Systematic review of the validity and reliability of consumer-wearable activity trackers.

Abstract in brief

• The systematic review examined the accuracy and consistency of popular consumer activity trackers, Fitbit and Jawbone, in measuring steps, distance, physical activity, energy expenditure, and sleep, based on 22 studies published up to July 2015.
• Laboratory studies showed high correlation with tracker-assessed steps (Pearson or intraclass correlation coefficients around 0.80), but there was limited data on distance accuracy, with Fitbit overestimating at slow speeds and underestimating at fast speeds.
• In field settings, physical activity estimates varied, with some studies showing high correlation, but overall energy expenditure was often underestimated, while sleep metrics like total sleep time and sleep efficiency were overestimated compared to polysomnography; inter-device reliability was generally high for Fitbit but unstudied for Jawbone.]