Polar HRM calorie burn estimate accuracy - study

mbk830

bump

jdavis193

Whether it is off or not, I don't know. But I use a Polar FT60 and the Body Media FIT and have to say that both are very close to each other after nearly every workout I've done - whether that is walking, treadmill, elliptical, spinning.

I have this one to and I love it!

TrishasTime

bump

freya33

I have a polar F11 and a garmin, the garmin gives about half the calorie burnt on the polar. I just use polar in the gym and garmin outside and at the end ot the day it is the weight lost that counts and I just use the HRM to push me to work harder.

ALH1981

Sois the inaccuracy in additional burn calculations or reduced burn calculations?????

Regardelss, as long are you are benchmarking constantly to the same scale does it matter??? The issue would be if you used varied scales and compared them...

jonski1968

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?????

heybales

I have a polar F11 and a garmin, the garmin gives about half the calorie burnt on the polar. I just use polar in the gym and garmin outside and at the end ot the day it is the weight lost that counts and I just use the HRM to push me to work harder.

If the Garmin is newer and uses Firstbeat algorithms for calorie burn estimates (you may have given an athletic level in stats) it is more accurate.

Then again, they both may have guesstimated different HRmax stat, and if that is different it will calc very different.

Do remember to, pushing it as hard as you can each time is not always the best workout, especially if over 30 min each day.
Your body never gets a good chance to recover and rebuild stronger.
So while you are pushing the HR just as high, the body isn't getting as strong as it could if given good rest and recovery.

heybales

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

heybales

Sois the inaccuracy in additional burn calculations or reduced burn calculations?????

Regardelss, as long are you are benchmarking constantly to the same scale does it matter??? The issue would be if you used varied scales and compared them...

The variance was both directions, possibly massive (30%), for women.

It would matter if you are using the calorie burn estimate to eat back your exercise calories correctly to feed your workout. But how much to feed if potentially way off.
One direction could mean you are constantly creating a bigger than healthy loss deficit and perhaps slowing down metabolism, the other direction means you aren't getting the deficit you could be getting that is healthy level.

At least with one direction, your body is getting fed to make great changes because of the exercise. The other direction, not so much to possibly not at all well.

If you are benchmarking to compare performance, than pure HR should be used, not calorie burn, as a means of knowing if it was a good workout.
And at that point, the HRmax and zones comes into play for better workout strategy, but as study showed, the HRmax 220-age was off for women.

ALH1981

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?

mcarter99

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%."

MaraDiaz

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!

jillica

My head hurts!

jonski1968

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..

mcarter99

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.

heybales

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-hrm

heybales

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.

wackyfunster

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%."

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.

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.

heybales

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.

CoderGal

Guys, we got it lucky.

http://www.ux1.eiu.edu/~cfje/5700/PolarWatch-study-MSSE.pdf

Wonder why they took the study down