Validation of Physical Activity Estimated Using Wearable Devices under Free-living Conditions

Abstract

PURPOSE: Higher physical activity (PA) in daily life is associated with a decrease in the risk of all-cause mortality and in prevalence of non-communicable diseases (NCDs). Thus, accurate estimation of PA is important for increasing PA and promoting the NCDs prevention. This study was performed to examine the validity of PA energy expenditure (PAEE) and PA level (PAL) estimated using twelve wearable devices under free-living conditions. METHODS: Nineteen healthy adults (9 men and 10 women) aged 21-50 years wore 12 wearable devices simultaneously (five wearable devices on the waist, five on the wrist and two in the pocket including those for the consumer and the research) for consecutive 15 days in a free-living condition. PAEEs were calculated by subtracting the basal metabolic rate (BMR) from the total energy expenditure (TEE) obtained from each device application. PALs were calculated by dividing the TEE by BMR. Because some devices did not show BMR in device applications, TEE values in a day when the devices were stationary were used as BMRs. The reference PAEE and PAL were calculated by using the TEE measured by doubly labeled water (DLW) method during 15 days worn 12 wearable devices and the BMR estimated on the sleeping metabolic rate (SMR) by the metabolic chamber method on a different day. RESULTS: The mean value of reference PAEE and PAL for 15 days were 1064 ± 196 kcal/d (696 to 1541 kcal/d) and 1.88 ± 0.21 (1.51 to 2.23), respectively. Spearman’s rank correlation coefficients between the reference PAEE and the estimated PAEE were significant in four wearable devices (r=0.498-0.579, p < 0.05), those for PAL were significant in neither wearable devices. CONCLUSIONS: The accurate ranking among individuals based on PAEE and PAL seems difficult. These results suggest that the estimation of PA using wearable devices needs to be cautiously considered.This research was supported by the Japan Agency for Medical Research and Development (AMED).