The accuracy of the SenseWear Pro3 and the activPAL3 Micro devices for measurement of energy expenditure

Activity monitors such as the SenseWear Pro3 (SWP3) and the activPAL3 Micro (aP³M) are regularly used by researchers and practitioners to provide estimates of the metabolic cost (METs) of activities in free-living settings. The purpose of this study is to examine the accuracy of the MET predictions from the SWP3 and the aP³M compared to the criterion standard MET values from indirect calorimetry. Fifty-six participants (mean age: 39.9 (±11.5), 25M/31F) performed eight activities (four daily living, three ambulatory and one cycling), while simultaneously wearing a SWP3, aP³M and the Cosmed K4B² (K4B²) mobile metabolic unit. Paired samples T-tests were used to examine differences between device predicted METs and criterion METs. Bland-Altman plots were constructed to examine the mean bias and limits of agreement for predicted METs compared to criterion METs. SWP3 predicted MET values were significantly different from the K4B² for each activity (p ≤0.004), excluding sweeping (p = 0.122). aP³M predicted MET values were significantly different (p < 0.001) from the K4B² for each activity. When examining the activities collectively, both devices underestimated activity intensity (0.20 METs (SWP3), 0.95 METs (aP³M)). The greatest mean bias for the SWP3 was for cycling (-3.25 METs), with jogging (-5.16 METs) producing the greatest mean bias for the aP³M. All of the activities (excluding SWP3 sweeping) were significantly different from the criterion measure. Although the SWP3 predicted METs are more accurate than their aP³M equivalent, the predicted MET values from both devices are significantly different from the criterion measure for the majority of activities.