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ActiGraph is the most common accelerometer in physical activity research, but it has measurement errors due to restrictive frequency filtering. This study investigated biomechanically how different frequency filtering of accelerometer data affects assessment of activity intensity and age-group differences when measuring physical activity. Data from accelerometer at the hip and motion capture system was recorded during treadmill walking and running from 30 subjects in three different age groups: 10, 15, and >20 years old. Acceleration data was processed to ActiGraph counts with original band-pass filter at 1.66 Hz, to counts with wider filter at either 4 or 10 Hz, and to unfiltered acceleration according to "Euclidian norm minus one" (ENMO). Internal and external power, step frequency, and vertical displacement of center of mass (VD) were estimated from the motion capture data. Widening the frequency filter improved the relationship between higher locomotion speed and counts. It also removed age-group differences and decreased within-group variation. While ActiGraph counts were almost exclusively explained by VD, the counts from the 10 Hz filter were explained by VD and step frequency to an equal degree. In conclusion, a wider frequency filter improves assessment of physical activity intensity by more accurately capturing individual gait patterns.
Pubmed ID: 30314272
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Multi paradigm numerical computing environment and fourth generation programming language developed by MathWorks. Allows matrix manipulations, plotting of functions and data, implementation of algorithms, creation of user interfaces, and interfacing with programs written in other languages, including C, C++, Java, Fortran and Python. Used to explore and visualize ideas and collaborate across disciplines including signal and image processing, communications, control systems, and computational finance.
View all literature mentionsCommercial instrument supplier for human activity monitors. ActiGraph devices are used by researchers and clinicians in hundreds of universities and research organizations in more than 56 countries. ActiGraph activity monitors are the most validated and widely used devices of their kind. ActiGraph activity monitors use triaxial accelerometers and our validated proprietary filtering algorithms to accurately measure the amount and intensity of human activity. They are powered by rechargeable lithium ion batteries, and battery charging and communication are accomplished via a standard USB connection. All ActiGraph activity monitors can be worn at the waist or wrist and are suitable for subjects of all ages. ActiGraph devices have been used in hundreds of research studies in nearly 60 countries around the world since 1992. Leading research facilities including the U.S. National Institute of Health (NIH), the Institute of Child Health in the UK, and Karolinska Institutet in Sweden rely on our products to provide objective activity measurement in dozens of areas including obesity, diabetes, sleep, elderly behavior, and athletics. ActiGraph often works with scientific organizations to develop and implement software and hardware features that reflect the evolving needs of the research community. ActiGraph devices are well recognized as some of the most accurate activity measurement products on the market. Extensive research has confirmed our accuracy against the VO2 and doubly labeled water (DLW) methods of estimating energy expenditure. Keywords: Device, Researcher, Clinician, University, Research, Organization, Obesity, Diabetes, Sleep, Elderly, Behavior, Athletics, Scientific, Activity monitor, Physical, Measurement, Human, Activity,
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