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Impact of methodological decisions on accelerometer outcome variables for physical activity and sedentary behaviour in young children

Ojiambo, R and Cuthill, R. and Budd, H. and Konstabel, K and Casajus, J.A. and Gonzalez-Aguero, A. and Arjila, E. and Reilly, John J and Easton, C and Pitsiladis, Y.P (2011) Impact of methodological decisions on accelerometer outcome variables for physical activity and sedentary behaviour in young children. International Journal of Obesity, 35 (1). pp. 98-103. ISSN 0307-0565

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Abstract

The impact of accelerometer-related methodological decisions relating to the assessment of physical activity and sedentary time has not been conclusively determined in young children. To determine the effects of epoch and cutoff points on the assessment of physical activity and sedentary time and to determine the accelerometer wear time required to achieve reliable accelerometer data in children. Children were recruited from centres at Ghent, Glasgow, Gothenburg and Zaragoza. Physical activity was assessed for 1 week in 86 children (41 girls, 45 boys; mean age 7±2 years) by uniaxial accelerometry. The epoch was set at 15 s and reintegrated to 30 and 60 s. Time spent sedentary and in moderate and vigorous physical activity (MVPA) was assessed using a range of cutoff points. Number of days required to achieve 80% reliability was predicted using the Spearman-Brown Prophecy formula. The Reilly cutoff points (<1100 counts per min (CPM)) indicated less sedentary time per day when comparing 15 vs 30 s and 15 vs 60 s epochs: 570±91 vs 579±93 min and 570±91 vs 579±94 min, respectively; P<0.05. Pate cutoff points (>420 counts per 15 s) reported more MVPA time per day compared with Sirard (890 counts per 15 s) and Puyau cutoff points (>3200 counts per min) using 15 s epoch: 78 (4-197) min (median (range) vs 18 (1-80) min and 24 (1-100) min, respectively; P<0.001. Compliance with guidelines of at least 60 min MVPA was 84, 78 and 73% for Pate cutoff points using 15, 30 and 60 s epochs, respectively, but 0% for Sirard and Puyau cutoff points across epochs. The number of days required to achieve 80% reliability for CPM, sedentary and MVPA time was 7.4-8.5 days. Choice of epoch and cutoff point significantly influenced the classification of sedentary and MVPA time and observed compliance to the MVPA guidelines.

Item type: Article
ID code: 32171
Keywords: obesity , obesity prevention, child health, physical activity, Child Health. Child health services, Personal health and hygiene, including exercise, nutrition , Endocrinology, Diabetes and Metabolism, Medicine (miscellaneous), Nutrition and Dietetics
Subjects: Medicine > Pediatrics > Child Health. Child health services
Medicine > Public aspects of medicine > Personal health and hygiene, including exercise, nutrition
Department: Faculty of Humanities and Social Sciences (HaSS) > School of Psychological Science and Health > Physical Activity for Health
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Depositing user: Pure Administrator
Date Deposited: 13 Jul 2011 10:57
Last modified: 05 Sep 2014 09:57
URI: http://strathprints.strath.ac.uk/id/eprint/32171

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