Be Your Personal Best

Victor De Vogeleer

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4 years ago

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Heart Rate to Calorie calculation

Hi, I was wondering which method is used and what is the implicit accuracy of the calorie calculation performed by the Smart Belt in the App/summaries/MyActivio.

Garmin uses an algorithm from Firstbeat Technologies that measures the time between heartbeats to compute the Metabolic equivalent of the performed activity that, in combination with the already available data (height, weight, age and sex), is converted via the BMR (standard Benedict equation) into an absolute measure for caloric output. With this algorithm an error of 10% is achievable.

thanks in advance, Victor

Official Answer
photo Employee
Magnus Posted 4 years ago

Unfortunately we will not be able to share anything more than it's based on the well-known Harris-Benedict equation with proprietary improvements. We don't use the beat-to-beat information. There are no official reports or studies on the accuracy of the calorie value provided.

However, more important is that we do not build our solutions around calories because it will never be correct. It takes more than just your age, gender, HR and beat-to-beat to be a true value. We only provide it as a "training score" to be able to compare the same exercise with the same load from day to day.

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Comments (2)


Dear @Magnus, thank you so much for your swift reply!

I agree that it takes more than only these factors to come up with an accurate calorie consumed estimation, but regarding non-invasive and non-laboratory techniques this will be your nr. 1 go to. Vo2max is not very practical.

Considering that you sell the smart belt as a product, should you at least not have an indicative value for the accuracy. Why else do you have different models with different prices?

The reason I ask so specifically is because I am trying to reduce the error margins on the difference between planned and measured weight changes by optimising dietary energy intake (for private use, not commercial).

photo Employee

The calorie calculation happens in the Activio app or at, it is not calculated in the Activio Smart Belt. You will get the same values by using the Standard Belt or the Smart Belt. The accuracy for the hearte rate measurement is 0-235 BPM +/- 1 BPM. The advantage of the Smart Belt is that it contain dual radios, it works with the Activio Systems and our proprietary radio protocol at the gym (group training) and alsos individual training with a smartphone and Bluetooth Smart. It can connect to other apps than the Activio app if desired.

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