Testing a Novel Accelerometry Site - Better Than Wrist, More Acceptable Than Hip? Chest Wins!

Abstract

The default Actigraph accelerometer position has traditionally been on the Hip due to its close proximity to the centre of mass (CoM), but often results in low participant compliance (often <50%). This has resulted in the alternative Wrist site being used to dramatically raise compliance but ultimately compromises measurement as it is quite remote from the CoM. A better alternative is needed. PURPOSE: To determine if our new Chest site (using a necklace) can provide measurements significantly superior to the Wrist, yet has high compliance and provides results more comparable to the Hip. METHODS: A group of healthy 44 young adults (22 male) wore GT3X+ accelerometers simultaneously at their Hip, Wrist, and Chest during a series of slow (2.4-3.2kph), average (4.0-6.4kph) and fast (7.2-8.0kph) walking speeds in 4 min bouts on a treadmill. Correlations and absolute percentage errors of the vector magnitude counts were computed between each measurement site. RESULTS: For slow, average, and fast walking respectively, weak correlations were seen between the Waist v Hip of 0.23, 0.44, and 0.72; in comparison the respective correlations between Waist v Chest were much higher: 0.64, 0.84, and 0.91. Using the Hip as criterion, the mean percentage errors for slow, average and fast speeds were also much lower for the Chest site (23%, 15%, and 19% respectively) compared to the Wrist (43%, 38%, and 120% respectively). Preliminary data suggests that participants also felt the Chest site was more acceptable than the Hip site. CONCLUSION: This new Chest site provides data that is superior than the Wrist, whilst being very comparable, but with higher acceptability, to the Hip. Our new Chest site using a necklace provides preliminary data to suggest it should be considered a superior site for those participants who predominantly walk. We are currently undertaking further studies in semi-controlled and free-living conditions to examine this site further. Funding: Hong Kong University Seed Fund for Basic Research