# Calorie calculation, data bars, MPA calculation

Three questions:

1. Your calculations of Calories burned yields results, in relation to kilojoules burned, which are very different from any other software program or estimating formula. Usually Calories are estimated at about 96% of kilojoules, yours turn out to be about 110% of kilojoules. What do you know no one else does?

2. When I look at Activity details, at the top of the data section there are 4 different color bars representing power. speed, cadence, HR with a number at each end. I know what the numbers represent but what is the significance of darker shading of part of each bar?

3. Are the MPA numbers at any point in my ride extracted and calculated based solely on my history, or are they based in large part on statistical data from a broad variety of riders? I consistently see MPAs at the end of hard efforts that are 200 to 400 watts higher than I know I could obtain. Is there a way, as with the Freshness Feedback slider, that I can adjust those curves to be more realistic?

Hello,
I’m not sure but it seems to me that the algorithm for calculating calories burned is also based on the intensity of the effort at a given moment, and it is not just a simple calculation of the output mechanical energy. It seems that the effectiveness of the effort varies depending on its intensity.

In my rides the Calorie/kj ratio is always the same whether it’s a hard effort or recovery ride, about 1.1 to 1.

Hi Ken, Excellent questions.

1. Your calculations of Calories burned yields results, in relation to kilojoules burned, which are very different from any other software program or estimating formula. Usually Calories are estimated at about 96% of kilojoules, yours turn out to be about 110% of kilojoules. What do you know no one else does?
Xert uses a lower gross efficiency than other software companies (who typically use 25%). Our assumption tends to align more with what the scientific literature suggests, though there still is inter-individual variability. This means that Xert will assume that you require more calories than other analytical platforms to perform the same amount of work. Additionally, our calculations don’t include basal metabolic demands, only the extra demands placed on the body by performing mechanical work. The model assumes the same GE for all efforts all along the PD curve.

2. When I look at Activity details, at the top of the data section there are 4 different color bars representing power. speed, cadence, HR with a number at each end. I kno w what the numbers represent but what is the significance of darker shading of part of each bar?
The darker shade represents the average value with respect to the peak value (the end of the bar).

3. Are the MPA numbers at any point in my ride extracted and calculated based solely on my history, or are they based in large part on statistical data from a broad variety of riders? I consistently see MPAs at the end of hard efforts that are 200 to 400 watts higher than I know I could obtain. Is there a way, as with the Freshness Feedback slider, that I can adjust those curves to be more realistic?
The MPA calculated for you on a ride is based only on your data. The model currently assumes that you’re able to hit your best numbers hours deep into a ride, which may be true of professional athletes, but we know intuitively is not the case for the vast majority of rides. For this reason, we’re working on developing a 4th fitness signature - “Endurance Energy”, which will help MPA track more accurately during prolonged cycling.

Hope this helps!