The Validity of Consumer-Level Activity Monitors in Healthy Older Adults in Free-Living Conditions.

Consumer-level activity monitors, such as Fitbit and Misfit devices, are a popular and low-cost means of measuring physical activity. This study aims to compare the accuracy of step counts from two consumer-level activity monitors against two reference devices in healthy, community-dwelling older adults in free-living conditions. Twenty-five older adults (aged 65-84) simultaneously wore 5 devices (e.g., Misfit Shine and Fitbit Charge HR) over 7 consecutive days. All consumer-level activity monitors positively correlated with reference devices (p < .001). There was also substantial to near perfect agreement between all consumer-level activity monitors and reference devices. Compared to the ActiGraph GT3X+, the waist-worn Misfit Shine displayed the highest agreement amongst the devices worn (ICC = 0.96, 95% 0.91 to 0.99). The wrist-worn devices showed poorer agreement to reference devices. Future research needs to consider that not all consumer-level activity monitors are equal in terms of accuracy, design, and function.