# Training & Nutrition - Calculation of Calories Burnt Using Heart Rate

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Snuffleupagus
10-10-06, 05:08 PM
I have been scouring Google to no avail in an attempt to find a calculator that allows me to estimate calories burnt using my average heart rate over a given time.

Something that takes into account age/height/weight/resting hr would be perfect...

Thanks for the help!

SSP
10-10-06, 05:28 PM
I have been scouring Google to no avail in an attempt to find a calculator that allows me to estimate calories burnt using my average heart rate over a given time.

Something that takes into account age/height/weight/resting hr would be perfect...

Thanks for the help!

AFAIK, there's no standard formula for that. Each of the manufacturers use their own proprietary algorithms to estimate "metabolic equivalent (METS)" based on heart rate. They then take what they know about you (including gender, height, weight, etc.) and determine your basal metabolic rate. They then, presumably, multiple your basal rate by your METS to determine calories burned per hour.

FWIW, for road riding a good rule of thumb is 40 calories per mile.

grebletie
10-10-06, 08:30 PM
AFAIK, there's no standard formula for that. Each of the manufacturers use their own proprietary algorithms to estimate "metabolic equivalent (METS)" based on heart rate. They then take what they know about you (including gender, height, weight, etc.) and determine your basal metabolic rate. They then, presumably, multiple your basal rate by your METS to determine calories burned per hour.

FWIW, for road riding a good rule of thumb is 40 calories per mile.

That's what has always bugged me about my HRM, it doesn't have anywhere to enter age, height, weight - anything. Consequently, I take what it tells me with a huge grain of salt.

GilmourRacer
10-10-06, 09:01 PM
caloriesperhour.com

SSP
10-10-06, 09:29 PM
That's what has always bugged me about my HRM, it doesn't have anywhere to enter age, height, weight - anything. Consequently, I take what it tells me with a huge grain of salt.

Yep...the ones that don't take such things into account are making some assumptions about "average metabolic rate". They might be reasonable if you're near the average, but whether you're a 250lb 25 year old guy, or a 105 lb 70 year old woman, they assume the same metabolic rate for both.

Most of the HRM's on gym equipment are like that...in fact, I suspect that some manufacturer's intentionally bias their "calories burned" estimates towards the high side. That way, users will feel good about themselves for burning "800 calories per hour" while they're jogging on a treadmill at a 10 min/mile pace :rolleyes:.

DannoXYZ
10-11-06, 05:27 PM
Yeah, there's no formulae because there's too many other variables besides just HR. The muscular efficiency is something that's hard to analyze without a real wattage-measurement device on your crank/rear-wheel and a gas-analyzer to capture your exhaled breath. A top-athlete like Olympic & TDF guys riding at 170bpm are going to be burning off a lot more calories and generating way more wattage than a weekend-warrior at the same HR. I'd say 35-45 calories/mile is a good estimate depending upon your position on the bike, weight, speed & terrain.

SSP
10-11-06, 05:36 PM
The muscular efficiency is something that's hard to analyze without a real wattage-measurement device on your crank.

That sounds really painful. :eek:

Metaluna
10-11-06, 06:02 PM
This thread gives formulas that might or might not be similar to what Polar uses:

http://forums.motionbased.com/smf/index.php?topic=2109.0

They take into account age, gender, weight, heart rate, and V02Max

Snuffleupagus
10-11-06, 06:55 PM
This thread gives formulas that might or might not be similar to what Polar uses:

http://forums.motionbased.com/smf/index.php?topic=2109.0

They take into account age, gender, weight, heart rate, and V02Max

Cool! That's the best thing I've seen thus far.

Here is a synopsis for anyone else looking:

OK I did some searching on the net and found a paper titled "Prediction of energy expenditure from heart rate monitoring during submaximal exercise" by L. R. KEYTEL, J. H. GOEDECKE, T. D. NOAKES, H. HIILOSKORPI, R. LAUKKANEN, L. VAN DER MERWE, & E. V. LAMBERT that was published in the Journal of Sports Sciences. I also found that Polar cites this paper as a source for their OwnCal(TM) calculation. They also cite a bunch of other studies. The formula for calculating energy expenditure in this article uses all of the factors that Polar says they use. So this may or may not be the formula they are using. Here are the formulas adjusted to Calories and separated into gender specific formulas:

Using VO2max
Men: C/min = (-59.3954 + (-36.3781 + 0.271 x age + 0.394 x weight + 0.404 x VO2max + 0.634 x HR))/4.184
Women: C/min = (-59.3954 + (0.274 x age + 0.103 x weight + 0.380 x VO2max + 0.450 x HR)) / 4.184

Without VO2max
Men: C/min = (-55.0969 + 0.6309 x HR + 0.1988 x weight + 0.2017 x age) / 4.184
Women: C/min = (-20.4022 + 0.4472 x HR - 0.1263 x weight + 0.074 x age) / 4.184
weight is in kg

DannoXYZ
10-11-06, 07:30 PM
Ahh... I see. So they narrow down the unknowns by having you make some real-world measurements like VO2-max. Cool... Is that VO2-max relative or absolute in the equation?

Richard Cranium
10-12-06, 10:03 AM
Many of the HR monitors do a pretty good job. But, I assume you understand that any HR based measure of metabolic expenditure cannot account for the anaerobic expenditure of energy substrates.

Using known Max HR, and estimated relationships between Max HR, body composition and anaerobic thresholds, weight, gender and age is about as close as anyone can get. HR monitors can be very accurate if you exercise at a steady rate AND at intensities below anaerobic threshold.

As a side note, none of the "calorie estimators" have the capacity to account for the contributions of glycogen stores to total caloric expenditures. There is simply no way to do it.

Induray
10-12-06, 10:28 AM
That sounds really painful. :eek:

He He:D You dog.

I try to keep my power meter always on the high side!

Greg180
10-12-06, 12:10 PM
Without VO2max
Men: C/min = (-55.0969 + 0.6309 x HR + 0.1988 x weight + 0.2017 x age) / 4.184

I must have my calculations wrong. At 45 yo, 190 pounds with an avg hr 145. This is -1881.3 c/min?

Care to review my calculations...(((-55.0969 + 0.6309) x 145) + (0.1988 x 86.18255) + (0.2017 x 45)) / 4.184

supcom
10-12-06, 12:21 PM
I must have my calculations wrong. At 45 yo, 190 pounds with an avg hr 145. This is -1881.3 c/min?

Care to review my calculations...(((-55.0969 + 0.6309) x 145) + (0.1988 x 86.18255) + (0.2017 x 45)) / 4.184

Grouping the first two terms together before multiplying by 145 is an error. the 145 term should be multiplied by 0.6309 only.

Greg180
10-12-06, 12:33 PM
Grouping the first two terms together before multiplying by 145 is an error. the 145 term should be multiplied by 0.6309 only.

So......((-55.0969 + (0.6309 x 145) + (0.1988 x 86.18255) + (0.2017 x 45)) / 4.184

is the correct equation?

Greg180
10-12-06, 12:41 PM
Mr Excel says that given the aforementioned parameters I am burning 14.96 (call it 15) calories per minute or 45 calories per mile. (20MPH AVG)

Correct?

If so my 302 Edge is off by 200 calories for an one hour bike ride.

10-12-06, 01:15 PM
Unless you stuff yourself into a bomb calorimeter, you cannot accurately know your calorie expenditure. It is all relative and just a number to give you a round about idea.

grebletie
10-12-06, 01:18 PM
Are the caloric requirements roughly the same on an indoor trainer, as long as the individual is at a similar heart rate for a similar time as outdoors? Since wind isn't a factor, I would assume not. But then you're likely making up the difference in force with the resistence being a bit higher to compensate for no wind.

Greg180
10-12-06, 01:26 PM
Unless you stuff yourself into a bomb calorimeter, you cannot accurately know your calorie expenditure. It is all relative and just a number to give you a round about idea.

Agreed. The only benefit of knowing "probable" calorie consumption is when you need to replace calories or when monitoring your caloric intake.

merlinextraligh
10-12-06, 01:38 PM
my experience is that the calculations of my Sigma HRM are dramatically higher than from my Powertap. Typical flat century ride might be something like 3000KJ(essentially equivalent to dietary calories, due the inefficiency in converting dietary calories to energy) , while the HRM will tell me I burnt 5000-6000 calories.

While you can argue about the percentage of dietary calories converted to KJ, the powertap is at least measuring actual energy produced. I tend to trust the Powertap numbers a lot more than calcualtions from a HRM.

jon10461
10-13-06, 04:28 PM
I hate to say this, but I agree wtih Merlin.
Think about it this way-compare Lance Armstrong with your average recreational rider (say, me)
If we both ride at 180 bpm, I am probably going 22mph on the flats. He is going like 30, and putting out a ton more watts than I am. So if we both ride for an hour, he has done a ton more mechanical work (which physics says is watts* length of time), which translates to more calories burnt. Thus, any heart rate monitor that tells you how much calories you burn can't be accurate since it doesn't take into account your heart rate. Now Polar gets around this in the OwnCal system which uses a much more complicated formula than the one above. The actually measure your heart rate variability, which they claim is a measure of your overall cardiovascular fitness and factor this into their calculation-i.e. the more fit you are, the more watts you'll put out at a given heart rate and the more calories you'll burn. This is the OwnIndex that the machine puts out.
The only way to truly know how much mechanical work you do on a ride is with a power meter.

keyone
05-06-08, 08:39 PM
I know this post is kinda old, but I thought I'd give it a shot and ask where you got that formula from?

I found these formulas by searching google, and created a nifty javascript calculator for my website. A website user pointed out that the higher a woman's weight is, the less calories she burns, so a 600 lb woman would burn zero calories when she works out. (this is for the female without VO2max calcs)

If you compare the male and female formulas, you can see that the male formula "adds" to the final value based on weight, whereas the female formula "subtracts".

Without VO2max
Men: C/min = (-55.0969 + 0.6309 x HR + 0.1988 x weight + 0.2017 x age) / 4.184
Women: C/min = (-20.4022 + 0.4472 x HR - 0.1263 x weight + 0.074 x age) / 4.184
weight is in kg

I am wondering if this is a typo, and really the female formula should be changed to say + 0.1263 x weight

Any ideas?

mt.andrew
05-11-08, 09:30 PM
just buy a suunto t3 that what I did, it also doubles as a bike computer with a POD