Workout Energy Listing -- What are the units?

When you are reviewing a workout under the name it lists the TSS, duration, iF, and work. The work value lists the units as “kJ(Cal)”. So it is a bit confusing, are those units kilojoules or kilocalories?

I am looking at Fletcher for instance and it lists 812 kJ(Cal) as the work value. Since kJ is the lead I assume kilojoules is the unit but when we convert that to kilocalories it seems unreasonably low in terms of dietary calories (ie kilocalories) – working out to a bit under 200 kilocalories. 812 kilocalories seems about right for a 1.5 hour session. Looking at the data from a Fletcher workout I performed last fall (in one of my many cycling apps) shows a calorie burn of 816 calories. So I assume the number is NOT kilojoules but kilocalories, correct?

As always I appreciate your comments, answers, and discussion. Thanks!

The human body thermodynamic efficiency is roughly 20% to 25%. To do 1 calorie’s worth of actual work, you need to burn roughly 4.

You’re correct that 800 kJ of work is equivalent to about 200 calories of work. It just so happens that you need to burn roughly 800 calories to do that amount of work, so in the end doing 1 kJ of work requires you to burn roughly 1 Calorie of energy. That’s why they list the same number with both units.


Thanks, given that 4 calories of human effort to generate 1 calorie of pedal work it now makes sense to me. I’m also glad that is the case, because I like to eat.