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Differentiating sitting and lying using a thigh-worn accelerometer

Lyden, K, John, D, Dall, P and Granat, MH 2016, 'Differentiating sitting and lying using a thigh-worn accelerometer' , Medicine & Science in Sports & Exercise, 48 (4) , pp. 742-747.

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Abstract

A tri-axial accelerometer worn on the thigh can provide information on the angle of rotation of the thigh. These data may be used to estimate periods of lying versus sitting. Purpose: To develop and test a classification algorithm to identify sedentary events as either lying or sitting events using a thigh-worn, tri-axial accelerometer. Methods: Seven day free-living activity from 14 sedentary workers was recorded using the activPAL3TM monitor. Participants recorded when they went to bed and when they got up in a diary. All “in bed” sedentary events were assumed to be lying and all “not in bed” sedentary events as sitting. An algorithm computed the angle of rotation of the y-axis, which was used to detect orientation of the thigh. Crossing a rotational threshold in the transverse plane of ±65was used to classify a sedentary event as lying. The classification accuracy of the algorithm was compared to self-reported classification from the diary. Results: The algorithm classified 96.7% of the sedentary time “in bed” (sensitivity) as lying and 92.9% of the time “not in bed” as not lying (specificity). Conclusion: Tri-axial accelerometer data recorded from a single site on the thigh can be used to classify sedentary events as sitting and lying. The automated method developed in this study will allow objective measurement of diurnal lying time and that while sleeping without relying on self-report. This will help advance the understanding of the impact of different types of sedentary behaviours on various health outcomes.

Item Type: Article
Schools: Schools > School of Health Sciences > Centre for Health Sciences Research
Schools > School of Health Sciences
Journal or Publication Title: Medicine & Science in Sports & Exercise
Publisher: American College of Sports Medicine
ISSN: 0195-9131
Related URLs:
Funders: Non funded research
Depositing User: MH Granat
Date Deposited: 16 Nov 2015 16:49
Last Modified: 22 Mar 2016 10:28
URI: http://usir.salford.ac.uk/id/eprint/37074

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