LONGITUDINAL VALIDITY OF ACCELEROMETRY IN YOUTH
Primary Investigator: Karin Pfeiffer

Accelerometers are the method of choice for measuring physical activity in free living children and adolescents; however, interpreting their output is problematic. Factors related to growth and development influence the activity counts recorded by an accelerometer. Existing algorithms used to convert raw accelerometer counts to units of energy expenditure and/or physical activity intensity do not adequately take into account developmental differences and are based on cross-sectional data. A second issue is the fact that researchers do not know if the existing equations or cut-points are sufficiently sensitive to detect the small changes in free-living activity behavior that are typically induced by intervention programs.

The specific aims of this study are to:
1) evaluate and compare the longitudinal validity of previously published energy expenditure calibration equations/algorithms for the Actigraph, Actical, and RT3 accelerometers in an age-diverse cohort of children and adolescents (6 - 15 yrs)

2) determine if accelerometers and their respective count cut-points are sufficiently sensitive to detect the changes in moderate-to-vigorous physical activity (MVPA) that would typically be induced by a physical activity intervention program.

We will use a longitudinal design and conduct evaluations at 12-, 24- and 36 months follow-up.

Student Assistants: Justin Bland, Anna Hunsinger, Megan Holmes, Kyle Morrison, Tiffany Prout, and Laura Vielbig

Funded by the National Institute for Child Health and Development