Is my HRM giving me incorrect calorie burn?

EvgeniZyntx

Without all the technical knowlege, I expect that the HRM would be a *decent* estimate of calories burned durning exercise. So, I usually drop about 10-15% of the calories it said I burned when I log. Keeps me on my toes!

Well, there's the rub, if you are using a Polar FT4 or FT7 or other that has no VO2max stat, the HRM is actually underestimating your calorie burn. Because you can be very aerobically fit and overweight.

Thanks for posting those links, I'll likely read them over the wknd.
Have you taken a look at % error - are we talking about 5% or 50%?

But given that VO2max SS also varies (mine went up 50% in a two year period when I was 22 from 55 to 79!) over time, altitude, etc... Are we not missing the forest for the trees? An HRM underestimate would just result in a less calories being consumed. So a bit more weight loss. TDEE, BMR are also just estimates, as are the calories in a "steak" of x grams, as is the bio absorption. This is useful information, but I think in the end we always have to fiddle around.

On an HRM without VO2 one can just set the age lower or weight higher to increase the estimated burn.
I see a spreadsheet in my future.

It would be great to build out where the possible major errors might be these calcs by percent and probable spread in a population.
Thanks for the food for though.

heybales

Without all the technical knowlege, I expect that the HRM would be a *decent* estimate of calories burned durning exercise. So, I usually drop about 10-15% of the calories it said I burned when I log. Keeps me on my toes!

Well, there's the rub, if you are using a Polar FT4 or FT7 or other that has no VO2max stat, the HRM is actually underestimating your calorie burn. Because you can be very aerobically fit and overweight.

Thanks for posting those links, I'll likely read them over the wknd.
Have you taken a look at % error - are we talking about 5% or 50%?

But given that VO2max SS also varies (mine went up 50% in a two year period when I was 22 from 55 to 79!) over time, altitude, etc... Are we not missing the forest for the trees? An HRM underestimate would just result in a less calories being consumed. So a bit more weight loss. TDEE, BMR are also just estimates, as are the calories in a "steak" of x grams, as is the bio absorption. This is useful information, but I think in the end we always have to fiddle around.

On an HRM without VO2 one can just set the age lower or weight higher to increase the estimated burn.
I see a spreadsheet in my future.

It would be great to build out where the possible major errors might be these calcs by percent and probable spread in a population.
Thanks for the food for though.

All very true. So many take the HRM as stated fact, just wanted to share some insight.

One study on the Polar HRM using default values of HRmax and VO2max found the women up to 33% inflated burns, men lucked out down around 4%.
With correction, women down to 12%, men the same.

http://www.myfitnesspal.com/topics/show/459580-polar-hrm-calorie-burn-estimate-accuracy-study

Might as well mess with a spreadsheet that already has some formula's in it.
This includes a Polar funded study formula that incorporate VO2max, and table at the bottom that uses that and HRmax.
So you can play with all the figures to see how big or little the differences are.

http://www.myfitnesspal.com/topics/show/750920-spreadsheet-for-bmr-tdee-deficit-macro-calcs-hrm-zones

bsharrah

This is exactly why I no longer use a HRM, and just roll my eyes when I read posts after posts how people praise the accuracy of their Polar, FitBit, or BodyBugg. I don't worry about how many calories I burned doing whatever exercise, and certainly could care less how many I burned mowing the lawn. I would never consider eating back exercise calories because the entire practice is based on a lie. That lie being that you can somehow measure how many calories you are burning in the first place.

Figure out your TDEE as best you can using an honest daily activity level, reduce your calorie intake by a certain amount, then, over a few weeks, see how you feel, how much you are losing, and adjust accordingly. It isn't rocket science and you certainly do not need to become a slave to some device that should come with the disclaimer "for entertainment purposes only". IMO, way too many sheep are just assuming their devices or apps are accurate, and are blindly eating those calories back.

I saw this thread yesterday and found it comical that it had no responses. I have seen similar posts go by the way side with few responses in the past. I think it is because there are a lot of people out there who do not want to believe it and just choose to ignore this kind of information. Too many people "need" to know what they are burning, just as much as they need to know exactly what they are consuming. To many, it is an obsession, and many will never accept the fact that they are not going to accurately know what they burn, EVER!

heybales

This is exactly why I no longer use a HRM, and just roll my eyes when I read posts after posts how people praise the accuracy of their Polar, FitBit, or BodyBugg. I don't worry about how many calories I burned doing whatever exercise, and certainly could care less how many I burned mowing the lawn. I would never consider eating back exercise calories because the entire practice is based on a lie. That lie being that you can somehow measure how many calories you are burning in the first place.

Figure out your TDEE as best you can using an honest daily activity level, reduce your calorie intake by a certain amount, then, over a few weeks, see how you feel, how much you are losing, and adjust accordingly. It isn't rocket science and you certainly do not need to become a slave to some device that should come with the disclaimer "for entertainment purposes only". IMO, way too many sheep are just assuming their devices or apps are accurate, and are blindly eating those calories back.

I saw this thread yesterday and found it comical that it had no responses. I have seen similar posts go by the way side with few responses in the past. I think it is because there are a lot of people out there who do not want to believe it and just choose to ignore this kind of information. Too many people "need" to know what they are burning, just as much as they need to know exactly what they are consuming. To many, it is an obsession, and many will never accept the fact that they are not going to accurately know what they burn, EVER!

Have you ever wondered why a site like MFP, to help with diet and weight control and eating food, is setup to use food as a reward actually for having done exercise?

I'm starting to find that strange.

It seems like anything, setup exactly as you say with with goal workouts in there, and then ding you the few calories if you don't get the workout in.

jasonheyd

I think it's all generally helpful in terms of establishing guidelines / guard-rails, and helping people to be conscious of what they're doing -- both in terms of what they're eating, as well as in terms of how active they are.

In general, that's how I treat the calories-in and calorie-out estimates -- after all, even the calorie values of the foods are nothing but estimates -- but I do use the HRM to help me target specific "zones" during exercise.

Just means to an end. Some people find them useful, some people don't need them, but a better understanding of the tools' strengths & weaknesses is never a bad thing.

heybales

I think it's all generally helpful in terms of establishing guidelines / guard-rails, and helping people to be conscious of what they're doing -- both in terms of what they're eating, as well as in terms of how active they are.

In general, that's how I treat the calories-in and calorie-out estimates -- after all, even the calorie values of the foods are nothing but estimates -- but I do use the HRM to help me target specific "zones" during exercise.

Just means to an end. Some people find them useful, some people don't need them, but a better understanding of the tools' strengths & weaknesses is never a bad thing.

That is a great way of looking at it.

Just as when you are working on your car and something needs to be hammered in, anything within reach may do the job, but better be real careful if it's your light!

MDamoun

Bump

3dogsrunning

Bump for all those who are trying out their new presents.

heybales

Very true, might as well take some early workout sessions and figure out how close it is to accurate estimate.

PrincessNikkiBoo

save for later

donnam40

Isn't all of this just estimates anyway - exercise and food? What are the chances of that piece of chicken you eat being exactly the same composition as the one used to determine the calorie content? Pretty slim I think. HRM can be a great tool to estimate, just as the food diary here is a great tool to estimate. As long as it is understood that none of the figures (including calories consumed in the food diary) are exact and there is generally a defecit from TDEE, results should be seen.

aliciab307

This is interesting info.
I recently got a HRM for an estimate of how many calories expended since I do workout videos like Insanity, Les Mills, etc.

So just to make sure I am understanding this and the study correctly, the HRM needs to be running a few minutes before the actual work out?

Below you stated that the HRM isn't valid for calorie burns for intervals, in Insanity there are interval training programs. Do you believe that the estimate would be really off? The greatest interval is the stretch after the "warm up".

Now you know why the HRM isn't valid for estimating calorie burns wearing all day, nor for intervals, nor for lifting.

For a correctly setup HRM, the best estimate of calorie burn can only occur in steady-state aerobic exercise between a low-level exercise up to lactate threshold range, probably 90 - 150 or tad higher depending on fitness level.

And even then, the more fit you are, the more inaccurate it will be if there is no adjustable VO2max stat to be changed.

So to the HRM users, check those weights when you lose, and update those VO2max with self-test every so often.

heybales

This is interesting info.
I recently got a HRM for an estimate of how many calories expended since I do workout videos like Insanity, Les Mills, etc.

So just to make sure I am understanding this and the study correctly, the HRM needs to be running a few minutes before the actual work out?

Below you stated that the HRM isn't valid for calorie burns for intervals, in Insanity there are interval training programs. Do you believe that the estimate would be really off? The greatest interval is the stretch after the "warm up".

Having the HRM running for a bit doesn't matter. Steady-state refers to the HR being steady for 3-5 min.

So if it's spiking up, recovering back down, back up, down, ect - not steady state, intervals or lifting likely. And invalid.

It's one thing to be jogging and you slow on a hill, but HR still goes up by 3-5 bpm until you go level or down over the course of many minutes. But to jump 30-50 bpm in 30 -60 seconds, ya, not steady-state.

The Insanity program is especially bad. They claim it is intervals turned upside down. Meaning you run at a super high level and rest briefly.

Because the straight line correlation between HR and VO2 used and therefore calories burned, is only valid for aerobic, so about 90 bpm, up to where your lactate threshold is, 150-175. Beyond that point going higher, even if steady at that point, the line is no longer straight but evens out.

And from Insanity description, you are in the Anaerobic zone, below and above the lactate threshold, so really inflated the whole time.

heybales

Forgot to put in my last test during a recent aerobic base building Spin class.
So really steady-state.

2 Polar watches running off 1 chest strap. FT7 and RS300X.
All stats matched between them, gender, age, height, weight, HRmax from test, with the RS300X having the additional stat of Resting HR, and VO2max from actual VO2max test, and athlete level Top.
The RS300X Own-Index self-test actually was within 2 points of tested, so I was impressed. But I still used actual tested known value.

Average HR - 143 (66% of HRmax), Max HR - 158 (76% of HRmax). Barely above Active Recovery HR zone, peaking to top of Aerobic zone, so holding back a lot.
54 min.
FT7 - 595 calories
RS300X - 739 calories

Using the results of the actual VO2max test for that avgHR - 798.

So the cheaper Polar with no VO2max stat was under by 203 calories in the space of 54 min, or 225 cal/hr. At a pretty low HR actually. 4 hrs of cardio a week, I'd be under-estimated by 900 calories.

So the better Polar with VO2max stat was under by 59 calories in 54 min, or 66 cal/hr. 4 hrs a week would be 264 under real burn.

225 cal an hr under-estimate is prettty significant if you are trying to feed your workouts correctly for good performance, and don't want to increase your deficit beyond a reasonable amount.

Markguns

I think it's all generally helpful in terms of establishing guidelines / guard-rails, and helping people to be conscious of what they're doing -- both in terms of what they're eating, as well as in terms of how active they are.

In general, that's how I treat the calories-in and calorie-out estimates -- after all, even the calorie values of the foods are nothing but estimates -- but I do use the HRM to help me target specific "zones" during exercise.

Just means to an end. Some people find them useful, some people don't need them, but a better understanding of the tools' strengths & weaknesses is never a bad thing.

Exactly more data and a good tool to use.... also a valuable "positive feedback", you have visual record (mine downloads to PC, has selections of activities to match to the HR data, has graphs, etc.) so I can see progress! I use a Beurer PM62 Heart Rate Monitor only $60. Also transmits to cardio equipment display, so I get constant HR feedback. I don't have to hold those handles. If you don't want a HRM monitor don't buy it. It is all an estimate game anyway. This just gives you another tool to compare data to. More data is not a bad thing.

HallerFitness

THis is the best thread I've ever read on MFP.

raven56706

so which HRM is a good one to get?

heybales

so which HRM is a good one to get?

Polar seems to spend the most on their own studies. So Polar that has the VO2max stat, usually they have self-test too, and though some studies have shown that to be not great, at least gets you close, or able to enter your own stat.

The cheapest I've seen with that stat is RS300X.

Garmin's use a Firstbeat algorithm for estimating VO2max that fared well in a couple studies, but on mine you can't change the stat, which is a bummer. But that also means it keeps adjusting as you use it, becoming more accurate.

Suunto versions that have the stat are pricey, but come with many features people like. Never seen their name associated with a study though. Could have missed it, or they keep their data private I suppose.

3dogsrunning

Bump

Azdak

A lot of those factors are why I like the Digifit app for my iPhone (used with a Polar H7 HRM).

Digifit has fitness assessments built in for determining personalized heart rate zones, as well as VO2 max, and then uses those assessments to help estimate calorie burn.

It's still an estimate of course, but it should increase the accuracy as long as the assessments are updated from time to time.

http://www.digifit.com/ if anyone's interested... and no, I don't work for them. :-)

Don't know all the details about all of the new trackers, or of the particular "assessments" you describe, but I do know a lot about fitness assessments in general, and I suspect they are subject to the same limitations as HRMs.

The main issue is the inherent variability in heart rate response and other physiologic responses to activity. There is just no way to account for it completely.