Fitbits goes the distance in the running study

Denise Jones, Joanne Kemp and colleagues at La Trobe Sports and Exercise Medicine tested the precision of Fitbit Flex for mid-to-high speed recording with the help of a group of Melbourne runners.

Dr. Joanne Kemp said that the study found that non-elite athletes could rely on the device.

"The Fitbit Flex is one of the most popular and affordable fitness equipment on the market and many runners use it to record their races," said Dr. Kemp.

"Previous research had shown that at lower speeds, Fitbits tended to underestimate the number of steps, but little research was done to determine their ability to measure operating speeds greater than 8 km. / h.

"Our study found that the Fitbit Flex has good to excellent reliability for rotational speeds between 8 and 14 km / h, but that it is slightly less reliable at higher speeds."

To test the accuracy of the Fitbit Flex, participants wore two Fitbits in the right arm and one in the left arm while running on a treadmill.

The researchers filmed them every four minutes, starting at 8 km / h. Speeds increased by 2 km / h after each interval and participants continued until they could not complete a full interval.

Mr. Kemp stated that there was a difference of less than 1% between the steps recorded by the Fitbits and the slow-motion video counting of the video recording steps.

"Between 8 and 14 km / h, the Fitbit Flex had come out about seven steps, a difference of less than one percent," said Dr. Kemp.

"We can say with confidence that they accurately measure the number of steps at the speed of jogging and running.

"However, it is difficult to assess their reliability at higher speeds because only a handful of our participants were able to continue operating at 16 km / h.

Additional research with a larger group of runners at this level is required. "

According to Dr. Kemp, the researchers also compared each of the three Fitbits worn by the participants and found differences ranging from two to six percent between devices worn on different arms.

"For those who want consistent recordings, our advice is to always wear your Fitbit on the same arm," said Dr. Kemp.

"Although Fitbits are not 100% accurate, it's good to know that they are a reliable way to track physical activity.

"Knowing that it will encourage riders to continue to train and even motivate others to start."

The research is in International Journal of Sports Physiotherapy.

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More information:
Denise Jones et al, VALIDITY AND RELIABILITY OF FITBIT FLEX ™ AND ACTIGRAPHE GT3X + AT JOGGING AND RACE SPEEDS, International Journal of Sports Physiotherapy (2018). DOI: 10.26603 / ijspt20180860