Concurrent validity of Nokia Go activity tracker in walking and free-living conditions.

RATIONALE, AIMS, AND OBJECTIVES: Consumer-based activity trackers aim at quantifying physical activity in a wide range of contexts. Nevertheless, they need to be validated before they are confidently used. This study assessed the concurrent validity of the Nokia Go against reference devices, according to different sensor locations, in two measurement conditions: during a walking task and during a 24-hour free-living condition.

METHODS: We examined the agreement between devices and between locations in the number of steps and total sleep time by using intraclass correlation coefficient and Bland-Altman method.

RESULTS: In the walking task, the agreement is good to excellent for steps between the Nokia Go and the reference device. In the free-living condition, there is a systematic underestimation of steps in comparison with the ActiGraph. Excellent agreement was found between locations. The device worn at the hip indicated the lowest number of steps, and the device located at the dominant wrist indicated the greatest number of steps.

CONCLUSIONS: There are high discrepancies in step count between devices because of the different types of activities in daily life. The Nokia Go may be confidently used for step counting during pure walking tasks, at different locations. However, the lack of concurrent validity with ActiGraph call for caution regarding their use in daily living conditions.