Fitness Trackers Out of Step When Measuring Calories

Fitness devices can help monitor heart rate but are unreliable at keeping tabs on calories burned, research has revealed. Scientists put seven consumer devices through their paces, comparing their data with gold-standard laboratory measurements.

"We were pleasantly surprised at how well the heart rate did -- under many circumstances for most of the devices, they actually did really quite well," said Euan Ashley, professor of cardiovascular medicine at Stanford University and co-author of the research.

"At the same time we were unpleasantly surprised at how poor the calorie estimates were for the devices -- they were really all over the map."

The team tested seven wrist-worn wearable devices -- the Apple Watch, Basis Peak, Fitbit Surge, Microsoft Band, Mio Alpha 2, PulseOn, and Samsung Gear S2 -- with 31 women and 29 men each wearing multiple devices at a time while using treadmills to walk or run, cycling on exercise bikes or simply sitting.

"There were diversity of ages, male and female, and then also we looked at diversity of skin tone, and then size and weight to try and represent the population generally," said Ashley.

The resulting heart rate data and energy expenditure estimates for each device were then extracted and compared to data that had been collected simultaneously by "gold standard" laboratory-based measures: electrocardiograph (ECG) to measure heart rate, and indirect calorimetry -- a measure of oxygen and carbon dioxide in the breath -- to measure calories burned.

The results, published in the Journal of Personalised Medicine, reveal that overall the fitness trackers performed well at measuring heart rate. For all forms of exercise compared to the lab tests the most accurate readings were from the Apple Watch, which had a median error rate of 2%, while the Samsung Gear S2 came bottom of the pile with a median error in heart rate...

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Fitness Trackers Out of Step When Measuring Calories

Fitness devices can help monitor heart rate but are unreliable at keeping tabs on calories burned, research has revealed. Scientists put seven consumer devices through their paces, comparing their data with gold-standard laboratory measurements.

"We were pleasantly surprised at how well the heart rate did -- under many circumstances for most of the devices, they actually did really quite well," said Euan Ashley, professor of cardiovascular medicine at Stanford University and co-author of the research.

"At the same time we were unpleasantly surprised at how poor the calorie estimates were for the devices -- they were really all over the map."

The team tested seven wrist-worn wearable devices -- the Apple Watch, Basis Peak, Fitbit Surge, Microsoft Band, Mio Alpha 2, PulseOn, and Samsung Gear S2 -- with 31 women and 29 men each wearing multiple devices at a time while using treadmills to walk or run, cycling on exercise bikes or simply sitting.

"There were diversity of ages, male and female, and then also we looked at diversity of skin tone, and then size and weight to try and represent the population generally," said Ashley.

The resulting heart rate data and energy expenditure estimates for each device were then extracted and compared to data that had been collected simultaneously by "gold standard" laboratory-based measures: electrocardiograph (ECG) to measure heart rate, and indirect calorimetry -- a measure of oxygen and carbon dioxide in the breath -- to measure calories burned.

The results, published in the Journal of Personalised Medicine, reveal that overall the fitness trackers performed well at measuring heart rate. For all forms of exercise compared to the lab tests the most accurate readings were from the Apple Watch, which had a median error rate of 2%, while the Samsung Gear S2 came bottom of the pile with a median error in heart rate...

Comments are closed.