The acceleration dependent validity and reliability of 10Hz GPS

Akenhead, Richard, French, Duncan, Thompson, Kevin and Hayes, Phil (2014) The acceleration dependent validity and reliability of 10Hz GPS. Journal of Science and Medicine in Sport, 17 (5). pp. 562-566. ISSN 1878-1861

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Official URL: http://dx.doi.org/10.1016/j.jsams.2013.08.005

Abstract

Objective - To examine the validity and inter-unit reliability of 10Hz GPS for measuring instantaneous velocity during maximal accelerations.

Design - Experimental.

Methods - Two 10Hz GPS devices secured to a sliding platform mounted on a custom built monorail were towed whilst sprinting maximally over 10m. Displacement of GPS devices was measured using a laser sampling at 2000Hz, from which velocity and mean acceleration were derived. Velocity data was pooled into acceleration thresholds according to mean acceleration. Agreement between laser and GPS measures of instantaneous velocity within each acceleration threshold was examined using least squares linear regression and Bland-Altman limits of agreement (LOA). Inter-unit reliability was expressed as typical error (TE) and a Pearson correlation coefficient.

Results - Mean bias+/-95% LOA during accelerations of 0-0.99ms-2 was 0.12+/-0.27ms-1, decreasing to -0.40+/-0.67ms-1 during accelerations >4ms-2. Standard error of the estimate +/-95% CI (SEE) increased from 0.12+/-0.02ms-1 during accelerations of 0-0.99ms-2 to 0.32+/-0.06ms-1 during accelerations >4ms-2. TE increased from 0.05+/-0.01 to 0.12+/-0.01ms-1 during accelerations of 0-0.99ms-2 and >4ms-2 respectively.

Conclusion - The validity and reliability of 10Hz GPS for the measurement of instantaneous velocity has been shown to be inversely related to acceleration. Those using 10Hz GPS should be aware that during accelerations of over 4ms-2, accuracy is compromised.

Item Type: Article
Additional Information: Available online 29/8/2013 ahead of print publication.
Uncontrolled Keywords: Global positioning, time motion, team sports, monitoring
Subjects: C600 Sports Science
Department: Faculties > Health and Life Sciences > School of Life Sciences > Sport, Exercise and Rehabilitation
Depositing User: Ellen Cole
Date Deposited: 19 Feb 2014 15:18
Last Modified: 10 Aug 2015 11:26
URI: http://nrl.northumbria.ac.uk/id/eprint/15469

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