Reading a recent report on how accurate five activity trackers are, compared to actual readings taken using reliable scientific methods, the top device came out as the Jawbone.
The five trackers used in the study were Nike + Fuelband, Fitbit Ultra, Jawbone UP, BodyMedia FitCore and Adidas MiCoach. All these track steps taken and calories burned. During walking and running tests, elliptical cross training, and sports specific agility drills participants wore one of the activity trackers along with a portable metabolic analyser and a pedometer with proven reliability for comparison.
The results showed that all the trackers were 90-100% accurate for measuring steps taken during running and walking (the Jawbone being the most accurate) but less accurate during cross training and agility drills, and not very accurate at measuring calories used, probably due to biological variability.
What could be most beneficial for wearers of activity trackers is the prompt to be more active during the whole day. Some studies have shown people to be 30-40% more active during the day when wearing such a device.
Activity trackers are useful then as an accurate measure of steps taken whilst walking or running, and for encouraging more daily activity, but not advisable for counting calories expended. So, if you are expecting one from Santa this year be aware of its possible limitations.