Agreement between activPAL3c accelerometers placed at different thigh positions.

ActivPAL3c triaxial accelerometers are increasingly used to assess physical activity and sedentary behaviours. However, little is known how attachment site (left vs. right or upper vs. lower thigh) affects activPAL3c accelerometer outcomes. Twenty-eight adults wore four activPAL3c accelerometers attached 2cm above and below the midpoint of the left and right thigh during five minutes of laboratory-based walking at a self-selected pace, treadmill walking at 0.89 and 1.56m/s, and treadmill running at 2.22m/s, and during approximately seven hours of free-living conditions. One-way ANOVA revealed no statistically significant differences in accelerometer output between ActivPAL3c accelerometers at these locations during both laboratory-based, and free-living conditions. Intraclass correlation coefficients showed a high level of agreement between activPAL3c accelerometers during laboratory and free living activities (ICC(2,1) 0.76-1.00). The attachment sites used in this study do not appear to significantly influence outcomes for step count, sitting or walking time, or number of postural transitions from triaxial activPAL3c accelerometers during laboratory-based walking or free-living conditions. Therefore if necessary, to enhance participant compliance during monitoring periods, these sites could be used interchangeably. Studies of longer duration incorporating additional laboratory and recreational activities are needed to confirm these findings.