Activity trackers can provide a good overall estimate of calories burned, but are less accurate when measuring certain activities, such as strength training.
For a new study, researchers tested four consumer fitness trackers—Fitbit Flex, Nike+ FuelBand SE, Jawbone UP 24, and Misfit Shine—to see how well they measured sedentary, aerobic, and resistance activity. Two research monitors—the BodyMedia Core and Actigraph GT3X+—were also included in the study.
Overall, the BodyMedia Core was the top performer with a rate of error of 15.3 percent. The Misfit Shine was the least accurate with a 30.4 percent error rate.
Accuracy isn’t everything
Published in the journal Medicine & Science in Sports & Exercise, the study was designed to mimic real daily living activities. The 56 participants were asked to complete 20 minutes of sedentary activity, such as reading a book, working at the computer, or watching a video. That was followed by 25 minutes of their choice of aerobic activity and 25 minutes of resistance exercise, with 5 minutes of rest between each activity.
“By looking at the most commonly performed activities in exercise and daily living settings, we can examine where the errors occur,” says Yang Bai, lead author and a graduate research assistant in kinesiology at Iowa State University.
“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.”
Researchers say accuracy is important, but it is only part of the equation in terms of improving physical activity levels.
“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,” says Greg Welk, professor of kinesiology.
Source: Iowa State University