Article

Calibration of accelerometer output for children

Department of Exercise Science, University of Massachusetts, Amherst, MA 01003, USA.
Medicine &amp Science in Sports &amp Exercise (Impact Factor: 4.46). 12/2005; 37(11 Suppl):S523-30. DOI: 10.1249/01.mss.0000185658.28284.ba
Source: PubMed

ABSTRACT Understanding the determinants of physical activity behavior in children and youths is essential to the design and implementation of intervention studies to increase physical activity. Objective methods to assess physical activity behavior using various types of motion detectors have been recommended as an alternative to self-report for this population because they are not subject to many of the sources of error associated with children's recall required for self-report measures. This paper reviews the calibration of four different accelerometers used most frequently to assess physical activity and sedentary behavior in children. These accelerometers are the ActiGraph, Actical, Actiwatch, and the RT3 Triaxial Research Tracker. Studies are reviewed that describe the regression modeling approaches used to calibrate these devices using directly measured energy expenditure as the criterion. Point estimates of energy expenditure or count ranges corresponding to different activity intensities from several studies are presented. For a given accelerometer, the count cut points defining the boundaries for 3 and 6 METs vary substantially among the studies reviewed even though most studies include walking, running and free-living activities in the testing protocol. Alternative data processing using the raw acceleration signal is recommended as a possible alternative approach where the actual acceleration pattern is used to characterize activity behavior. Important considerations for defining best practices for accelerometer calibration in children and youths are presented.

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    • "Children were included in the study if they accumulated at least two weekdays and one weekend day with at least 10 h of wearing time. Age-dependant cut-offs (Freedson et al. 2005) were used to define moderate-tovigorous physical activity (MVPA), while SB was defined as an intensity of less than 100 counts per minute (cpm) (Trost et al. 2011). "
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    • "Adolescents were instructed to wear the accelerometer for 7 consecutives days at the lower back fitted with an elastic belt, excepted during sleep hours and water-based activities. The Freedson's age-specific cut-points were used to estimate intensities of total PA, moderate PA and vigorous PA (Freedson et al., 2005). Variables obtained by the ActiGraph accelerometer were analyzed as counts per minute (cpm) for total PA and min/day for levels of PA. "
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