The popular wearable activity trackers to monitor physical activity and measuring steps may not be really effective in measuring sleep, according a new study. Consumer-wearable activity trackers are electronic devices used for monitoring fitness and other health-related metrics.
Researchers from the UNC Gillings School of Global Public Health and RTI International conducted a review the evidence for validity and reliability of popular consumer-wearable activity trackers (Fitbit and Jawbone) and their ability to estimate steps, distance, physical activity, energy expenditure, and sleep.
The research led by Dr Evenson and team surveyed 22 published articles to find out the accuracy of these activity tracker devices, as they are increasingly becoming popular among the health conscious.
Different studies indicated that the step counting feature was correct both in the lab as well as in the field. However, only one study evaluated the distance tracking for the Fitbit device and found that it tends to overvalue at slower speeds and undervalue at high speeds. Two studies compared accelerometry and evaluated physical activity and found high correlation (in Fitbits) in one study and observed a larger range in correlation between the Fitbit and Jawbone brands, in another study. Authors found that both tracker brands showed undervalued calories used and overvalued total sleep time.
Overall, based on several studies, the systematic review showed:
- Higher validity of step counting
- Undetermined findings for distance and physical activity;
- Lower validity for calories and sleep.
Researchers recommend few strategies for device wearers that may help them implement, to make the tracker monitor the activity more accurately. Recommendations include:
* To always wear the tracker in the same position every day.
*To iInsert personal details such as height and weight accurately at the first set-up, and update if there is any considerable change in the weight.
* If the tracker offers these options, then, correctly mark the length of a walking stride; incorporate more information through the device's journal function; and interact with the sleep mode settings.
Reference: Systematic review of the validity and reliability of consumer-wearable activity trackers. International Journal of Behavioral Nutrition and Physical Activity, 2015; RTI International. "Activity trackers are better at counting steps than measuring sleep."
