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Translation equations to compare ActiGraph GT3X and Actical accelerometers activity counts
1School of Physiotherapy and Curtin Health Innovation Research Institute, Curtin University, Perth, Australia. Straker@curtin.edu.au
BMC Medical Research Methodology
|April 24, 2012
Summary
A new equation allows accurate minute-by-minute comparison between Actical and ActiGraph accelerometers. This vertical conversion method enhances data synthesis across studies using these physical activity monitors.
Area of Science:
- Biomedical Engineering
- Kinesiology
- Physical Activity Measurement
Background:
- Comparing accelerometer data is crucial for synthesizing research.
- Actical and ActiGraph GT3X are commonly used accelerometers with different measurement axes.
- A standardized conversion method is needed for minute-by-minute data.
Purpose of the Study:
- To develop a translation equation for comparing Actical and ActiGraph GT3X accelerometer counts.
- To establish a reliable minute-by-minute conversion algorithm.
Main Methods:
- Ten participants (5 male, 5 female) wore Actical and ActiGraph GT3X accelerometers simultaneously for two days.
- Conversion algorithms were calculated between Actical and three ActiGraph outputs (vertical, combined vector, custom vector).
- R-squared values were determined for day-by-day and full data sets.
Main Results:
- The algorithm y = 0.905x showed the strongest correlation between Actical and the vertical component of ActiGraph data.
- Consistent moderate to strong conversions were observed (R-squared: 0.514–0.989 day-by-day, 0.865 full data set).
- Actical is most sensitive to vertical accelerations, correlating less with 3D ActiGraph output.
Conclusions:
- Minute-by-minute conversions between Actical and ActiGraph vertical data are reliable.
- The developed equation facilitates data synthesis between studies using these devices.
- This method enhances the comparability of physical activity research findings.
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