Wearable-device-measured physical activity and future health risk.

Abstract

Use of wearable devices that monitor physical activity is projected to increase more than five-fold per half-decade 1. We investigated how device-based physical activity energy expenditure (PAEE) and different intensity profiles were associated with all-cause mortality. We used a network harmonisation approach to map dominant wrist acceleration to PAEE in 96,476 UK Biobank participants (mean age 62 years, 56% female). We also calculated the fraction of PAEE accumulated from moderate-to-vigorous physical activity (MVPA). Over the median 3.1 year follow-up period (302,526 person-years), 732 deaths were recorded. Higher PAEE was associated with a lower hazard of all-cause mortality for a constant fraction of MVPA, e.g. 21% (95% CI 4-35%) lower hazard for 20 versus 15 kJ/kg/d PAEE with 10% from MVPA. Similarly, higher MVPA fraction was associated with a lower hazard when PAEE remained constant, e.g. 30% (8-47%) lower hazard when 20% versus 10% of a fixed 15 kJ/kg/d PAEE volume was from MVPA. Our results show that higher volumes of PAEE are associated with reduced mortality rates, and achieving the same volume through higher intensity activity is associated with greater reductions than through lower intensity activity. The linkage of device-measured activity to energy expenditure creates a framework for using wearables for personalised prevention.