To use the most recent ActiGraph model (GT9X) to compare counts per minute (CPM) estimates between wrist-worn and waist-worn attachment sites.
Participants completed 2 conditions (laboratory [N = 13] and free-living conditions [N = 9]), in which during both of these conditions they wore 2 ActiGraph GT9X accelerometers on their nondominant wrist (side-by-side) and 2 ActiGraph GT9X accelerometers on their right hip in line with the midaxillary line (side-by-side). During the laboratory visit, participants completed 5 treadmill-based trials all lasting 5 min: walk at 3 mph, 3.5 mph, 4 mph, and a jog at 6 mph and 6.5 mph. During the free-living setting, participants wore the monitors for 8 hours. Paired t test, Pearson correlation and Bland-Altman analyses were employed to evaluate agreement of CPM between the attachment sites.
Across all intensity levels and setting (laboratory and free-living), CPM were statistically significantly and substantively different between waist- and wrist-mounted accelerometry.
Attachment site drastically influences CPM. As such, extreme caution should be exercised when comparing CPM estimates among studies employing different attachment site methodologies, particularly waist versus wrist.
The authors are with the Dept of Health, Exercise Science, and Recreation Management, The University of Mississippi, University, MS.