How Does Spivi® Compute Burned Calories? – Spivi

Spivi® uses a chain of ordered methods to get the most accurate results of burned calories.
It starts with the first method and continues to the next one if value wasn’t computed. If the method succeeded Spivi® uses the returned value to display the burned calories.

Hardware based method
Some fitness equipment devices such as the Kieser M3i provide their computed burned calories. In that case Spivi® will use this direct value for displaying the burned calories.
Power based method
Any bike with power console that transmit it out will fit to this method. Blade ION, Schwin AC Perfomance w/MPower Console, FreeMotion etc.
The output power in Watts is converted to Energy in KJ units and the KJ units are converted to calories in KCal units using the direct conversion factor of 4.184. Since the human body is just about 20-25% efficient it actually expends 4-5 times the direct measured energy.
Spivi® uses a value of 4.75 for the human body efficiency factor.
Example: 500 KJ would be ~120 Kcal, applying the human efficiency factor of 4.75 results in with ~570 KCal.
Heart rate based method
In case a trainee wears compatible heart rate strap that is paired with Spivi® the system uses personal information such as Age, Gender and Weight and combine it with the actual measured heart rate to convert it to estimated burned calories.
METS based method
Using the Metabolic Equivalent of Task (MET) to convert available Cadence/Speed data to burned calories.

The most accurate way to compute burned calories in a workout is by measuring power output in Watts units and use a standard value to estimate the human body efficiency.
The next best accurate method is to measure heart rate in BPM units and combine it with member’s Age, Gender and Weight.
When both of the above inputs are not available a rough estimation of burned calories can be done using the Metabolic Equivalent of Task , a.k.a MET Table.

Check out this great article that explains in detail the accuracy level of each method.

It is important to understand that in any case the displayed burned calories is only an estimation.
Fully accurate computation depends on additional personal factors such as body work efficiency, VO2 Max and metabolic rate which are hard and expensive to determine while having great influence on the pace our body burns calories.

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