Pedro F Saint-Maurice1,2, Youngwon Kim3,4, Gregory J Welk5, Glenn A Gaesser6. 1. Department of Kinesiology, Iowa State University, 235 Forker Building, Ames, IA, 50011, USA. pedrosm@iastate.edu. 2. School of Psychology: CIPsi, University of Minho, Braga, Portugal. pedrosm@iastate.edu. 3. Department of Kinesiology, Iowa State University, 235 Forker Building, Ames, IA, 50011, USA. youngwon.kim@mrc-epid.cam.ac.uk. 4. MRC Epidemiology Unit, School of Clinical Medicine, University of Cambridge, Cambridge, CB2 0QQ, UK. youngwon.kim@mrc-epid.cam.ac.uk. 5. Department of Kinesiology, Iowa State University, 235 Forker Building, Ames, IA, 50011, USA. gwelk@iastate.edu. 6. School of Nutrition and Health Promotion, Arizona State University, 550 N Third St, Phoenix, AZ, 85004, USA. glenn.gaesser@asu.edu.
Abstract
PURPOSE: The study compares MET-defined cutpoints used to classify sedentary behaviors in children using a simulated free-living design. METHODS: A sample of 102 children (54 boys and 48 girls; 7-13 years) completed a set of 12 activities (randomly selected from a pool of 24 activities) in a random order. Activities were predetermined and ranged from sedentary to vigorous intensities. Participant's energy expenditure was measured using a portable indirect calorimetry system, Oxycon mobile. Measured minute-by-minute VO2 values (i.e., ml/kg/min) were converted to an adult- or child-MET value using the standard 3.5 ml/kg/min or the estimated child resting metabolic rate, respectively. Classification agreement was examined for both the "standard" (1.5 adult-METs) and an "adjusted" (2.0 adult-METs) MET-derived threshold for classifying sedentary behavior. Alternatively, we also tested the classification accuracy of a 1.5 child-MET threshold. Classification accuracy of sedentary activities was evaluated relative to the predetermined intensity categorization using receiver operator characteristic curves. RESULTS: There were clear improvements in the classification accuracy for sedentary activities when a threshold of 2.0 adult-METs was used instead of 1.5 METs (Se1.5 METs = 4.7%, Sp1.5 METs = 100.0%; Se2.0 METs = 36.9%, Sp2.0 METs = 100.0 %). The use of child-METs while maintaining the 1.5 threshold also resulted in improvements in classification (Se = 45.1%, Sp = 100.0%). CONCLUSION: Adult-MET thresholds are not appropriate for children when classifying sedentary activities. Classification accuracy for identifying sedentary activities was improved when either an adult-MET of 2.0 or a child-MET of 1.5 was used.
PURPOSE: The study compares MET-defined cutpoints used to classify sedentary behaviors in children using a simulated free-living design. METHODS: A sample of 102 children (54 boys and 48 girls; 7-13 years) completed a set of 12 activities (randomly selected from a pool of 24 activities) in a random order. Activities were predetermined and ranged from sedentary to vigorous intensities. Participant's energy expenditure was measured using a portable indirect calorimetry system, Oxycon mobile. Measured minute-by-minute VO2 values (i.e., ml/kg/min) were converted to an adult- or child-MET value using the standard 3.5 ml/kg/min or the estimated child resting metabolic rate, respectively. Classification agreement was examined for both the "standard" (1.5 adult-METs) and an "adjusted" (2.0 adult-METs) MET-derived threshold for classifying sedentary behavior. Alternatively, we also tested the classification accuracy of a 1.5 child-MET threshold. Classification accuracy of sedentary activities was evaluated relative to the predetermined intensity categorization using receiver operator characteristic curves. RESULTS: There were clear improvements in the classification accuracy for sedentary activities when a threshold of 2.0 adult-METs was used instead of 1.5 METs (Se1.5 METs = 4.7%, Sp1.5 METs = 100.0%; Se2.0 METs = 36.9%, Sp2.0 METs = 100.0 %). The use of child-METs while maintaining the 1.5 threshold also resulted in improvements in classification (Se = 45.1%, Sp = 100.0%). CONCLUSION: Adult-MET thresholds are not appropriate for children when classifying sedentary activities. Classification accuracy for identifying sedentary activities was improved when either an adult-MET of 2.0 or a child-MET of 1.5 was used.
Entities:
Keywords:
Measurement; Public health; Resting energy expenditure; Youth
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