Is my HRM giving me incorrect calorie burn?

heybales

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.

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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.

heybales

Thought for sure there'd be complaints about it, or how do I correct it, or how much is it off. Huh.

HappilyLifts

LOL, give it time....
An interesting read heybales.

elizak87

• 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 right

Murf1968

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?

head_in_rainbows

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.

elizak87

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?

Murf1968

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?

How about all of them?

We can always move the hairdryer closer to the scalp for that little extra "burn" :drinker:

Murf1968

I've read somewhere about a person who was logging brushing her teath as exercise

This made me laugh way more than it should have... :happy:

jasonheyd

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. :-)

omma_to_3

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).

JustJennie1

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.

sevsmom

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!

omma_to_3

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.

head_in_rainbows

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?

omma_to_3

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.

omma_to_3

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.

AmberJo1984

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.

AmberJo1984

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.

heybales

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.

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.