Objectives: A "proof-of-concept" study to examine the feasibility of wearing an Actigraph GT3X+ at the Chest (resembling a neck pendant) for physical activity measurement.
Design: A convenience sample of 45 healthy adults (23 male, mean age 20.0±4.5 years) was included in data analysis.
Methods: Participants simultaneously wore three GT3X+ accelerometers, on the Waist, Wrist, and Chest and completed 8 bouts of slow (.67, .89, 1.11m/s), average (1.33, 1.56, 1.78m/s) and fast (2.00, 2.22m/s) walking on a treadmill. Paired t-test, correlations and absolute percentage errors (APE) of accelerometer output (vector magnitude, VM) were computed for the key pairs: Waist-Wrist; and Waist-Chest.
Results: The Wrist-site overestimated VM to a greater extent at all speeds in comparison to the Chest. Pearson's r correlations were weaker for Waist-Wrist (<.80) in comparison to the Waist-Chest (>.85). The APE's were much lower (i.e. higher agreement) for the Chest (9.23-15.5%) compared to the Wrist (19.7-54.9%). Participants also felt the Chest-site was more acceptable than the Waist-site.
Conclusions: PA measurements recorded by a Chest worn GT3X+ more closely resembled PA measurements recorded at the traditional Waist site than when compared to the Wrist site. When combined with high Chest site preference, the findings of our study suggest that the Chest is a feasible site for accelerometer wear.
Keywords: Actigraph; Activity monitors; Measurement; Objective monitoring; Treadmill; Wrist worn.
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