Activity related energy expenditure in children and adolescents with Prader-Willi syndrome

OBJECTIVE: To measure activity related energy expenditure in Prader-Willi s yndrome (PWS) corrected for body size. SUBJECTS: 17 PWS subjects (10 females, seven males, age 7.5-19.8 y) and 17 obese controls, matched for gender and bone age. MEASUREMENTS: Basal metabolic rate (BMR) was measured by ventilated hood an d average daily metabolic rate (ADMR) was measured with doubly labelled wat er. Activity induced energy expenditure (AEE) was calculated as 0.9ADMR - B MR. Activity related energy expenditure was corrected for body size using t he following measures: AEE per kg body weight (AEE/kg), ADMR/BMR (PAL), and the residual of the regression of ADMR on BMR (rADMR). Group differences w ere analyzed by analysis of covariance adjusting for bone age, fat mass (FM ) and gender. RESULTS: ADMR, AEE and PAL were lower (P < 0.01) in the PWS group compared with the control group (7.14 +/- 1.72, 1.07 +/- 0.69 and 1.33 +/- 0.15 MJ/d ay compared with 9.94 +/- 2.64, 2.56 +/- 1.03 and 1.55 +/- 0.12 MJ/day resp ectively). The variance of AEE/kg and PAL was significantly explained by ge nder and PWS, while AEE was additionally explained by FM. The variance of r ADMR was explained by PWS and not by FM or gender CONCLUSION: Activity related energy expenditure is decreased in PWS compare d with controls adjusted for bone age, FM and gender.