Estimating Physical Activity in Youth Using a Wrist Accelerometer. Issue 5 (May 2015)

• Record Type: Journal Article
• Authors: CROUTER, SCOTT E.; FLYNN, JENNIFER I.; BASSETT, DAVID R.
• Is Part Of: Medicine and science in sports and exercise. Volume 47:Issue 5(2015)
• Publication Date: 2015-05
• Subjects: Sports medicine -- Periodicals; Exercise -- Physiological aspects -- Periodicals; Exercise -- Health aspects -- Periodicals; 612.044
• DOI: 10.1249/MSS.0000000000000502
• Languages: English
• ISSNs: 0195-9131

Abstract

<abstract> <title>ABSTRACT</title> <sec> <title>Purpose</title> <p>The purpose of this study was to develop and validate methods for analyzing wrist accelerometer data in youth.</p> </sec> <sec> <title>Methods</title> <p>A total of 181 youth (mean ± SD; age, 12.0 ± 1.5 yr) completed 30 min of supine rest and 8 min each of 2 to 7 structured activities, selected from a list of 25. Receiver operating characteristic (ROC) curves and regression analyses were used to develop prediction equations for energy expenditure (child-METs; measured activity V˙O<sub>2</sub> divided by measured resting V˙O<sub>2</sub>) and cut points for computing time spent in sedentary behaviors (SB), light (LPA), moderate (MPA), and vigorous (VPA) physical activity. Both vertical axis (VA) and vector magnitude (VM) counts per 5 s were used for this purpose. The validation study included 42 youth (age, 12.6 ± 0.8 yr) who completed approximately 2 h of unstructured PA. During all measurements, activity data were collected using an ActiGraph GT3X or GT3X+, positioned on the dominant wrist. Oxygen consumption was measured using a Cosmed K4b<sup>2</sup>. Repeated-measures ANOVA were used to compare measured versus predicted child-METs (regression only) and time spent in SB, LPA, MPA, and VPA.</p> </sec> <sec> <title>Results</title> <p>All ROC cut points were similar for area under the curve (≥0.825), sensitivity (≥0.756), and specificity (≥0.634), and they significantly underestimated LPA and overestimated VPA (<italic>P</italic> < 0.05). The VA and VM regression models were within ±0.21 child-METs of mean measured child-METs and ±2.5 min of measured time spent in SB, LPA, MPA, and VPA, respectively (<italic>P</italic> > 0.05).</p> </sec> <sec> <title>Conclusions</title> <p>Compared to measured values, the VA and VM regression models developed on wrist accelerometer data had insignificant mean bias for child-METs and time spent in SB, LPA, MPA, and VPA; however, they had large individual errors.</p> </sec> </abstract>