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<0.001). 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.