Study finds activity trackers not as accurate for certain activities

activity trackers not accurateResearchers from Iowa State University (ISU) have uncovered that the use of activity trackers for some activities is not as accurate in comparison to others. Although they can provide a close estimate of calories burned, activities like strength training are not accurately measured.

Activity trackers – devices you either strap on your wrist or body – have rapidly flooded the market. With features that track step counting, heart rate and calories burned, they are used to measure one’s progress throughout the day in order to promote healthy living. A person can set a goal for themselves, and then monitor their progress to achieve that goal. With a variety of activity trackers on the market it is often difficult to pick the right one.


Previously, there have been doubts about activity trackers’ ability to be accurate, and although many companies have updated their systems, there is still some room for error.

For the testing, researchers at ISU compared the accuracy of four popular activity tracking devices: Fitbit Flex, Nike + Fuelband SE, Jawbone UP 24 and Misfit Shine. They were put through aerobic, sedentary and resistance activities to test accuracy. Two research monitors were also included: BodyMedia Core and Actigraph GT3X+.

Topping the list as the activity tracker with the least error (15.3 percent), was the BodyMedia Core. The least accurate device was the Misfit Shine.

Overall results of each device were:

BodyMedia Core15.3 percent
Actigraph GT3X+16.7 percent
Fitbit Flex16.8 percent
Nike+ FuelBand SE17.1 percent
Jawbone UP2418.2 percent
Misfit Shine30.4 percent

Conditions in which the activity trackers were tested under were intended to mimic real life activity. 56 participants completed 20 minutes of sedentary activity (reading, sitting, etc.), then 25 minutes of either aerobic or resistance exercise with a five minute rest in between.

Lead author Yang Bai said, “By looking at the most commonly performed activities in exercise and daily living settings, we can examine where the errors occur. As expected, some monitors overestimate or underestimate all three activities, but some monitors overestimate one type and underestimate the other two categories, which can cancel out if we don’t measure them separately.”


Fitness trackers, whether accurate or not, should promote motivation because improving the levels of physical activity is merely one part of the equation. As professor of kinesiology Greg Welk added, “I think the key to a consumer is not so much if the activity monitor is accurate in terms of calories, but whether it’s motivational for them and keeps them accountable for activity in a day.”

The findings were published in Medicine & Science in Sports & Exercise.


Author Bio

Devon Andre has been involved in the health and dietary supplement industry for a number of years. Devon has written extensively for Bel Marra Health. He has a Bachelor of Forensic Science from the University of Windsor, and went on to complete a Juris Doctor from the University of Pittsburgh. Devon is keenly aware of trends and new developments in the area of health and wellness. He embraces an active lifestyle combining diet, exercise and healthy choices. By working to inform readers of the options available to them, he hopes to improve their health and quality of life.