Is my HRM giving me incorrect calorie burn?
heybales
Posts: 18,842 Member
Sure, what are the things that could effect this possibly decent correlation between HR and calorie burn?
Limitations of Heart Rate Monitoring
However, assessing PA (Physical Activity) based on HR data has some inherent limitations that must be acknowledged:
• Established relationships between HR and AEE (Activity Energy Expenditure) are lacking for many lifestyle activities.
• The linear HR vs. VO2 relationship applies to moderate-intensity activity but is nearly a flat slope during low-intensity activity, resulting in a low correlation between HR and EE (Energy Expenditure) during sedentary and low-intensity activities.
• Due to inter-individual variability HRM data is best applied to groups.
• Numerous confounding factors affect the HR response to PA and therefore the HR vs. VO2 relationship.
These include high ambient temperature or humidity, time of day, emotional state/stress, fatigue, hydration status, food, caffeine and nicotine intake, previous PA, illness, body position, mode of exercise and use of limbs.
• Training status will also affect HRM data, as a less fit individual will elicit a higher HR than a more fit individual at any given VO2.
• Changes in work rates require a 3-5 minute adaptation period for the HR response to stabilize at that exercise intensity. Therefore, the exercise test protocol must allow sufficient time for the HR to reach steady state.
• HR monitors are subject to electrical interference (i.e. computers, hairdryers, car engines, etc) which result in either spurious high or low values or momentary loss of data, and the affected data needs to be either removed or replaced by the mean of the surrounding HR values.
If you want to read the studies those references are pointing to, Page 36 in the following study.
https://researchspace.auckland.ac.nz/bitstream/handle/2292/305/02whole.pdf?sequence=9
Page 32 has nice comments and studies on the motion sensor devices (BodyMedia & FitBit) for free-living calorie estimates.
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.
Limitations of Heart Rate Monitoring
However, assessing PA (Physical Activity) based on HR data has some inherent limitations that must be acknowledged:
• Established relationships between HR and AEE (Activity Energy Expenditure) are lacking for many lifestyle activities.
• The linear HR vs. VO2 relationship applies to moderate-intensity activity but is nearly a flat slope during low-intensity activity, resulting in a low correlation between HR and EE (Energy Expenditure) during sedentary and low-intensity activities.
• Due to inter-individual variability HRM data is best applied to groups.
• Numerous confounding factors affect the HR response to PA and therefore the HR vs. VO2 relationship.
These include high ambient temperature or humidity, time of day, emotional state/stress, fatigue, hydration status, food, caffeine and nicotine intake, previous PA, illness, body position, mode of exercise and use of limbs.
• Training status will also affect HRM data, as a less fit individual will elicit a higher HR than a more fit individual at any given VO2.
• Changes in work rates require a 3-5 minute adaptation period for the HR response to stabilize at that exercise intensity. Therefore, the exercise test protocol must allow sufficient time for the HR to reach steady state.
• HR monitors are subject to electrical interference (i.e. computers, hairdryers, car engines, etc) which result in either spurious high or low values or momentary loss of data, and the affected data needs to be either removed or replaced by the mean of the surrounding HR values.
If you want to read the studies those references are pointing to, Page 36 in the following study.
https://researchspace.auckland.ac.nz/bitstream/handle/2292/305/02whole.pdf?sequence=9
Page 32 has nice comments and studies on the motion sensor devices (BodyMedia & FitBit) for free-living calorie estimates.
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.
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Thought for sure there'd be complaints about it, or how do I correct it, or how much is it off. Huh.0
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LOL, give it time....
An interesting read heybales.0 -
• HR monitors are subject to electrical interference (i.e. computers, hairdryers, car engines, etc) which result in either spurious high or low values or momentary loss of data, and the affected data needs to be either removed or replaced by the mean of the surrounding HR values.
If you're drying your hair while exercising, you aren't doing it right0 -
If you're drying your hair while exercising, you aren't doing it right
If cleaning can be classed as exercise, why can't hairdrying? Huh? Huh? 0 -
If you're drying your hair while exercising, you aren't doing it right
If cleaning can be classed as exercise, why can't hairdrying? Huh? Huh?
well, I've read somewhere about a person who was logging brushing her teath as exercise so ... I only consider as exercise the things which are actual sports or workouts specially designed as such.0 -
If you're drying your hair while exercising, you aren't doing it right
If cleaning can be classed as exercise, why can't hairdrying? Huh? Huh?
Yer I dig it. What are we classing it as? Bicep curls, arm raises and tricep extensions with light weights?0 -
How about all of them?If you're drying your hair while exercising, you aren't doing it right
If cleaning can be classed as exercise, why can't hairdrying? Huh? Huh?
Yer I dig it. What are we classing it as? Bicep curls, arm raises and tricep extensions with light weights?
We can always move the hairdryer closer to the scalp for that little extra "burn" :drinker:0 -
This made me laugh way more than it should have... :happy:I've read somewhere about a person who was logging brushing her teath as exercise0 -
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. :-)0 -
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. :-)
Ooh, I'll check it out, thanks!
Yes, HRMs have limitations...but for cardio exercise, it's the BEST option we have. More accurate than any other measure that is accessible to the masses (that I know of anyway).0 -
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. :-)
Gonna have to check this out.
To the OP: great info! <--- serious remark, not snarky.0 -
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!0
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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!
I subtract my BMR from it. My BMR, as tested in a lab, burns about 70 calories per hour. So, I subtract the appropriate amount from what my HRM says. That's usually more than 10% because my workouts are usually 45 min to an hour.0 -
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!
I subtract my BMR from it. My BMR, as tested in a lab, burns about 70 calories per hour. So, I subtract the appropriate amount from what my HRM says. That's usually more than 10% because my workouts are usually 45 min to an hour.
I don't think I understand. You take HRM estimate and substract 70 cals or 75% of 70 cals if you worked out 45 minutes, right?0 -
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!
I subtract my BMR from it. My BMR, as tested in a lab, burns about 70 calories per hour. So, I subtract the appropriate amount from what my HRM says. That's usually more than 10% because my workouts are usually 45 min to an hour.
I don't think I understand. You take HRM estimate and substract 70 cals or 75% of 70 cals if you worked out 45 minutes, right?
Correct. The HRM includes your BMR in it's calorie predictions. So, yesterday I ran for 43 minutes and it said I burned 403 calories. I only recorded 353 calories in MFP. It's a minor thing, but I want to be as accurate as possible since it's all estimated anyway. I didn't used to do this - when I was heavier, it wasn't such a big deal. Then I went to only subtracting if my workout was greater than an hour (which meant only biking). Now I do it all the time. The smaller I get, the more those extra calories count.0 -
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!
I subtract my BMR from it. My BMR, as tested in a lab, burns about 70 calories per hour. So, I subtract the appropriate amount from what my HRM says. That's usually more than 10% because my workouts are usually 45 min to an hour.
I don't think I understand. You take HRM estimate and substract 70 cals or 75% of 70 cals if you worked out 45 minutes, right?
Correct. The HRM includes your BMR in it's calorie predictions. So, yesterday I ran for 43 minutes and it said I burned 403 calories. I only recorded 353 calories in MFP. It's a minor thing, but I want to be as accurate as possible since it's all estimated anyway. I didn't used to do this - when I was heavier, it wasn't such a big deal. Then I went to only subtracting if my workout was greater than an hour (which meant only biking). Now I do it all the time. The smaller I get, the more those extra calories count.0 -
I'm sure it's off by some. That's why I never eat back my exercise calories. I'm too scared of miscalculating what I burn. I mean... I may go over some (into my burned calories), but I never eat them all back (or anywhere close to all).
But, with that said... I still love my heart rate monitor. I like to believe it's closer to accurate than other things could be.0 -
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!
That's a good idea.0 -
Correct. The HRM includes your BMR in it's calorie predictions. So, yesterday I ran for 43 minutes and it said I burned 403 calories. I only recorded 353 calories in MFP. It's a minor thing, but I want to be as accurate as possible since it's all estimated anyway. I didn't used to do this - when I was heavier, it wasn't such a big deal. Then I went to only subtracting if my workout was greater than an hour (which meant only biking). Now I do it all the time. The smaller I get, the more those extra calories count.
Actually, you can expand on that even more.
Now, if you are replacing sleep with exercise, then indeed, take out the calories that would have been burned anyway, to see what extra above and beyond you burned.
So for sleep, that would be BMR.
For sitting on couch watching TV, that would be RMR, slightly higher than BMR.
But get ready for this. When you are doing a calorie logging/deficit routine to lose weight, what you are counting on burning for any hour is actually your daily maintenance figure, pre-deficit.
So if MFP has your daily maintenance set at 2000 before taking the 500 cal deficit, then 2000/24 = 83 calories each hour on avg is expected to be burned.
So you actually subtract that value from your HRM calorie estimate to see what you really burned above and beyond what you were expected to be burning and is already accounted for.0 -
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.0 -
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.0 -
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-zones0 -
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!0 -
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.0 -
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.
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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!0 -
Bump0
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Bump for all those who are trying out their new presents.0
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Very true, might as well take some early workout sessions and figure out how close it is to accurate estimate.0
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save for later0
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