HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Free Full Text (PDF) Free All Versions of this Article: 105/4/1091    most recent 90641.2008v1 Submit a response View responses Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Rothney, M. P. Articles by Chen, K. Y. Search for Related Content PubMed PubMed Citation Articles by Rothney, M. P. Articles by Chen, K. Y.

Comparing the performance of three generations of ActiGraph accelerometers

¹Department of Biomedical Engineering, Vanderbilt University, and ²Department of Biostatistics, Vanderbilt University Medical Center, Nashville, Tennessee; and ³National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases\Clinical Endocrinology Branch, Bethesda, Maryland

Submitted 13 May 2008 ; accepted in final form 15 July 2008

ActiGraph accelerometers are a useful tool for objective assessment of physical activity in clinical and epidemiological studies. Several generations of ActiGraph are being used; however, little work has been done to verify that measurements are consistent across generations. This study employed mechanical oscillations to characterize the dynamic response and intermonitor variability of three generations of ActiGraph monitors, from the oldest 7164 (n = 13), 71256 (n = 12), to the newest GT1M (n = 12). The response due to independent radius (22.1–60.4 mm) and frequency (25–250 rpm) changes were measured, as well as intermonitor variability within each generation. The 7164 and 71256 have similar relationships between activity counts and radius (P = 0.229) but were significantly different from the GT1M (P < 0.001). The frequency responses were nonlinear in all three generations. Although the response curve shapes were similar, the differences between generations at various frequencies were significant (P < 0.017), especially in the extremes of the measurement range. Intermonitor variability was markedly reduced in the GT1M compared with the 7164 and 71256. Other measurement differences between generations include decreased peak counts and decreased sensitivity in low-frequency detection in the GT1M. The results of this study revealed an improvement of the intermonitor variability by the GT1M monitor. However, the reduced sensitivity in low-count ranges in the GT1M may not be well suited for monitoring sedentary or light-intensity movements. Furthermore, the algorithms for energy expenditure predictions developed using older 7164 monitors may need to be modified for the GT1M.

calibration; mechanical testing

This article has been cited by other articles:

				S. Brage, V. T. van Hees, and N. Brage Intergeneration accelerometer differences and correction for on-board frequency-based filtering J Appl Physiol, April 1, 2009; 106(4): 1473 - 1473. [Full Text] [PDF]