Popular consumer fitness trackers such as Fitbit Flex, Nike+ FuelBand SE, Jawbone UP 24 and Misfit Shine may provide a good overall estimate of calories burned, but it is less accurate when measuring certain activities such as strength training, suggested a new study by researchers from the Iowa State University (ISU).
For the study, researchers tested 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 found to be the top performer with a rate of error of 15.3%. The Misfit Shine was the least accurate with a 30.4% error rate.
The research team designed the study to mimic real daily living activities. The 56 study participants were asked to complete 20 minutes of sedentary activity, such as reading a book, working at the computer or watching a video. This was followed by 25 minutes of their choice of aerobic activity and 25 minutes of resistance exercise, with five minutes of rest between every activity.
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."
The results were published in Medicine & Science in Sports & Exercise.