Comparability of Postural and Physical Activity Metrics from Different Accelerometer Brands Worn on the Thigh: Data Harmonization Possibilities

Abstract

The aim was to establish which postural and physical activity outcomes are comparable across different accelerometer brands worn on the thigh when processed using open-source methods. Twenty participants wore four accelerometers (Axivity, ActiGraph, activPAL, GENEActiv) for three free-living days. Postural and physical activity outputs (average acceleration, intensity gradient, intensity of the most active 30 min, 60 min, and 8 h) were generated. Postural outputs: Mean absolute percent errors (MAPEs) were low, reliability excellent, and equivalency within the 5% zone across all monitor pairings for sitting/lying and upright times, but not specific lying postures. Physical activity outputs: MAPEs were higher and reliability lower than for sitting/lying and upright time. However, the majority of the outcomes were within the 10% equivalency zone for Axivity/ GENEActiv and Axivity/ActiGraph pairings. Total sitting/lying and upright times show strong potential for harmonization across studies utilizing different thigh-worn accelerometers. The majority of acceleration outcomes compare well for Axivity, GENEActiv, and ActiGraph.

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“…While these cut-points were developed using GENEActiv devices, the GENEActiv and Axivity accelerometers have shown excellent equivalence and agreement across most raw data outcome measures. 13 , 23 Furthermore, AvAcc (m g ), intensity gradient (IG), and the acceleration above which a person's most active 180, 60, 45, 30, 15, and 5 min were accumulated (MX metrics; m g ), are reported from GGIR output Part 2. The AvAcc is a direct measure of dynamic acceleration and is used as a single metric for the overall activity averaged per day.…”

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“…Both devices are worn on the midline of the anterior thigh between the hip and the knee joint, based on manufacturers' recommendations and previous validation studies [ 6 , 7 ]. Wearing accelerometers on the thigh has become a wear position of interest for the researchers because of its accuracy in measuring postural component of sedentary behaviours as well as active physical behaviours [ 8 ].…”

Development and Evaluation of Sedentary Time Cut-Points for the activPAL in Adults Using the GGIR R-Package

“…With recent technological advancements, tri-axial research grade accelerometers can provide users with the collected raw accelerometer data that can facilitate comparisons between devices using identical processing methods. Using open-source accelerometer processing and analyzing software such as GGIR, previous studies have examined the comparability of the same/different devices within and between body locations with promising findings for future data harmonization [18][19][20]. The widely used raw acceleration MVPA cut-point of 100 milli-gravitational units (mg) is often applied to raw acceleration accelerometer data to estimate time spent in MVPA, and to facilitate comparisons between devices [18,21].…”

“…One such approach that removes the reliance upon using proprietary algorithms from PAL Technologies Ltd. to process data collected from the activPAL device has recently been proposed [20]. As the activPAL device collects raw acceleration data across three axis, the raw data can be downloaded using PAL Technologies Ltd. freely available software and saved in raw format as .csv files, to be subsequently processed using the opensource software GGIR [20,26].…”

“…One such approach that removes the reliance upon using proprietary algorithms from PAL Technologies Ltd. to process data collected from the activPAL device has recently been proposed [20]. As the activPAL device collects raw acceleration data across three axis, the raw data can be downloaded using PAL Technologies Ltd. freely available software and saved in raw format as .csv files, to be subsequently processed using the opensource software GGIR [20,26]. Notwithstanding the obvious benefits of transparency and reproducibility for the research community when using GGIR, users also have the ability to adapt and expand the functionality of GGIR by specifying certain input arguments and/or selecting certain output variables.…”