title: Comparison of children's free-living physical activity derived from wrist and hip raw accelerations during the segmented week.
abstract: This study assessed children's physical activity (PA) levels derived from wrist-worn GENEActiv and hip-worn ActiGraph GT3X+ accelerometers and examined the comparability of PA levels between the two devices throughout the segmented week. One hundred and twenty-nine 9-10-year-old children (79 girls) wore a GENEActiv (GAwrist) and ActiGraph GT3X+ (AGhip) accelerometer on the left wrist and right hip, respectively, for 7 days. Mean minutes of light PA (LPA) and moderate-to-vigorous PA (MVPA) per weekday (whole-day, before-school, school and after-school) and weekend day (whole-day, morning and afternoon-evening) segments were calculated, and expressed as percentage of segment time. Repeated measures analysis of variance examined differences in LPA and MVPA between GAwrist and AGhip for each time segment. Bland-Altman plots assessed between-device agreement for LPA and MVPA for whole weekday and whole weekend day segments. Correlations between GAwrist and AGhip were weak for LPA (r = 0.18-0.28), but strong for MVPA (r = 0.80-0.86). LPA and MVPA levels during all weekday and weekend day segments were significantly higher for GAwrist than AGhip (p < 0.001). The largest inter-device percent difference of 26% was observed in LPA during the school day segment. Our data suggest that correction factors are needed to improve raw PA level comparability between GAwrist and AGhip.
authors.affiliation: a Physical Activity Exchange, Research Institute for Sport and Exercise Sciences , Liverpool John Moores University , Liverpool , UK.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Noonan
authors.affiliation: a Physical Activity Exchange, Research Institute for Sport and Exercise Sciences , Liverpool John Moores University , Liverpool , UK.
authors.forename: Lynne M
authors.initials: LM
authors.lastname: Boddy
authors.affiliation: b MRC Epidemiology Unit , University of Cambridge School of Clinical Medicine , Cambridge , UK.
authors.forename: Youngwon
authors.initials: Y
authors.lastname: Kim
authors.affiliation: a Physical Activity Exchange, Research Institute for Sport and Exercise Sciences , Liverpool John Moores University , Liverpool , UK.
authors.forename: Zoe R
authors.initials: ZR
authors.lastname: Knowles
authors.affiliation: c Department of Sport and Physical Activity , Edge Hill University , Ormskirk , UK.|d Department of Physical Education and Sport Sciences , University of Limerick , Limerick , Ireland.
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Fairclough
mesh_terms: D061725:Accelerometry / Q000295:instrumentation* / Q000379:methods*; D002648:Child; D015444:Exercise; D005260:Female; D006615:Hip; D006801:Humans; D008297:Male; D013997:Time Factors; D014953:Wrist
keywords: ActiGraph GT3X+; GENEActiv; Physical activity; children; raw accelerations