Originally Posted by
twobadfish
Then you don't have the right equipment.
He's got a power meter. That directly measures energy output and therefore calories burned.
That graph was sourced directly from Garmin.
And Garmin is not a disinterested party when the accuracy of their devices is the question.
You can see there are other types of HRM/Device setups which allow for a larger variation. This is the reason why everyone has different experiences with calorie measurement and Garmin devices. And also why there seems to be a deviation between Garmin devices and other manufacturers.
And guesstimating calories burned from how fast your heart is beating doesn't add to the accuracy, either.
It's not as simple as you are painting it.
And every bit of complexity adds to the inaccuracy.
I can find lots of rides in my history with nearly identical kJ but that have wildly different heart rates. Some days my HR won't go over 150 unless I really push and drops rapidly when I back off. Some days its up over 165 with no real effort and stays there forever. Some days it takes a while to get up there, but stays up.
Why would estimating calories burned from HR be any more accurate than using "220 - age" to specify someone's max heart rate?