Validation of the ActiGraph GT3X and activPAL Accelerometers for the Assessment of Sedentary Behavior

Abstract

This study examined (a) the validity of two accelerometers (ActiGraph GT3X [ActiGraph LLC, Pensacola, FL, USA] and activPAL [PAL Technologies Ltd., Glasgow, Scotland]) for the assessment of sedentary behavior; and (b) the variations in assessment accuracy by setting minimum sedentary bout durations against a proxy for direct observation using an automated wearable camera in free-living environments. Time spent in sedentary behavior estimated from the GT3X, with varying identification methods (i.e., a hybrid machine learning algorithm, Sojourn, and activity count thresholds), and the activPAL were compared to the criterion measure with and without applying minimum sedentary bout durations. The activPAL assessed sedentary behavior most accurately followed by GT3X with the Sojourn method. The performance of the GT3X is improved when identifying sedentary bouts ≥ 15 min with the Sojourn method or a threshold of < 150 cpm. The activPAL should be considered for studies focusing on sedentary behavior. The ability of the GT3X to assess sedentary behavior is improved when focusing on sedentary bouts ≥ 15 min using the Sojourn method or the threshold of < 150 cpm.

Keywords:

• accelerometry
• ActiGraph
• activPAL
• measurement
• physical activity

ACKNOWLEDGMENTS

The authors wish to express their sincere appreciation to Dr. David Rowe, the guest editor of the Special Issue, and anonymous referees for the helpful comments and discussion on the manuscript. The authors are also grateful to Dr. Jacqueline Kerr at the University of California-San Diego for providing a standardized coding protocol of the SenseCam image data.

This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors. There are no conflicts of interest.