In June 2018 researchers from the UK published the results of their review of the scientific literature to assess the validity and reliability of commercial activity trackers in older, community-dwelling adults. A total of seven studies involving 290 adults (average age 70 years) with a range of medical conditions were included in the review. A total of eight different activity trackers had been evaluated. Results showed that the daily step count and activity duration recorded by all activity trackers were generally similar to that assessed by reference devices and validated assessment methods. However, it was noted that a slower walking pace and impaired walking reduced the levels of accuracy.
Straiton N et al. The validity and reliability of consumer-grade activity trackers in older, community-dwelling adults: A systematic review. Maturitas. 2018 Jun;112:85-93