Increasingly popular wrist-worn fitness tracking bands may be underestimating our exercise levels by up to 40 percent, a new study has found.

The research took place at the University of Queensland (UQ) and sought to determine the accuracy of the popular fitness monitors. PhD student, Matthew Wallen and supervisor Professor Jeff Coombes from the UQ’s School of Human Movement and Nutrition Sciences led the study in testing the four most common devices.

Matthew Wallen said “None of the devices proved to be consistently more accurate overall and the percentage error for energy expenditure was between nine and 43 per cent. Measurement of heart rate was more accurate, with only minor variances.”

“Combining these two factors, it shows there are limits to how much trust we can place in such devices to monitor energy balance and therefore, to serve as weight loss aids.”

The study involved 22 participants with an even split of males and females. They each completed a variety of activities, which included running, cycling and walking as well as seated and laying rest. The variety of activities were carried out for approximately an hour at a time.

Every 15 seconds the measurements of fitness trackers were compared to electrocardiography readers. Then again against a portable gas analysis system which measured the number of calories burnt.

To follow the manufacturers’ instructions, each of the devices was tailored to reflect the user’s age, gender, height and weight.

“We did seek technical assistance from each company to learn information regarding the algorithms used by each device to determine energy expenditure. However, this information was not disclosed.” Matthew Wallen added.

Other collaborators on the study were Dr Shelley Keating and Dr Sjaan Gomersall of UQ, and Professor Ulrik Wisloff of the Norwegian University of Science and Technology.

Source: PLOS One