Forum

How devices measure EE

Author Message

blue sky
Date sent: 2017/05/28 23:18:03
I am under the impression that devices derive energy expenditure from heart rate data when they have it and from steps when they don't. I believe they utilize a formula to convert heart rate into calories. Common formulas include as variables sex, age, weight, etc. If your study shows that heart rate measurement is fairly accurate and calories are not, shouldn't the conclusion be that the formulas used by the devices to translate heart rate into calories used are inaccurate? The devices don't measure energy expenditure. They measure heart rate and simply report formula derived energy expenditure. So improving the formula should improve the reporting of energy expenditure at least to the point that heart rate is a proxy for energy expenditure, and to the reliability of the heart reate measurement.

rongeorge
Date sent: 2017/07/19 08:22:44
I would hope that HR is not the sole surrogate used in the EE calculation, for if it was, on a normal 1 hour run in warm weather where your HR drifts upward naturally, would it mean that EE also increases?

rongeorge
Date sent: 2017/07/19 10:23:34
Also note : Studies say that in general, devices that measure EE using a dual strategy of HR + PA data through accelerometry are significantly more accurate than just HR alone. This makes sense. For example, a person sitting on a chair typing away at a computer or playing an instrument may not have a high heart rate but accelerometry data can correct for a low HR derived EE.