University of Worcester Worcester Research and Publications

Intra‐ and Inter‐Instrument Reliability of the Actiwatch 4 Accelerometer in a Mechanical Laboratory Setting

Routen, Ashley, Upton, Dominic, Edwards, M.G. and Peters, D.M. (2012) Intra‐ and Inter‐Instrument Reliability of the Actiwatch 4 Accelerometer in a Mechanical Laboratory Setting. Journal of Human Kinetics, 31. pp. 17-24. ISSN 1640-5544 (print version) 1899-7562 (electronic version)

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This study aimed to quantify the intra�]and inter�]instrument reliability of the Actiwatch 4 accelerometer (AW4) in a mechanical setting. Twenty seven AW4 were attached to an isokinetic dynamometer and subjected to angular acceleration for 30 min at 50 deg/sec representing moderate intensity (MPA condition) and 200 deg/sec representing vigorous intensity (VPA condition), with a repeat trial conducted. Reliability was assessed using coefficient of variation (CV), absolute percent error (APE), and intraclass correlation coefficients (ICC). Mean AW4 activity counts displayed acceptable reliability according to CV in both conditions (ConMPA: CVintra = 4.6%, APEintra = 6.6%, CVinter = 6.4%, APEinter = 5.2%; ConVPA: CVintra = 3.9%, APEintra = 5.6%, CVinter = 5.9%, APEinter = 4.7%). When counts were re�]categorised into minutes of MPA and VPA, lower CV values were observed (ConMPA: CVintra = 3.2%, APEintra = 4.5%, CVinter = 4.3%, APEinter = 3.2%; ConVPA: CVintra = 0.0%, APEintra = 0.0%, CVinter = 0.0%, APEinter = 0.0%). When activity counts were re�]categorised as minutes of MVPA, excellent reliability was observed (CVintra, APEintra, CVinter, and APEinter = 0.0%) in both conditions. Mean AW4 activity counts exhibit reliability statistics comparable to other accelerometers. Reliability is improved when activity counts are re�]categorised as time spent in MPA and VPA, with greatest reliability obtained when counts are recategorised as time spent in MVPA. As MVPA is the subcomponent of physical activity most associated with health benefits it would appear that the AW4 is reliable for measuring time spent in this health enhancing intensity category,at least from testing in a mechanical laboratory setting.

Item Type: Article
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Uncontrolled Keywords: physical activity, activity monitor, measurement, repeatability, accelerometer
Subjects: R Medicine > RC Internal medicine > RC1200 Sports Medicine
Divisions: Academic Departments > Institute of Sport and Exercise Science
Depositing User: Ashley Routen
Date Deposited: 23 Mar 2012 09:52
Last Modified: 03 Aug 2015 14:34

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