Comparing Five Generations of ActiGraph Devices Using an Orbital Shaker.

Area of Science:

• Biomedical Engineering
• Wearable Technology
• Physical Activity Measurement

Background:

• ActiGraph accelerometers are widely used for objective assessment of physical activity, sedentary behavior, and sleep.
• Validation of different ActiGraph sensor generations is crucial due to potential hardware or firmware changes.

Purpose of the Study:

• To objectively validate five generations of ActiGraph sensors.
• To characterize potential differences in output across generations.
• To assess agreement with a criterion accelerometer under controlled conditions.

Main Methods:

• Utilized an orbital shaker to generate accelerations from 0 to 3700 milli-g.
• Tested wGT3X-BT, GT9X, CentrePoint Insight Watch (CPIW) 1.0 and 2.0, and GT3X+ devices.
• Primary outcome was raw vector magnitude (VM) agreement (absolute and relative) to a calibrated 3DM accelerometer.

Main Results:

• Observed inter- and intragenerational differences in static offset, particularly at lower accelerations.
• All generations met ±5% relative agreement and ±50 mg absolute agreement limits below 3000 milli-g.
• Small drift was noted relative to the acceleration signal, with variations mitigated by post-hoc calibration or integrated units (counts, MIMS).

Conclusions:

• Small differences in raw ActiGraph output exist across five generations but are generally within acceptable limits.
• Variability is minimized when using autocalibration or expressing data in MIMS or counts.
• ActiGraph devices demonstrate largely consistent performance for free-living physical activity assessment across generations.