Concurrent Validity of Actigraph-Determined Sedentary Time Against the Activpal Under Free-Living Conditions in a Sample of Bus Drivers

ABSTRACT

This study explored the validity of ActiGraph-determined sedentary time (<50 cpm, <100 cpm, <150 cpm, <200 cpm, <250 cpm) compared with the activPAL in a free-living sample of bus drivers. Twenty-eight participants were recruited between November 2013 and February 2014. Participants wore an activPAL3 and ActiGraph GT3X+ concurrently for 7 days and completed a daily diary. Time spent sedentary during waking hours on workdays, non-workdays, during working-hours, and non-working hours were compared between instruments. During working hours, all ActiGraph cut-points significantly underestimated sedentary time (p < 0.05), whereas during non-working hours the <50 cpm cut-point demonstrated the closest agreement (ActiGraph sedentary time: 250 ± 75 minutes versus activPAL sedentary time: 236 ± 65 minutes). Receiver operating characteristic analyses revealed that on workdays and non-workdays the ActiGraph cut-points exhibited relatively low sensitivity (all <0.62) and specificity (all <0.49) values. The use of the ActiGraph to measure sedentary time in this understudied, highly sedentary and at risk occupational group is not recommended.

KEYWORDS:

• Actigraph
• activPAL
• bus drivers
• sedentary behavior
• validation

Acknowledgments

The research was supported by the National Institute for Health Research (NIHR) Leicester Biomedical Research Centre. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.