Article title: Validation of Fitbit-Flex as a measure of free-living physical activity in a community-based phase III cardiac rehabilitation population
Fitbit, the popular physical activity monitoring device, is a valid and reliable way of monitoring physical activity, finds this study. Whilst Fitbit-Flex is one of the most popular wearable devices currently available to measure physical activity, very little research has been conducted on its accuracy. The use of such devices also offers significant promise to researchers and clinicians working in cardiac rehabilitation program to evaluate, monitor and encourage physical activity that is integral to recovery.
In order to ascertain the reliability of Fitbit devices and evaluate their effectiveness for monitoring the physical activity of cardiac patients, the researchers evaluated 48 patients and family members participating in community-based exercise programmes. The 48 participants wore the device over four days to monitor daily step counts and minutes of moderate to vigorous physical activity (MVPA).
The researchers discovered that:
“Fitbit-Flex is a valid and reliable device for activity monitoring specific to predicted attainment of physical activity guideline recommendations (i.e. step counts and minutes of MVPA). It is also useful for monitoring physical activity in cardiac patients and for comparison among individuals. However, caution must be taken when using Fitbit-Flex for research purposes as it slightly over-estimates step counts and MVPA. Nonetheless, Fitbit-Flex is capable of continuously monitoring free-living conditions and for providing valuable physical activity data for clinicians, individuals and researchers to track physical activity levels.”
Background Accurate physical activity monitoring is important for cardiac patients. Novel activity monitoring devices may enable precise measurement of physical activity. This study aimed to validate Fitbit-Flex against Actigraph accelerometer for monitoring physical activity.
Design A validation study with a comparative design.Methods Cardiac patients and family members participating in community-based exercise programs wore Fitbit-Flex and Actigraph simultaneously over four days to monitor daily step counts and minutes of moderate to vigorous physical activity (MVPA).
Results Participants (N = 48) comprised 52.1% males, with a mean age of 65.6 ± 6.9 years and 58.9% had a cardiac diagnosis. Fitbit-Flex and Actigraph were significantly correlated in males, females, total participants and cardiac patients for step counts (r = .96; r = .95; r = .95; r = .95), though less so for MVPA (r = .81; r = .65, r = .74; r = .71). As step counts increased the differences between Fitbit-Flex and Actigraph also increased. Fitbit-Flex over-estimated step counts in females (556 steps/day), males (1462 steps/day) and total participants (1038 steps/day) as well as for minutes of MVPA in females (4 min/day), males (15 min/day) and total participants (10 min/day). Fitbit-Flex had high sensitivity and specificity in classifying participants who achieved the recommended physical activity guidelines.
Conclusion Fitbit-Flex is accurate in assessing attainment of physical activity guideline recommendations and is useful for monitoring physical activity in cardiac patients. The device does, however, slightly over-estimate step counts and MVPA.
Original scientific paper: Muaddi Alharbi,
Adrian Bauman, Lis Neubeck, and Robyn Gallagher
Validation of Fitbit-Flex as a measure of free-living physical activity in a community-based phase III cardiac rehabilitation population European Journal of Preventive Cardiology 2047487316634883, first published on February 23, 2016 doi:10.1177/2047487316634883