If that is an indirect measurement then what would you consider a direct measurement that would be practical for a cyclist? or even a runner?

It's not perfect, or maybe even great, but with a model that is tailored to each person you can get a good approximation. Basically, HR can't/shouldn't be the only input to the model, and I've acknowledged that from the beginning.

Per the question you ask, it doesn't seem obvious who is burning more calories, because there are a lot of pieces to the puzzle that you don't include, and I think that a good HR based software could take those into account and give decently accurate numbers. When you simply boil it down to his HR is XYZ, mine is PQR, who burns more calories, you're failing to acknowledge the other factors that go into the calculation.

Weight (helps account for work done moving mass against gravity)
Height (not sure of the need here)
Age (not sure of the need here)
Max HR (I assume this serves to help assess, relatively-speaking, how hard you're working)
Some measure of fitness level--Polar did it with "OwnCal" or "Owncalc" I believe, which was supposed to be analogous to VO2 max; Garmin does it with a 1-10 scale. Not a perfect system, but I imagine that including fitness level in the model tailoring helps increase the accuracy significantly.

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My whole argument is that there's no practical direct measurement, and that, among the indirect methods like HR and cycling power (I don't think you can disagree that they're indirect), HR (with qualifications/tailoring/etc) is probably better than rear wheel power in predicting calorie expenditure that might be measured with a direct method.

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Okay.

Me: 6'6, 185lbs, 29, Moderately Fit, Max HR 201

(I'll make up lance's stats)
Lance: 5'10, 150lbs, 34, Elite, Max HR 195

We're both going up a big hill.

My HR is 180
Lance's HR is 150

I'll even add some more data points:
It's 85 degrees outside.
We're at 4500 feet.
There is a 5mph head wind.
It's a Tuesday.

How many calories are we burning?

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CEO at TrainerRoad
Co-host of the Ask a Cycling Coach Podcast

I think that's what people are having problems with. You think HR is better than power for estimating calories burned.

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CEO at TrainerRoad
Co-host of the Ask a Cycling Coach Podcast

Still not getting it... It's actually funny to watch.

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If you each wore a Garmin it would sort that shit out for you! The calculation isn't as cut and dry as the cycling one because I'm sure there are some fairly complicated regression equations that map the %max HR and relative fitness aspects to calorie expenditure, based on the results of well-controlled, peer-reviewed studies, although evidence suggests that that may not be necessary.

The tailoring seems to be the important part, and if I had done the work to get that part right then I'd be selling HR watches right now instead of studying aerospace engineering.

The latter of the two articles I cite below supports the finding: "A combination of simple measurements and heart rate monitoring produces estimates of energy expenditure that are highly correlated with those obtained using full individual calibration. This simplification of the heart rate monitoring method could extend its use in ranking individuals in epidemiological studies."
The former seems to formally assess the relative importance of the tailoring/calibration of the model.


Assessment of the heart-rate method for determining energy
expenditure in man, using a whole-body calorimeter
B Y M. J. D A U N C E Y A N D W. P. T. J A M E S
M R C Dunn Calorimetry Group, A R C Institute of Animal Physiology,
Babraham, Cambridge CB2 4AT
(Received 24 July 1978 - Accepted 2 October 1978)


and

Estimating energy expenditure by heart-rate monitoring without individual calibration
[/url]
RENNIE, KIRSTEN L.; HENNINGS, SUSIE J.; MITCHELL, JO; WAREHAM, NICHOLAS J.

Med. Sci. Sports Exerc., Vol. 33, No. 6, 2001, pp. 939–945.

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Right. The power method relies on knowing GME. This uncertainty seems to me a glaring issue, but others readily accept a median value and move on. In a debate about the accuracy of a method I don't think it's fair to do this. Variability there is documented at 8%, compounded with any measurement errors associated with the PT itself (+/- 5%?). I guess I would have to show that HR could do better than that, which I am working on.

GME varies with a lot of things, though, right? I would imagine that it varies with cadence, power output, ambient conditions, etc. Do you know of anyone who has measured this?

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You need to be presenting arguments that show that HR is superior to kJ when estimating calories.


Here's another one for you, one that anyone who trains with HR can relate to.


Week1 - I ride indoors for 1 hour at 150 watts at avg HR of 140 bpm


Week2 - I ride indoors for 1 hour at 150 watts at avg HR of 150 bpm


Between these two weeks nothing has changed. Room temperature was the same, drive efficiency was the same, humidity was the same, cooling was the same my efficiency was the same.


Which one burned more calories, and if so how much?

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CEO at TrainerRoad
Co-host of the Ask a Cycling Coach Podcast

Yes, I agree with everything you said here.

GME would vary, the causes of this variation would spawn a even longer thread than this. Try posting "Which cadence is most efficient?" and watch the shit storm. I can't point to any studies that have measured this, but I've heard of ones that do.

EDIT: Cycleops says power taps are +/-1.5&

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CEO at TrainerRoad
Co-host of the Ask a Cycling Coach Podcast

Could your efficiency truly be the same in both examples. Something here is a dependant variable.

If you really want to know the truth keep looking and you will get there and at the end you will agree with Paulo because he is right.
HR is not even close to be one of the best measures for energy expenditure estimation.

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Hmm...well the temperature stuff relies on a delta T, so I think you have not ruled out the possibility of differences in starting/ending core/body temperature from one week to the next, so there isn't necessarily a major issue here.
Furthermore, you can't take it as a given that your cooling/efficiency were the same. Phenomena like what you described below are easily described by issues like gastric processes, which consume a non-negligible amount of energy.

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I don't know for sure. I think it could be though.

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CEO at TrainerRoad
Co-host of the Ask a Cycling Coach Podcast

I'm looking, but nobody is really working to provide evidence for the power method. People are simply poking holes in the HR method. I'm not opposed to accepting Paulo's conclusion, but I refuse to change my mind without being shown any evidence. Anyone?

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Paulo provides some of the most useful, insightful and knowledgeable posts on this forum. Unfortunately for many, they are heavily tinged with sarcasm and often include needling of some sort. I think you should get past that. Comparing him to Jason is ridiculous.

Check out my post about the kJ to calories math.

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CEO at TrainerRoad
Co-host of the Ask a Cycling Coach Podcast

I know neither poster, or you but this seems to be an oxymoron : ) And I am guilty as charged as well.

Hmmmm, 1,000,000 Calories a day sounds like a lot (that would be 1,000 Kilo Calories).

At roughly 3,000 calories per pound (as I recall), that would be 333 lost pounds. None of this is doable in a day. Even trying it over a year means you would have to decrease your intake by 2740 calories a day which is likely more than you are consuming. Although once you have starved yourself to death I suppose weight loss is pretty quick.

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BC Don
Pain is temporary, not giving it your all lasts all Winter.

???????????????????????


http://en.wikipedia.org/wiki/Calorie

3500 cal eq a pound
Food calories are measured in kcal
Kj eq kcal in most humans

I am learning the semantics argument in the main forum.

Your third statment is dead wrong : )

From my reading it's fairly obvious that PS and SeasonsChange agree with each other, if not overtly at least in the sense where they're both saying you're incorrect b/c of a certain issue. Also from my reading, it appears that they are saying that using a powermeter to measure calories is more accurate because of the fact that KJ (the amount of "work" measured by a powermeter, which if you had bought my powertap you'd be familiar with at this point ha) is roughly equal to kCal. So, in essence, it's not even equal to an estimation; it's a measurement of your expenditure.

I don't know enough about this subject to actually weigh in on it, but that's my take. Feel free (anyone) to tell me my "summary" is wrong.