Polar HRM calorie burn estimate accuracy - study
Replies
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Looking at the abstract, it says it was OVERestimating for women, so it's doubly bad.
"In females, the PHRM significantly overestimated mean EE on the treadmill (by 2.4 kcal·min-1), cycle (by 2.9 kcal·min-1), and rower (by 1.9 kcal·min-1) (all P < 0.05). "
Also, even if you enter VO2 max estimates, it still was found to overestimate for women by 12%.
"Conclusion: When the predicted values of V̇O2max and HRmax are used, the Polar S410 HRM provides a rough estimate of EE during running, rowing, and cycling. Using the actual values for V̇O2max and HRmax reduced the individual error scores for both genders, but in females the mean EE was still overestimated by 12%."0 -
This makes me feel better for buying a cheap HRM. It was inaccurate, too, but at least I didn't pay much for it!
Meh, could make scrupulously eating all those exercise calories back a chancy proposition for women!0 -
My head hurts!
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Now this has got me thinking...I have a tunturi C85 elliptical which comes with a heart rate strap. I was thinking that the calorie burn was low for the effort i was putting in so i put on my fitbit and my polar ft7.
The fitbit gave me slightly under double the burn of the tunturi strap, while the HRM gave me approx 38% more than the Tunturi.
Question is now...Which do i actually trust when i`m eating back cals?????
Most exercise machines merely display the HR for your use, or at most can base a program off of it. But they don't use it in calorie burn calcs.
If you don't wear it, does the burn seem to be the same if you keep the same cadence, pace, tension, ect?
The Fitbit has no idea of your level of effort, merely estimating you walked this much and knowing you weigh this much, therefore it took this much energy to move this much mass this fast this long. And that actually has a great deal of accuracy to it - if it really knows how far you walked and what kind of incline. But elliptical?
And usually only valid for walking level exercise. If the stride length is corrected, can be good for jogging too.
HRM would be more accurate than either, and could be made even more so with the correction to biggest thing, HRmax stat. It calculates it based on 220-age, which may have little bearing on reality.
If that is you in picture, being a guy, as the study shows, you have better chance of lucking out and it being close to correct.
You can self-test too.
http://www.myfitnesspal.com/topics/show/466973-i-want-to-test-for-my-max-heart-rate-vo2-max
If i don`t wear it its difficult to say, as i have to grab the handles instead therefore lessening my calorie burn as my arms aren`t moving.....But thanks for the reply, i`ll just stick to the Polar for my cals burnt..0 -
Bottom line: If you're female and 'eating back' based on your Polar, you probably should cut its estimate in half (33% for the overestimate and some for double counting your BMR). So if it says you burned 500 in Zumba, maybe eat back 250 to really reflect your incremental calorie burn from the workout.0
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I find this very very interesting as my heart rate is generally very very low - resting or otherwise (high fitness level and low blood pressure) - sometimes it takes my HRM even a while to read my heart rate - i get very very low burns even for huge, intesnse workouts - i've often wondered whether it reads incorrectly.... webistes that you can plug the numbers into suggest my numbers shouild be higher....
would that make sense?
Since it appears you are ready to have fun with numbers, that Polar study and formula is more accurate if you know your VO2max, which likely your HRM doesn't have either, because indeed, you may be very cardio fit and very efficient.
Now, if your HRM has trouble reading the HR, that makes me wonder if it's missing enough beats to throw it off. That's not good either. Ever tried moving the strap to the left or right, as opposed to centered on your body?
Of course if low HR, low calorie burn. But also hard to do HR zone training if not accurate.
Now, it may be that 220-age is too high a HRmax for you, and yours is actually lower, and even with lower HR you actually burn more.
Anyway, as to having more fun with numbers, use this spreadsheet, HRM tab, upper section has instructions on getting pretty good estimated VO2max figure based on bodyfat%.
Plug that into the calorie burn site with other stats and see how much difference. May not be much, may be much.
This topic describes the tabs and the link for spreadsheet.
http://www.myfitnesspal.com/topics/show/677905-spreadsheet-for-bmr-tdee-deficit-calc-macro-calc-hrm0 -
This makes me feel better for buying a cheap HRM. It was inaccurate, too, but at least I didn't pay much for it!
Meh, could make scrupulously eating all those exercise calories back a chancy proposition for women!
Very true, check out the post above this one on calculating your VO2max, and using a website with your HRM.
If you are given at least an avgHR for the workout - you can still get good estimate.0 -
Standard deviation of 13% as well, so a 'normal' woman could have calorie burn overestimated by up to 38%, and that is with vo2 max calibrated. Uncalibrated the standard error is up to a 75% overestimation for women.Looking at the abstract, it says it was OVERestimating for women, so it's doubly bad.
"In females, the PHRM significantly overestimated mean EE on the treadmill (by 2.4 kcal·min-1), cycle (by 2.9 kcal·min-1), and rower (by 1.9 kcal·min-1) (all P < 0.05). "
Also, even if you enter VO2 max estimates, it still was found to overestimate for women by 12%.
"Conclusion: When the predicted values of V̇O2max and HRmax are used, the Polar S410 HRM provides a rough estimate of EE during running, rowing, and cycling. Using the actual values for V̇O2max and HRmax reduced the individual error scores for both genders, but in females the mean EE was still overestimated by 12%."
Honestly, this is unsurprising, as there are a lot of factors beyond heart rate that influence calorie burn.
This is why I prefer using an activity multiplier and not eating back calories for weight loss. The margin for error both in estimating dietary intake (which is every bit as inaccurate as this for most people), and estimating exercise expenditures, when combined make it very difficult to accurately estimate net caloric intake.
Just my 2c.0 -
This is why I prefer using an activity multiplier and not eating back calories for weight loss. The margin for error both in estimating dietary intake (which is every bit as inaccurate as this for most people), and estimating exercise expenditures, when combined make it very difficult to accurately estimate net caloric intake.
Just my 2c.
Very true. And at least with the activity levels, those are generally very underestimated calorie burn levels except for walking.
So once you see steady weight loss, you can see what your deficit must be for that to happen, and therefore what your true TDEE must be. That is very useful info.
Of course, that doesn't take into account losing fat and increasing LBM, so scale may not move much, but body is. Well, at least gives good view of what's going on.
Then use the HRM for what it was originally designed for - making smart workouts for performance improvements.0 -
Wonder why they took the study down0 -
Personally I don't care if mine is off, just having one in itself, seeing the results makes me WANT to workout more. It makes me want to get more exercise in to see the numbers go up. Ever since I got it I've been in love with it :P Interesting study I guess, mine's an FT60 so I would assume it's a least a little more accurate either way I'm happy, was $130 or whatever it cost well spent imo
this. getting an hrm bumped up my physical activity..0 -
I have a polar FT4. Been using it for about a year and have had wonderful results. Hate it when people want to put doubt in people's minds.0
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So in layman's terms, my FT7 is giving me the wrong results in terms of calories burnt?
That's disappointing.
How accurate is your calories you're supposed to consume?? That's probably inaccurate too. Everything comes with inaccuracies. So don't worry about it.
This.
Just because something is supposed to have x calories, there is quite a variety - a 100 calorie snack pack means it has APPROXIMATELY 100 calories.
This is why I don't usually eat back exercise calories. On long bike ride days when I burn 1,500+ I will eat a little more, but you just never know.
This is also why I went past the FT4 and the FT7 and got the FT40 with VO2Max test - not that it's 100% accurate, but it's a little closer. And honestly, I totally agreed with the max heart rate on the test originally - I would reach that point and I would feel like my head was going to explode. The fun part is that now I hit that point a lot. I need to redo my VO2Max test. :happy: (Which essentially is one of the reasons I wanted the HRM - to see myself improving!)0 -
Just in my experience, my heart rate monitor gives MUCH higher readings that my BodyMedia. I have both a Polar FT4 and a BodyMedia Fit. I use the HRM very infrequently - I don't trust it at all.
For example, we went on a tough hike last Thursday. Just for kicks, I wore both my BodyMedia and my Polar FT4. The Polar said I burned 1829 calories and the BodyMedia said I burned 889.
Here are a few other examples of the discrepancy between the two devices:
65 minutes of circuit training
Body Media Fit: 284 calories
Polar FT4 Heart Rate Monitor: 537 calories
65 minutes of circuit training
Body Media Fit: 284 calories
Polar FT4 Heart Rate Monitor: 537 calories
35 minutes of step aerobics and 30 minutes hiking
Body Media Fit: 439 calories
Polar FT4 Heart Rate Monitor: 738 calories
60 minutes of cardio drills
Body Media Fit: 361 calories
Polar FT4 Heart Rate Monitor: 627 calories
I stopped using my HRM regularly a couple months ago and have been using the BodyMedia to determine my TDEE. It's been very effective. I finally feel like I'm not struggling to accurately figure my maintenance calories.
Using the BodyMedia, I've stayed a 137 pounds (female, 5'9", 20%bf) for six weeks now - which is exactly where I want to be!0 -
I have a Polar FT4 and eat back my exercise calories and have had no problem losing weight.Bottom line: If you're female and 'eating back' based on your Polar, you probably should cut its estimate in half (33% for the overestimate and some for double counting your BMR). So if it says you burned 500 in Zumba, maybe eat back 250 to really reflect your incremental calorie burn from the workout.0 -
I have a polar FT4. Been using it for about a year and have had wonderful results. Hate it when people want to put doubt in people's minds.
It's not doubts, it's about how to make it more accurate.
I love how someone that has never had a HRM before will comment "I love mine, very accurate" - based on what exactly?
How in the world would someone know it's accurate?
Because it's different or lower value than MFP?
Wow.
Not denying that some level of users will have as decent accuracy as possible. But they would never know that.
But for women, the majority have a better chance NOT being within HRmax of 220-age by 10 bpm, women are all over the board.
Hence the benefit of testing for real HRmax, getting stat correct on HRM, and getting better calorie estimate - if purpose is to maximize weight loss, but keep a safe deficit.0 -
Just in my experience, my heart rate monitor gives MUCH higher readings that my BodyMedia. I have both a Polar FT4 and a BodyMedia Fit. I use the HRM very infrequently - I don't trust it at all.
For example, we went on a tough hike last Thursday. Just for kicks, I wore both my BodyMedia and my Polar FT4. The Polar said I burned 1829 calories and the BodyMedia said I burned 889.
Here are a few other examples of the discrepancy between the two devices:
65 minutes of circuit training
Body Media Fit: 284 calories
Polar FT4 Heart Rate Monitor: 537 calories
65 minutes of circuit training
Body Media Fit: 284 calories
Polar FT4 Heart Rate Monitor: 537 calories
35 minutes of step aerobics and 30 minutes hiking
Body Media Fit: 439 calories
Polar FT4 Heart Rate Monitor: 738 calories
60 minutes of cardio drills
Body Media Fit: 361 calories
Polar FT4 Heart Rate Monitor: 627 calories
I stopped using my HRM regularly a couple months ago and have been using the BodyMedia to determine my TDEE. It's been very effective. I finally feel like I'm not struggling to accurately figure my maintenance calories.
Using the BodyMedia, I've stayed a 137 pounds (female, 5'9", 20%bf) for six weeks now - which is exactly where I want to be!
Ya, if you think the HRM has chance of inaccuracy, that BMF really does for any exercise related. Just because it's higher doesn't mean that is the one that is inaccurate, not sure the logic on that.
Even the study quoted above recognized the fact the BMF and others like it are fine for daily non-exercise activity, but not decent exercise.
Your HRM is much more correct than BMF on every single one of those things.
http://www.ncbi.nlm.nih.gov/pubmed/15126727
Sensewear makes the BodyMedia and Bodybugg units. Study pointed out when Sensewear provided specific algorithms to be used on the different exercises, much better estimate.
But do you get to tell the BMF site what your exercise was? No, they still use the general formula's.
the SenseWear Pro Armband significantly underestimated total energy expenditure by 14.9 +/- 17.5 kcal (6.9 +/- 8.5%) during walking exercise, 32.4 +/- 18.8 kcal (28.9 +/- 13.5%) during cycle ergometry, 28.2 +/- 20.3 kcal (17.7 +/- 11.8%) during stepping exercise, and overestimated total energy expenditure by 21.7 +/- 8.7 kcal (29.3 +/- 13.8%) during arm ergometer exercise (P < or = 0.001).0 -
I have a polar FT4. Been using it for about a year and have had wonderful results. Hate it when people want to put doubt in people's minds.
Yeah, God damn those that throw around facts and research papers done at universities specifically on polar watches that contain math that proves they are inaccurate for women and list it right down to the standard deviations and educating the public. I read the study. It's fact, they published it was inaccurate.0 -
Just in my experience, my heart rate monitor gives MUCH higher readings that my BodyMedia. I have both a Polar FT4 and a BodyMedia Fit. I use the HRM very infrequently - I don't trust it at all.
For example, we went on a tough hike last Thursday. Just for kicks, I wore both my BodyMedia and my Polar FT4. The Polar said I burned 1829 calories and the BodyMedia said I burned 889.
Here are a few other examples of the discrepancy between the two devices:
65 minutes of circuit training
Body Media Fit: 284 calories
Polar FT4 Heart Rate Monitor: 537 calories
65 minutes of circuit training
Body Media Fit: 284 calories
Polar FT4 Heart Rate Monitor: 537 calories
35 minutes of step aerobics and 30 minutes hiking
Body Media Fit: 439 calories
Polar FT4 Heart Rate Monitor: 738 calories
60 minutes of cardio drills
Body Media Fit: 361 calories
Polar FT4 Heart Rate Monitor: 627 calories
I stopped using my HRM regularly a couple months ago and have been using the BodyMedia to determine my TDEE. It's been very effective. I finally feel like I'm not struggling to accurately figure my maintenance calories.
Using the BodyMedia, I've stayed a 137 pounds (female, 5'9", 20%bf) for six weeks now - which is exactly where I want to be!
Ya, if you think the HRM has chance of inaccuracy, that BMF really does for any exercise related. Just because it's higher doesn't mean that is the one that is inaccurate, not sure the logic on that.
Even the study quoted above recognized the fact the BMF and others like it are fine for daily non-exercise activity, but not decent exercise.
Your HRM is much more correct than BMF on every single one of those things.
http://www.ncbi.nlm.nih.gov/pubmed/15126727
Sensewear makes the BodyMedia and Bodybugg units. Study pointed out when Sensewear provided specific algorithms to be used on the different exercises, much better estimate.
But do you get to tell the BMF site what your exercise was? No, they still use the general formula's.
the SenseWear Pro Armband significantly underestimated total energy expenditure by 14.9 +/- 17.5 kcal (6.9 +/- 8.5%) during walking exercise, 32.4 +/- 18.8 kcal (28.9 +/- 13.5%) during cycle ergometry, 28.2 +/- 20.3 kcal (17.7 +/- 11.8%) during stepping exercise, and overestimated total energy expenditure by 21.7 +/- 8.7 kcal (29.3 +/- 13.8%) during arm ergometer exercise (P < or = 0.001).
Meh
My weight is finally stable/predictable with the BodyMedia numbers. So, whatever... it seems to work for me.0 -
So in layman's terms, my FT7 is giving me the wrong results in terms of calories burnt?
That's disappointing.
That would be saying too much. It would be more accurate to say it quite likely may be doing so, but the variation could be above or below the actual calories burned.0 -
Why do women always get the short end of the stick???????
Oh, well, whatever I am doing is working, so I will continue to do it
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Because they keep dating men who are not well endowed :laugh:Why do women always get the short end of the stick???????
Oh, well, whatever I am doing is working, so I will continue to do it0 -
This is also why I went past the FT4 and the FT7 and got the FT40 with VO2Max test - not that it's 100% accurate, but it's a little closer. And honestly, I totally agreed with the max heart rate on the test originally - I would reach that point and I would feel like my head was going to explode. The fun part is that now I hit that point a lot. I need to redo my VO2Max test. :happy: (Which essentially is one of the reasons I wanted the HRM - to see myself improving!)
If you want to see how Polar is doing that test without really giving you a VO2max test, they are basing it on a study, and tweaking it.
But they are using BMI in formula, not the more accurate bodyfat% the study found.
Here is the study and method of calculating your own VO2max to decent accuracy, probably more than HRM.
http://www.myfitnesspal.com/topics/show/577839-hrm-s-with-vo2max-stat-improve-calorie-estimate
And here is spreadsheet in this topic that has HRM tab at bottom that has it easier to do. Might see how it compares to what the HRM figured out.
Because your true HRmax doesn't change with exercise, except for the time of doing none to doing some, but you can't train it higher. VO2max is mostly genetics too, and not that much movement, though some possible if specific training.
http://www.myfitnesspal.com/topics/show/677905-spreadsheet-for-bmr-tdee-deficit-calc-macro-calc-hrm0 -
So in layman's terms, my FT7 is giving me the wrong results in terms of calories burnt?
That's disappointing.
So FT7 my wife & I bought are crap.... DAMN!! I'M SUEING THE *kitten* FOR LYING AND RIPPING EVERYBODY OFF!!!!!0 -
I have a polar FT4. Been using it for about a year and have had wonderful results. Hate it when people want to put doubt in people's minds.
It's not doubts, it's about how to make it more accurate.
I love how someone that has never had a HRM before will comment "I love mine, very accurate" - based on what exactly?
How in the world would someone know it's accurate?
Because it's different or lower value than MFP?
Wow.
Not denying that some level of users will have as decent accuracy as possible. But they would never know that.
But for women, the majority have a better chance NOT being within HRmax of 220-age by 10 bpm, women are all over the board.
Hence the benefit of testing for real HRmax, getting stat correct on HRM, and getting better calorie estimate - if purpose is to maximize weight loss, but keep a safe deficit.
I am always amazed at how people will dismiss exercise machine calorie numbers out of hand but will accept HRM calorie numbers as "truth" without any question whatsoever.
Whoever designed human brains had a wicked sense of humor.
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I am starting to feel a little stupid. I used your spread sheet to compare the VO2 max thing because I have a polar.
I got 22.11 for the BMI VO2 max and 21.65 for the BF one. I put it in the website you had a link for in there and there was only a difference of like 2 calories burned. I hope I did this right.....
On a side note, if my polar is overestimating my calorie burn, it tends to lose my heart rate when I am on the floor doing crunches (it just drops a lot, into the 120s or 110s), which would drop my average heart rate a little bit, so I guess in a way that would somewhat compensate for the overestimation.....
*brain asplodes!*0 -
I am always amazed at how people will dismiss exercise machine calorie numbers out of hand but will accept HRM calorie numbers as "truth" without any question whatsoever.
Whoever designed human brains had a wicked sense of humor.
Do you think the machine values are perhaps way off because the calibration of actual speed is bad?
I was on a treadmill at gym that was flashing a warning about lubricating the belt or such, so I told the staff.
"we'll reset the warning"
Not we'll fix it, not they need oil from time to time, ect. We'll get rid of the warning.
Made me wonder if they ever did the required re-calc after so many belt miles. I got the manual for it awhile back to use the trainer's features on it (nothing like saving your interval routine under a trainer's code for access later, if I get that machine anyway!) and noticed re-calc is supposed to be part of normal routine on it.
If belt is off, then speed is off, then calc's is off. Because I just don't see why they wouldn't use the standard calc's for MET's when they know the weight, pace, incline, ect and could nail the calories needed for that effort.0 -
I am starting to feel a little stupid. I used your spread sheet to compare the VO2 max thing because I have a polar.
I got 22.11 for the BMI VO2 max and 21.65 for the BF one. I put it in the website you had a link for in there and there was only a difference of like 2 calories burned. I hope I did this right.....
On a side note, if my polar is overestimating my calorie burn, it tends to lose my heart rate when I am on the floor doing crunches (it just drops a lot, into the 120s or 110s), which would drop my average heart rate a little bit, so I guess in a way that would somewhat compensate for the overestimation.....
You got it exactly. It just means your bodyfat% is probably close to expected for your BMI.
So the formula's end up with close enough result.
But for someone very muscular, whose BMI is high but in excellent health and low bodyfat% - they would have a big difference of perhaps 9 VO2.
Which would still only lead to a difference of 60 calories per hr more. But over the course of a week say 6 hrs of exercise, that's 360 calories, over 1/4 lb difference in potential weight loss.
I guess I should add a section to spreadsheet on getting HR zone training based on VO2max figure, it is a valid training method too.
Think that would be useful?0 -
As always, great post (and subsequent responses) Heybales. I love when people show up to the party with real information!
And to those whose HRM numbers are producing the results you want- then stick with it! You may well fall within the population of people for whom the algorithm works. Check back on this thread if and when you hit a plateau. You don't have to take the information presented as a personal affront. It's not- it's just information- the more the better.1 -
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