals) burned for various activities. These formulas are used for applications such as estimating the amount of exercise required for weight loss. PURPOSE: The purpose of this study was to test the accuracy of these formulas at predicting Kcals burned in obese vs lean children in high vs low intensity exercise. METHODS: Healthy children were prospectively recruited. At the first visit a max stress test was completed with a modified Balke protocol. At the 2nd visit, a 90 min exercise challenge was completed at 60% max effort. Oxygen consumption (VO2) & exercise duration were measured. Indexed max VO2 (IMVO2) was obtained during the stress test. ACSM formulas were used to calculate actual vs expected energy expenditure. RESULTS: 27 children (18 Obese, 9 Lean, 13 female, 14 male), mean age 14.7 +/- 3yrs were evaluated. In obese children, estimated energy expenditure (Kcals) was overestimated for high intensity exercise (Table 1), but was underestimated for low intensity exercise (Table 2). For low intensity exercise, obese children also burned more actual Kcals than lean children for the same amount of effort (Table 2). In lean children, there were no differences in ACSM estimated vs actual values. CONCLUSIONS: In obese children, standard formulas used to estimate energy expenditure may be overestimating Kcals required for high intensity exercise, and underestimating Kcals required for low intensity exercise. In addition, during low intensity exercise obese children may burn more Kcals for the same amount of effort as lean children. These findings may be important when structuring exercise programs for weight loss intervention in children.Table 1: High intensity exerciseTable 2: :Low intensity exercise