A friend of mine tries to calculate this, and I've googled about a lot to find a reasonable formula.
What we know is: gender = man, height = 1.80m, weight = 120kg, energy expenditure (VO2): 3.2 L/min, and time (cardio): 40 min.
I've found a few formulas on the internet that use the latter three, for example (From livestrong.com): cal = (METs * 3.5 * weight) / 200 * time
But I have no idea where they got 200 from. I've also found more simple ones: cal = METs * weight * time (hours)
But we should be able to derive calories directly from the energy expenditure (VO2), as this is - as I understand - proportional to calorie expenditure (?).
It seems like there are a million different formulas for the same thing. I've never understood how such a simple thing can be made this confusing. This is worse than my linear algebra in n'th dimensions in uni!!
Any ideas are greatly appreciated!