Feasibility Of A Novel Accelerometer Attachment-site For The Measurement Of Energy Expenditure

Abstract

Energy expenditure (EE) is an important behavioral contributor to the current obesity pandemic, therefore accurate measures of EE are needed. It has been suggested accelerometers are affordable devices to provide valid estimates of EE, however, the controversy over which attachment-site for an accelerometer is the most accurate and feasible/compliant for this purpose continues. The Waist and Wrist sites are commonly used in research and both have well-documented strengths and weaknesses. Recently, there has been a growing interest in the Chest attachment-site as it has the advantages of being hidden from view but close to the center of mass and therefore the potential to provide accurate estimates of EE. PURPOSE: To determine if wearing the GT3X+ at the Chest (like a neck-pendant, beneath clothing) can provide valid estimates of EE. METHODS: A group of 10 young adults (20-26 years) wore GT3X+ accelerometers simultaneously at their Waist, Wrist, and Chest, whilst undertaking bouts of slow, medium and fast speeds (4.0, 6.4 and 8.0 kph, respectively) of walking and jogging on a treadmill. EE was measured by a primary criterion (indirect calorimetry, Cortex Metamax 3B), and a secondary criterion (BodyMedia SenseWear). For each attachment-site, a Friedman test was used to compare GT3X+ estimated EE (3-min of steady-state at each speed) against the primary criterion EE. Pairwise comparisons were performed with a Bonferroni correction for multiple comparisons. RESULTS: The median total EE measured by GT3X+ was significantly different across the attachment-sites (p < 0.005). Post hoc analysis revealed significant differences between the primary criterion EE (17.2kcal) and GT3X+ measured EE at the Wrist (9.0kcal, p < 0.005) but not the Chest (16.5kcal, p=0.79) or the Waist (16.2kcal, p=0.25). The Chest site (16.5kcal) and secondary criterion (15.5kcal, p= 0.66) were also similar. CONCLUSIONS: Preliminary results of this study suggest that the novel Chest attachment-site is able to provide valid estimates of EE compared to both the primary and secondary criterion. We are currently undertaking further data collection to increase our sample size. Funding: Hong Kong University Seed Fund for Basic Research.