Article Title

Estimating Caloric Expenditure using Physical Activity Index (PAI) in Children Performing a Maximal Exercise Test


1Gairola, A., 1Robertson, R., 1Bayles, C., 1Goss, F., 1Kane, I., 1Nagle, E., 2Arslanian, S. 1University of Pittsburgh, Pittsburgh, PA, 2Children’s Hospital, University of Pittsburgh, Pittsburgh, PA.

Purpose: The primary purposes of this investigation were (a) to examine the validity of the PAI, (b) to develop a statistical model to predict cumulative Kcal expenditure using PAI as the predictor variable and (c) to develop a statistical model to predict total Kcal expenditure using PAItotal and selected physiological and behavioral measures as the predictor variables for children and adolescents performing load incremented maximal treadmill exercise. The secondary purpose of the study was to develop a prediction model to estimate total Kcal expenditure using the PAI (session) alone and in combination with selected physiological measures as the predictor variables. Methods: Eighty-four children and adolescents (12.5±2.4yrs) performed a maximal Bruce treadmill (TM) protocol. During TM, heart rate (HR), oxygen consumption (VO2), rating of perceived exertion (RPE-overall), pedometer step count, and Kcal expenditure were measured. Post-TM, RPE-session was obtained and a physical activity questionnaire administered. The PAI, PAItotal, and PAI (session) were calculated as:

PAI = Cumulative step count x RPE-overall

PAItotal = Total step count x RPE-overall at test termination

PAI (session) = Total step count x RPE-session

Results: Multiple regression analyses revealed a strong, positive relation between the PAI score and VO2 in L.min-1(r=0.607, p-1.min-1 (r=0.725, p-1(r=0.755, p

Model I : Cumulative Kcal = 21.632 + 0.006(PAI) p2=0.54.

Model II : Total Kcal = -11.59+0.002(PAItotal)+27.245(VO2max) p2=0.739.

Model V : Total Kcal = 38.6 + 0.004(PAIsession), p2=0.13.

Model VI : Total Kcal = -64.759+26.998(VO2max)+0.305(HRmax)+0.001 (PAIsession) p2 = 0.842.

PAI was a stronger predictor of Kcal expenditure than PAI (session) Conclusions: The PAI has public health implications, provides an easy tool to estimate total physical activity load (i.e. volume x intensity) and predicts Kcal expenditure in children and adolescents performing standard treadmill exercise protocols.

Research funded by NIH RO1 HD027503

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