Dr Rhys Thatcher, Reader in Exercise Physiology at the Institute of Biological, Environmental and Rural Sciences (IBERS) was commissioned by BBC One Wales’ X-Ray to test the Fitbit Charge 2, Letscom HR and Letsfit.
Working with 12 participants - 6 male and 6 female – Dr Thatcher and colleagues tested three top selling activity trackers; Fitbit Charge 2, Letscom HR and Letsfit.
The test participants walked on a treadmill for ten minutes at 4km per hour, followed by a ten minute jog at 8km per hour.
Using indirect calorimetry, the team were able to calculate the amount of oxygen used during activity.
Dr Rhys Thatcher said: “There is a direct relationship between the amount of energy somebody is using and the amount of oxygen they are burning. If you know how much oxygen you’ve burned, we can then know accurately how many calories you’ve expended throughout the activity.
“At the walking pace of 4 km the Letsfit had the closest agreement to the criterion measure over predicting calories by 2.6% followed by the Letscom HR which over predicted by 15.7% with the Fitbit having the largest difference of 53.5%.
“This differed to the 8km speed at which the Fitbit was the closest with a 4.3% underprediction followed by the Letscom HR and the Letsfit with 33.4% and 40.1% underpredictions respectively.
According to Dr Thatcher the accuracy of activity trackers was not that important when considering their health benefits.
The study will feature on BBC One Wales’ X-Ray on Monday 28 January 2019 at 7.30pm.