Impact of walking aids on estimating physical activity using a tri-axial accelerometer in frail older adults

Objectives This study aimed to compare the estimation error of physical activity level (PAL) estimated using a tri-axial accelerometer between an independent walking group and an assisted walking group with walking aids. Methods Subjects were 6 older adults who could walk independently and 10 older adults requiring walking assistance during gait. Total energy expenditure (TEE) was measured using the doubly labelled water (DLW) method over 2 weeks and PAL was calculated as the measured TEE divided by the basal metabolic rate measured using indirect calorimetry (PAL DLW). The participants wore a tri-axial accelerometer (Active style Pro HJA-750C) on the waist simultaneously as the DLW period, and the estimated PAL was derived from it (PAL ACC). Results The median PAL estimation error in the assisted walking group was -0.30 kcal/day (range: -0.77 to -0.01 kcal/day) and more underestimated than that in the independent walking group (p=0.02). The estimation error of PAL ACC was significantly correlated with PAL DLW (r=-0.80, p<0.01). Conclusions Using the accelerometer, PAL was underestimated for older adults who used walking aids but not for those who walked independently under free-living conditions.