Assessing sedentary behavior using wearable devices: An overview and future directions

Abstract

Accurate assessments of sedentary behavior are critically important to monitor the proportion of prolonged sedentary behavior, to investigate causal relationships with health out-comes, and to test the effectiveness of interventions aimed at reducing sedentary behaviors. The purpose of this review was to provide an overview of assessments of sedentary behavior using wearable devices, and to briefly discuss the future directions of this field. Sedentary behavior is defined as any waking activity characterized by energy expenditure ≤ 1.5 metabolic equivalents and a sitting or reclining posture. Globally accepted wearable devices to assess sedentary be-havior are ActiGraph (developed in the United States of America) and activPAL (developed in Scotland). The ActiGraph, worn at the waist, classifies sedentary behavior based on its unique metric of 'counts' less than 100 per minute. The activPAL is attached to a participant's thigh, and classifies sedentary behavior using an inclinometer with a proprietary algorithm. In Japan, Omron's Active style Pro is the most widely used device to measure sedentary behavior. A systematic review on sedentary behavior measurements in Japan found that almost all studies adopted this device. A data reduction approach is a key process to obtain consistent summary statistics of sedentary behavior. To accomplish this, seven R packages have been developed, mainly for ActiGraph and activPAL. Unfortunately, none of these can integrate data from Japanese devices; although a macro program for processing data from Active style Pro has been developed. Use of activity recognition techniques and multi-sensor devices may reduce measurement errors, and provide contextual information on sedentary behavior. Other chal-lenges include standardization and harmonization of measurement protocols. Tackling these challenges may facilitate international comparisons in sedentary behavior and eventually study integrations.