How to test HRM for how accurate calorie burn is

heybales

Well, perhaps you know that HRM estimated calorie burn can be off, especially if you don't have correct stats in it.

It's always claimed it's much more accurate than MFP or other databases, or machine, ect. That claim is usually based on nothing more than observation that it is different than those other sources. If you have made such a claim, think about why you believe that is the case.
It's also always assumed the reading is high if it isn't trusted already, as you can find out below, that is bad assumption too.

Since HRM has definite reason it would have trouble giving decent estimate of calorie burns, or times it should not be used for that purpose anyway, it should be used at correct times if calorie burn is the purpose.
http://www.myfitnesspal.com/topics/show/773451-is-my-hrm-giving-me-incorrect-calorie-burn

How to test how accurate yours is for you?

Well, studies have shown that walking between 2-4 mph level, and basing calculations on formula's, is much more accurate than the 15-25% accuracy a HRM may get if properly set up. And that's 15-25% either direction, not just inflated.

http://www.ncbi.nlm.nih.gov/pubmed/15570150

(4.2 kJ is 1 calorie. Notice the energy expenditure on treadmill and track is almost equal.)

That test Walking was 3.2 mph level for 1 mile for 19 min, calculation was 3.4 calories higher than tested 81 cal, or 4.2% higher.
Running at 6.3 mph level for 1 mile for 9.5 min, calculation was 4.8 calories lower than tested 115 cal, or 4.2% lower.

Why? It literally takes so much energy to move so much mass at so fast a pace for so much time.
Does the amount of energy to lift a 5 lb weight vary if you are male or female, old or young, or is the weight still 5 lbs? :drinker:
It may be easier or harder, but the energy expended is the same. Perhaps a difficult concept to wrap mind around. Now, 5 lb at the end of a short or long arm lifting in front of you, sure, different.

Even adding a bit of incline is more accurate than HRM. Because unless you have far from avg efficiency walking (club foot, fake leg, ect), the calculations are more accurate.

So you can do this before your next regular workout just to know how correct your HRM is.

1 - Confirm your HRM has correct stats. The weight should be your total weight with clothes and shoes you are wearing while exercising. Unless you really are walking naked. Recommend not doing that in the gym.

2 - If treadmill allows weight entry, get it correct too.

3 - 10 min warmup walk, higher HR is better, so probably 4 mph. If HR is not up to at least 120 bpm, then increase incline until it is at 120 and holds steady until the end of the 10 min. Lower speed if you are hitting 120 at 4 mph.

4 - Now start your 20 min test walk, by starting your HRM for actually logging the workout for this next 20 min. Leave the incline where it's at, even if HR starts going up slightly.

5 - At end of 20 min, stop the HRM, note the pace and incline you used, and the weight you were for the test.

6 - Now take your stats to this site, and using the pace and grade, weight on treadmill and your 20 min, use the Gross option (that's what the HRM and treadmill will report, Gross. For purpose of eatback, it would be Net).

http://www.exrx.net/Calculators/WalkRunMETs.html

Now you have the best estimate of calorie burn.

What did your HRM say?

Difference / calculated = % error

The % off will go up as HR goes up.

You can certainly test at another HR to see, but keep it at walking, and lower incline the better accuracy. As soon as you are running, then personal efficiency and method can vary greatly from avg, though it could be much better still if you look at that test data.

So what does the difference in HR mean then? What about 3 months ago when my HR would have been 15 bpm higher perhaps doing this same workout?

A high HR means you needed more oxygen to burn the required fuel, so more carbs being burned, low HR means more fat now.
In addition to this, if you are moving more oxygen with each heart beat compared to 3 months ago because you are more aerobically fit, the HR doesn't have to go as high to provide required oxygen.
That's where the VO2max stat comes into play to help accuracy.

Well, have fun testing.

And if you do have Polar with VO2max self test, at least get the resting HR in the morning and answer the Athlete question correctly.
The correct settings for Athlete and accuracy of their test.
http://www.polar.fi/about_polar/who_we_are/research/fitness_test_with_OwnIndex


Since so many are counting on HRM for "accurate" calorie burns for eating back, or assuming it's always inflated, or have no idea - thought this would be useful self test to show yourself.

Azdak

Unfortunately, I don't have the study at hand, but I did see one that looked at the ACSM running equation and determined that, as speed increased, the equation tended to overpredict energy expenditure. Interestingly, the breakpoint occurred at right about the speed listed in the study you posted--about 6.3 mph (165 m/min). At the endpoint of the study--I think around 8.5 mph--the overestimation was up to 15% (compared to expired gas analysis).

This was for outdoor running--for treadmill running (0% grade), the discrepancy would be a little higher.

But using the treadmill at walking speeds is a decent and easy way to check the HRM. You also need to make sure that the TM is programmed with an accepted equation. This is not a problem with commercial treadmills, but not all home models will follow the same standard.

I would also keep in mind that, even if set up properly, the HRM is also likely to undercount a little because of the time it takes to reach steady state. For the first 3-5 min, your HR will be ramping up, even though you are working at the same workload. The HRM will read the lower number, but the TM will count calories from second 1 of the set workload.

HappilyLifts

I'd like to give this a try, however, I'm pretty sure my HR is around 130bpm as soon as I enter the gym (I've usually been running around doing things indoors immediately beforehand). Sounds like I can still do the test as you say "You can certainly test at another HR to see, but keep it at walking, and lower incline the better accuracy"

One other thing I'm not sure about, that's the term 'grade'. I set the treadmill to a 2% incline, so would I set the 'grade' as 2?

heybales

Unfortunately, I don't have the study at hand, but I did see one that looked at the ACSM running equation and determined that, as speed increased, the equation tended to overpredict energy expenditure. Interestingly, the breakpoint occurred at right about the speed listed in the study you posted--about 6.3 mph (165 m/min). At the endpoint of the study--I think around 8.5 mph--the overestimation was up to 15% (compared to expired gas analysis).

This was for outdoor running--for treadmill running (0% grade), the discrepancy would be a little higher.

But using the treadmill at walking speeds is a decent and easy way to check the HRM. You also need to make sure that the TM is programmed with an accepted equation. This is not a problem with commercial treadmills, but not all home models will follow the same standard.

I would also keep in mind that, even if set up properly, the HRM is also likely to undercount a little because of the time it takes to reach steady state. For the first 3-5 min, your HR will be ramping up, even though you are working at the same workload. The HRM will read the lower number, but the TM will count calories from second 1 of the set workload.

I saw that study too, because I was looking for the incline tests too.

Thanks for catch on not comparing the treadmill calories for that specific test. For one thing, it has extra 10 min on it too.
I corrected the step saying to notice TM calories, just removed that.

heybales

I'd like to give this a try, however, I'm pretty sure my HR is around 130bpm as soon as I enter the gym (I've usually been running around doing things indoors immediately beforehand). Sounds like I can still do the test as you say "You can certainly test at another HR to see, but keep it at walking, and lower incline the better accuracy"

One other thing I'm not sure about, that's the term 'grade'. I set the treadmill to a 2% incline, so would I set the 'grade' as 2?

Good point. Grade and incline are the same.

If a treadmill used Degrees, that would need conversion.

jaxxie

Bump so far love this, thanks Op!

running_shoe

will try this. thanks.

ktrn0312

bump

marekdds

bump for later

yecatsml

looking forward to trying this on the weekend

LovePBandJ

Interesting. Thanks for sharing

HappilyLifts

I'd like to give this a try, however, I'm pretty sure my HR is around 130bpm as soon as I enter the gym (I've usually been running around doing things indoors immediately beforehand). Sounds like I can still do the test as you say "You can certainly test at another HR to see, but keep it at walking, and lower incline the better accuracy"

One other thing I'm not sure about, that's the term 'grade'. I set the treadmill to a 2% incline, so would I set the 'grade' as 2?

Good point. Grade and incline are the same.

If a treadmill used Degrees, that would need conversion.

thanks, can't wait to see what happens.

_Tuyana_

oooh, can't wait to try it tomorrow! See what my Polar FT7 says

MDamoun

Bump

Topsking2010

Bump

LovingCruz

bump

dlegros

I find if I work steady state then my Polar FT7 and the treadmill (Lifefitness) are usually within 4-5 calories of each other.

If I switch to intervals then the FT7 reads significantly higher.

rebasporty

Bump to follow

nacs246

Bump. Try out once I am back to working out. . Thanks for posting!

snowbab

BUMP

heybales

Bump to follow

Ahhhh shooot - why didn't I ask everyone that tested to come back and report their findings.

That would have been super informative.

Because I'm thinking MFP has a bunch of aerobically fit folks that are being underestimated.

MrsR0SE

Interesting......will have a look again on Monday when I go for my run

_Tuyana_

Ahhhh shooot - why didn't I ask everyone that tested to come back and report their findings.

That would have been super informative.

Because I'm thinking MFP has a bunch of aerobically fit folks that are being underestimated.

Just got back from the gym, I tried your suggestion while warming up. My heart rate stayed somewhere around 120bpm (+/-5). The funny thing is, that website gave me exactly the same calories as the treadmill (98 cal), while my Polar FT7 had it at 105 cal. I was at 6 km/hr pace and incline=3

elizabethis

bump

rmarley05

I will have to try this, my HRM is always under the treadmill and MFP estimates. I always change the number when I enter in my exercises because they aren't usually close at all! Thanks for sharing.

Lisaherbalmomma

Bump

Lrdoflamancha

Bump

chrissilini

bump

knwitall

Bump for later! Too early to think that hard!

valmb2

bump to read later

heybales

Well, got to do my test with my freshly tweaked Garmin 310XT, supposedly so it's using my test VO2max, and it has my tested HRmax too. Height had to be set to 90 and age to 20 (I'm 70" and 44).

5 minutes really wasn't enough of a warmup, or still tired from 10 mile run yesterday, but oh well.

10 min, 4 mph, 6% incline.
HR started at 120 and avg 124 for the whole time.

Garmin reported 79.
Calculator is 111.

So over an hr, that's under-reported by 192 calories, at not that significant of a HR. That's the bottom of my Active Recovery HR zone, as low as the zones go.

Easily see 250-400 depending on the HR. 5 hrs a week, and that's 1250-2000 shortage.

That is a bad under-estimate for trying to eat for performance and get the most out of my workouts. And I thought for sure I was coming in on the high end so as not to do that.

Any other reports?

This might be worth trying some steeper incline walk tests with better warmup, and reach a HR steady at the top of each of my HR zones, that can be done walking anyway. Then that'll let me confirm what the HRM is telling me.