WARNING! POLAR HEART RATE MONITORS DEFECTIVE!

Hannah645

I do enjoy looking at numbers and analyzing everything. At some point though, I think you have to assume that losing weight is a lot more estimating than we wish it was. There are many articles floating around the internet over nutrition labels as well as heart rate monitors. I've read that even groceries can be within 7 percent off its listed calories and restaurant meals within 20 percent. So even with a scale, you're not always eating exactly the number of calories you think.

I'm 23 and my heart rate hovers near 180 during runs. If I run for 30 minutes, I make sure to eat a couple hundred extra calories that day. I don't wear my garmin hrm during every run because I don't think it's capable of telling me anything super significant. I can tell when I'm pushing myself.

From your posts it seems that you are a very numbers oriented, exact kind of person. I hope you can get some answers from Polar because there does seem to be a discrepancy at heavier weights.

heybales

I think most people trying to lose weight the calories burned is the most important stat for them.

Just looking at the raw data though you must see something is amiss. Without changing any other variables when you increase the weight the calories burned goes down. It simply does not make sense.

Well, then there is the misunderstanding and problem.

You have a tool that has been shown to loosely tie together HR and calories burned, by formula based on other stats actually.

But it is a loose affiliation even with the same person.

But you are using a tool missing some pieces, so it's not as good.

Could Polar have just included the fields for stats in the cheaper watches - sure. The formula is already there.

You can decide how much you like or dislike Polar's business practices.

I don't like them, to have such minor contrived differences between models seems stupid to me.

Like HR zone alarms. Put an upper alarm on the FT7, but not a lower one.
They had models in the past where cheaper had upper but no audio option, so you had to look at watch to see icon. Stupid. Watch already beeped for things.

It takes more effort to go back in and disable some functions for the cheaper versions. But from signs on MFP and elsewhere, their marketing methods work just fine.
And they are catering to the crowd that wants calorie burn info.

Later when they discover they want more than no or few features, they'll spend big bucks on more expensive model to actually train with.

peterdt

Thank you all for your input and observations.

After all the input I've heard so far the conclusion is still the same

The higher the weight you enter on the Polar FT7 the more likely that it is not accurate.

For example, at 300 pounds or above it appears to be between 30-50%. Surely it must vary 0-20% from reality depending on a lot of factors from individual to individual but the numbers I'm getting a just way off. This is also true for a lot of other people posting here, especially at higher weights. Something is surely amiss.

heybales

Thank you all for your input and observations.

After all the input I've heard so far the conclusion is still the same

The higher the weight you enter on the Polar FT7 the more likely that it is not accurate.

For example, at 300 pounds or above it appears to be between 30-50%. Surely it must vary 0-20% from reality depending on a lot of factors from individual to individual but the numbers I'm getting a just way off. This is also true for a lot of other people posting here, especially at higher weights. Something is surely amiss.

I'll agree that at some point, the BMI method of assuming VO2max probably is just a matter of "greater than this, then that" type table.
A sliding scale would be best, but even then, probably only up to a certain level, then everything past that the same number is used for.

Good to know though, I've been trying to figure out how to backward engineer how they do the BMI estimate method, as many studies do use it.

But also, past a certain weight you don't continue a linear progressive increase in calories burned.

Notice these very accurate walking calc's up to 4mph. More accurate than HRM's in fact by a big margin. Not linear if graphed out.

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

EvgeniZyntx

I'm not sure if you got the correct answer in all these pages, because probably only half-dozen that I've seen on MFP has the answers.

That cheaper Polar model has NO stat for VO2max, which is then required to estimate.

Because calories burned is totally related to that stat and HRmax.

So how do you estimate VO2max with no stat?

BMI - Polar assumes that if you weigh more and your BMI is worse, you are less in shape, therefore an elevated HR means you burned say 500 calories to accomplish a given workload for your weight.

But, if you are actually in shape at that weight, your lower HR to accomplish the same work still means you burned 500 calories, but Polar sees the lower HR and assumes being unfit, you didn't work as hard, so they show you only burned 400 calories.

Same thing works if you kept the HR exactly the same, but your weight went down.

Heavy weight, HR of 150, burned 500.
Lower weight, HR of 150, burned 600.

It's not a defect - except for people expecting a HRM with missing stats to give a great estimate of calories burned what that isn't even the tool's primary purpose.

This is why those cheaper models really under-report calories burned as you get fit but don't lose weight as fast.

If you did a treadmill walk at 4 mph at given weight and 1 week into working out, your HR may have been 150.
You kept doing it, you got fit.
You do the same walk at the same weight. Did the workload change? The calories burned is the same. But now your HR only needs to be 120 to do the same amount of work.

Calories burned is the same.

But for the Polar with no VO2max stat, the first walk at 150 gets bigger calorie burn reported than the second walk at 120 - even though the calories burned would be exactly the same!

Which is right? Probably inbetween. That BMI method assumes an average fitness level for given BMI.

Try experimenting - change the height now by about 20 inches and see what happens. Make it taller for given weight so BMI is in healthy zone.

The input that you give here is very good in terms of the issue at hand but I'm going to suggest an issue with your example but not your analysis. Let's talk about the treadmill example, if you don't mind.

In short, while the mechanical work is the same and the load did not change the muscular efficiency does change (fiber recruitment, neurological changes, mitochondrial whatnot, and even muscle fiber type over long term) and muscular work has a large thermal component that is not the same in the two cases. From my human physiology courses (in the last century) mechanical work only corresponds to about a quarter of metabolic energy use; it's the other components of energy use that are also changing. Therefore the metabolic calories consumed are not the same in this example for the fit and not fit. While VO2max does increase with training and probably remains the best measure there are significant efficiency gains that do not translate to VO2max gains.
Examples of this are all the elite cycling studies where VO2max goes slightly down with increased work/power capacity.
And of course, that woud be another example of issues with HRM used to calculate "burn".

And there is the whole confusion between relative and absolute V02max. As you likely know, two individuals with the same absolute V02max will have different fitness levels depending on their weight.

But I think you hit the head on the head - the use of a BMI in these HRM makes assumptions about fitness levels that can be significant error inducing. Probably for the general population, even at higher weight the error level is not that high as the discussion here has led us to believe. I.e. if I was keeping a specific HR and weighed 3x I'd certainly go slower, cover less distance and provide less mechanical work.

Anyway, my conclusion is that I should get my old Polar repaired or get another one :huh: - and that I do tend to focus on the right fitness parameters with regards to a HRM - resting HR (used as an estimator of VO2max), max HR for a given effort, and time to return to a base HR after effort. As an old cyclist, those were our canonic training guides and I sort of only glance at them now.

Thanks for the discussion points.

cchambliss

Was considering purchasing the FT4. This one should be accurate I hope?

heybales

Was considering purchasing the FT4. This one should be accurate I hope?

More than a cheaper one. Is up to 40% still accurate enough for you?
http://www.myfitnesspal.com/topics/show/459580-polar-hrm-calorie-burn-estimate-accuracy-study

But as expressed above, all kinds of reasons for inaccuracies even without the fact the cheaper Polar like the FT4 is missing a very important stat they will be assuming, based on your BMI.

heybales

In short, while the mechanical work is the same and the load did not change the muscular efficiency does change (fiber recruitment, neurological changes, mitochondrial whatnot, and even muscle fiber type over long term) and muscular work has a large thermal component that is not the same in the two cases. From my human physiology courses (in the last century) mechanical work only corresponds to about a quarter of metabolic energy use; it's the other components of energy use that are also changing. Therefore the metabolic calories consumed are not the same in this example for the fit and not fit. While VO2max does increase with training and probably remains the best measure there are significant efficiency gains that do not translate to VO2max gains.
Examples of this are all the elite cycling studies where VO2max goes slightly down with increased work/power capacity.
And of course, that woud be another example of issues with HRM used to calculate "burn".

And there is the whole confusion between relative and absolute V02max. As you likely know, two individuals with the same absolute V02max will have different fitness levels depending on their weight.

Ya, I love that running pace estimates that take your VO2max and calculate a pace you should be able to do. Without weight being asked for. Ya, I'll run my knees and feet into the ground maintaining that 7 min pace for oh, 3-4 miles right now.

I'm thinking running might see better efficiency gains.
I used the walking example because of the tight bell curve on energy spent walking different speeds. I don't think you'd see significant efficiency gains if you'd done any walking. Just not used to doing it for a long time.
But really, some of what you describe as changing and improving efficiency, is exactly why the VO2max improves, and HR lowers, to provide the same oxygen to a system that is much more efficient at using it now. So the energy use is a whole lot tighter I'd believe unless you are comparing different people, or really improving your running, biking, swimming efficiency.

Like the study of cyclist and optimum cadence. Rider naturally selected wasn't the most efficient, but it gave better results over all. Pro-cyclist, so they knew what felt like their own best efficiency.

Oh, the study showing how tight the calorie burns are for walking.

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

While it was mainly talking about the calculation predictions, the measured expenditure is within 5 calories when weight adjusted. We seem to walk at certain speeds with pretty equal efficiency since we've been doing it for so long. Once we can pull ourselves off the bike anyway.

SToast

I've had no problems with my FT4. It gives EXACTLY the same reading as the cardio equipment at my gym after I punch in my details It gave me about a 5000 odd calorie reading for my last marathon and my g'friend who is same age, similar build to me clocked similar results on her FT4 over a same distance. Check your battery, check that you have the strap on properly and the sensors are wet. Remember to adjust your weight in the settings as it changes too. Hope you find a better result.

This. I've only had mine for about a week but so far it's been right on gym equipment and other calorie calculators.

EvgeniZyntx

In short, while the mechanical work is the same and the load did not change the muscular efficiency does change (fiber recruitment, neurological changes, mitochondrial whatnot, and even muscle fiber type over long term) and muscular work has a large thermal component that is not the same in the two cases. From my human physiology courses (in the last century) mechanical work only corresponds to about a quarter of metabolic energy use; it's the other components of energy use that are also changing. Therefore the metabolic calories consumed are not the same in this example for the fit and not fit. While VO2max does increase with training and probably remains the best measure there are significant efficiency gains that do not translate to VO2max gains.
Examples of this are all the elite cycling studies where VO2max goes slightly down with increased work/power capacity.
And of course, that woud be another example of issues with HRM used to calculate "burn".

And there is the whole confusion between relative and absolute V02max. As you likely know, two individuals with the same absolute V02max will have different fitness levels depending on their weight.

Ya, I love that running pace estimates that take your VO2max and calculate a pace you should be able to do. Without weight being asked for. Ya, I'll run my knees and feet into the ground maintaining that 7 min pace for oh, 3-4 miles right now.

I'm thinking running might see better efficiency gains.
I used the walking example because of the tight bell curve on energy spent walking different speeds. I don't think you'd see significant efficiency gains if you'd done any walking. Just not used to doing it for a long time.
But really, some of what you describe as changing and improving efficiency, is exactly why the VO2max improves, and HR lowers, to provide the same oxygen to a system that is much more efficient at using it now. So the energy use is a whole lot tighter I'd believe unless you are comparing different people, or really improving your running, biking, swimming efficiency.

Like the study of cyclist and optimum cadence. Rider naturally selected wasn't the most efficient, but it gave better results over all. Pro-cyclist, so they knew what felt like their own best efficiency.

Oh, the study showing how tight the calorie burns are for walking.

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

While it was mainly talking about the calculation predictions, the measured expenditure is within 5 calories when weight adjusted. We seem to walk at certain speeds with pretty equal efficiency since we've been doing it for so long. Once we can pull ourselves off the bike anyway.

Ok, for walking, I'd completely agree, and I guess I missed that and was focusing on the VO2max.
Btw, the study I saw discussing decrease in VO2 while increase in output was not about optimum cadence but suggested muscular modifications over time (fiber changes), let me see if I can find it.

Here, found the article and the blog: http://trainingscience.net/?page_id=618
http://www.ncbi.nlm.nih.gov/pubmed/19346977

Of course, that might not be normal physiological change.

EvgeniZyntx

I've had no problems with my FT4. It gives EXACTLY the same reading as the cardio equipment at my gym after I punch in my details It gave me about a 5000 odd calorie reading for my last marathon and my g'friend who is same age, similar build to me clocked similar results on her FT4 over a same distance. Check your battery, check that you have the strap on properly and the sensors are wet. Remember to adjust your weight in the settings as it changes too. Hope you find a better result.

This. I've only had mine for about a week but so far it's been right on gym equipment and other calorie calculators.

Which only demonstrates precision across instruments not accuracy. If they all use the same formula from one manufacturer and that formula gives rise to errors (notice I'm not saying it is wrong, that is something different, it can still be the best estimate.) then it is normal to see the same results. See Haybales thread for more info.

EvgeniZyntx

Well, there was a RS300X for sale at a nearby store (going out of business) so I picked it up. Here is a last data point for your discussion, Peter.

Two watches, one HRM strap.

My data: Age 46 MaxHR 189 VO2Max 47 Sitting HR 60 Actual weight 85 Kg
--
Exercise was running for 41 min - both watches gave MaxHR 179 (95%) Avr HR 164 (87%)

-- FT7 -- Weight set 145 Kg Calories 503
-- RS300X -- Weight set 85 Kg Calories 642

So, this is just a data point - I think Haybales describes above what is going on and I don't have much issues with the readings, even at the lower calorie burn - someone weighing 145 calories could not have run 10kph for 41 min at that average HR without being incredibly, incredibly fit.

I wasn't going to execute today's data gathering like that but I forgot to set the FT7 back to 85Kg.

All future comparisons will be more about what the two watches give at 85Kg with the same MaxHR. But that wil be a different thread.

heybales

Ok, for walking, I'd completely agree, and I guess I missed that and was focusing on the VO2max.
Btw, the study I saw discussing decrease in VO2 while increase in output was not about optimum cadence but suggested muscular modifications over time (fiber changes), let me see if I can find it.

Here, found the article and the blog: http://trainingscience.net/?page_id=618
http://www.ncbi.nlm.nih.gov/pubmed/19346977

Of course, that might not be normal physiological change.

At that high level of performance, where increases are going to be few and far between, I can see that. May have changed bike position, cadence, ect to improve DE. I love how much time the pro's spend in wind tunnels trying to balance between best position and power.

But I've always seen that there will be an upper limit to VO2max, large aspect is just genetic. Man is that massive, 75.

Here's the cadence article.
http://www.ncbi.nlm.nih.gov/pubmed/15503124

Interesting side-article for non-cyclist. Huh, that's why they pedal so slow.
http://www.ncbi.nlm.nih.gov/pubmed/19430807

Now, back to HRM part for topic police, I recall seeing a study that elite endurance athletes will actually have a decrease in their measured HRmax after a period of time, not that it keeps dropping, but less than measured in the past.

heybales

Well, there was a RS300X for sale at a nearby store (going out of business) so I picked it up. Here is a last data point for your discussion, Peter.

Two watches, one HRM strap.

My data: Age 46 MaxHR 189 VO2Max 47 Sitting HR 60 Actual weight 85 Kg
--
Exercise was running for 41 min - both watches gave MaxHR 179 (95%) Avr HR 164 (87%)

-- FT7 -- Weight set 145 Kg Calories 503
-- RS300X -- Weight set 85 Kg Calories 642

So, this is just a data point - I think Haybales describes above what is going on and I don't have much issues with the readings, even at the lower calorie burn - someone weighing 145 calories could not have run 10kph for 41 min at that average HR without being incredibly, incredibly fit.

I wasn't going to execute today's data gathering like that but I forgot to set the FT7 back to 85Kg.

All future comparisons will be more about what the two watches give at 85Kg with the same MaxHR. But that wil be a different thread.

Ohhhh cool - because the RS300X has the VO2max stat, right?

So, using an estimated height of 177.8 cm because I haven't seen your height mentioned, with your other stats.

I'd be curious first regarding correct stats on both that you have, and compare counts.

Then if the height is changed to 190, does that help things?

Then again, let me know true height before the second test to tweak correctly. I'm using the HRM tab in the spreadsheet. Tweaking the height so the VO2max calc hit's your VO2max of 47.

Post that thread link here please, your right, deserves it's own.

EvgeniZyntx

Height 179.5 but I round to 180 cm.
Yep it has the VO2max, sitting HR and max HR. I don't know if it uses sitting HR in Cal calcs.

What I'll do is set up two straps (Garmin vs Polar) and run the following HRM / gps against each other.
Garmin 800, 405, Polar FT7, RS300X, mapmyfitness - all at the same time.
My daughter has a FT4, so might toss that one into a test if she brings in back from college.

Maybe first test will be Thursday, that my next run.

peterdt

To those of you who say being heavier does not necessarily mean you will burn more calories please look at the following articles.

yes, there are variables, and the key is lean muscle mass. But the heavier you are the more energy it takes to move the mass. simple physics really.

http://articles.chicagotribune.com/1994-05-27/news/9405280087_1_sulfites-restaurant-salad-bars-burn

http://www.livestrong.com/article/516870-do-heavier-people-burn-more-calories-while-exercising/

peterdt

Here is another interesting article. I think the main point of it though is that HRM are better than Fitbit and other devises in measuring calorie consumption. It makes me wonder if all the fitbit devises are really quite useless for the most part. I've never owned one though.

But still, this does not answer the Polar FT7 calorie burn going down as weight increases.

http://www.wired.com/playbook/2012/08/fitness-trackers/

heybales

Height 179.5 but I round to 180 cm.
Yep it has the VO2max, sitting HR and max HR. I don't know if it uses sitting HR in Cal calcs.

What I'll do is set up two straps (Garmin vs Polar) and run the following HRM / gps against each other.
Garmin 800, 405, Polar FT7, RS300X, mapmyfitness - all at the same time.
My daughter has a FT4, so might toss that one into a test if she brings in back from college.

Maybe first test will be Thursday, that my next run.

If that's the model with a fitness test, it'll measure your sitting HR, and use it in an estimate of your VO2max. Their website has a FAQ on the study they tweaked, I use it in the spreadsheet too for VO2max estimate.

If it measured 60, it should estimate about 45.5.

Or you can manually enter it as you did.

To get that to 47 that you know already, you'd have to enter height of 190 cm.

But your tests first will be interesting.

heybales

To those of you who say being heavier does not necessarily mean you will burn more calories please look at the following articles.

yes, there are variables, and the key is lean muscle mass. But the heavier you are the more energy it takes to move the mass. simple physics really.

http://articles.chicagotribune.com/1994-05-27/news/9405280087_1_sulfites-restaurant-salad-bars-burn

http://www.livestrong.com/article/516870-do-heavier-people-burn-more-calories-while-exercising/

Here is another interesting article. I think the main point of it though is that HRM are better than Fitbit and other devises in measuring calorie consumption. It makes me wonder if all the fitbit devises are really quite useless for the most part. I've never owned one though.

But still, this does not answer the Polar FT7 calorie burn going down as weight increases.

http://www.wired.com/playbook/2012/08/fitness-trackers/

Well, we gotta separate 2 things though, what you are actually doing, and the HRM missing a stat trying to estimate your burn.

Indeed, if you weigh more, you burn more calories doing the same workload as someone lighter.

But, now throw the HR into the mix, and a device trying to estimate calories from HR.

The HRM with no VO2max is assuming because you weigh more, your VO2max is below avg.
But if you are in shape, and your low HR during a workout, of which it has no idea if you did an easy or heavy workload, is assumed to mean you didn't work that hard, therefore not many calories.

But if you are actually out of shape but lighter and better BMI, and still had a low HR because of going slower, it's assumed your VO2max is avg or better than avg, and you actually burned more calories than you really did.

That's why a great test of your HRM is treadmill walking up to 4mph with incline and decent HR. Machine and calculator much more accurate than HRM, and tell you how far off it is.

http://www.myfitnesspal.com/topics/show/774337-how-to-test-hrm-for-how-accurate-calorie-burn-is

The problem you found is at the upper reaches of weight, the assumptions of how bad the VO2max must be more than offset the increased calorie burns of the extra weight.

So a 300 lb person walking 4mph at 5% incline burns 1093 calories.
A 150 lb person burns 546 calories, almost half.
http://www.exrx.net/Calculators/WalkRunMETs.html

Now, from the HRM's point of view.
300 lb person 70 inches tall and assumed RHR of 60 has VO2max of 35.5, and that 60 min at 120 avgHR burns 870 calories. 200 shy.
The 150 lb person same stats has assumed VO2max of 48.3, and that workout burns 560 calories. Much closer.

But what if the guy got lighter totally from diet and didn't improve his VO2max actually better than 35.5. The HRM is reporting 560, and he lucked out and got decent estimate.
And what if at heavier weight his VO2max was actually better, already at 48.3? His burn reported 870.

And none of those values match what he actually burned.

Oh, and these figures are actually based on using a Polar funded study formula in a spreadsheet, that allows entering more stats than the cheaper Polar's.
www.braydenwm.com/calburn.htm

HRM tab, stats at the top, sections to help get the stats. Personal burn table at the bottom.
http://www.myfitnesspal.com/topics/show/813720-spreadsheet-bmr-tdee-deficit-macro-calcs-hrm-zones

heybales

Here is another interesting article. I think the main point of it though is that HRM are better than Fitbit and other devises in measuring calorie consumption. It makes me wonder if all the fitbit devises are really quite useless for the most part. I've never owned one though.

But still, this does not answer the Polar FT7 calorie burn going down as weight increases.

http://www.wired.com/playbook/2012/08/fitness-trackers/

For exercise beyond walking and jogging up to 6.3 mph or non-walking/jogging, without a doubt.

But up to that point, they can be decently accurate, as much as HRM anyway. Because they are measuring steps, figuring movement and pace, and using similar calc's as I posted above.

And they start with foundation of BMR, and estimate RMR from that. Non-sleeping non-moving is giving RMR calorie burn, sleeping is given BMR.

heybales

Found it. Polar probably uses something like the formula's studies like these come up with to use in the HRM's with no VO2max stat.

http://europepmc.org/abstract/MED/16540845

BMI (R = 0.80, SEE = 4.90 mL x kg(-1) x min(-1)) and valid with constant errors (CE) were > 1 mL x kg(-1) x min(-1) for VO2max < 30 and > 50 mL x kg(-1) x min(-1).

This is the method they use on the nicer watches that have a fitness test.

http://www.ncbi.nlm.nih.gov/pubmed/16168867

Other variables included gender, age, body mass index, resting heart rate, and self-reported physical activity levels.

EvgeniZyntx

Height 179.5 but I round to 180 cm.
Yep it has the VO2max, sitting HR and max HR. I don't know if it uses sitting HR in Cal calcs.

What I'll do is set up two straps (Garmin vs Polar) and run the following HRM / gps against each other.
Garmin 800, 405, Polar FT7, RS300X, mapmyfitness - all at the same time.
My daughter has a FT4, so might toss that one into a test if she brings in back from college.

Maybe first test will be Thursday, that my next run.

If that's the model with a fitness test, it'll measure your sitting HR, and use it in an estimate of your VO2max. Their website has a FAQ on the study they tweaked, I use it in the spreadsheet too for VO2max estimate.

If it measured 60, it should estimate about 45.5.

Or you can manually enter it as you did.

To get that to 47 that you know already, you'd have to enter height of 190 cm.

But your tests first will be interesting.

For the estimate of vo2max it uses a lying down test. And you can over-ride the value and enter you own.

EvgeniZyntx

Found it. Polar probably uses something like the formula's studies like these come up with to use in the HRM's with no VO2max stat.

http://europepmc.org/abstract/MED/16540845

BMI (R = 0.80, SEE = 4.90 mL x kg(-1) x min(-1)) and valid with constant errors (CE) were > 1 mL x kg(-1) x min(-1) for VO2max < 30 and > 50 mL x kg(-1) x min(-1).

This is the method they use on the nicer watches that have a fitness test.

http://www.ncbi.nlm.nih.gov/pubmed/16168867

Other variables included gender, age, body mass index, resting heart rate, and self-reported physical activity levels.

Nice, thanks!

twistedlefty

stumbled upon this thread,
weighed 302 when i joined.
after a couple weeks bought a polar ft7 because i had read reports that treadmills weren't accurate at reporting calories burned.
since then i've lost nearly 30 lbs and have just now realised i haven't been resetting my body weight on my hrm as i've been losing.
i started using it weighing 288 i believe and have logged every treadmill workout since buying the hrm. i've noticed that i need to work harder now to burn the same target calorie goal then i did when i started , but i assumed that would be the case.
http://www.myfitnesspal.com/blog/twistedlefty
question: is the ft7 faulty? is it accurate enough?i read the first few pages of this thread and it quickly lost me. could someone summarize?

heybales

stumbled upon this thread,
weighed 302 when i joined.
after a couple weeks bought a polar ft7 because i had read reports that treadmills weren't accurate at reporting calories burned.
since then i've lost nearly 30 lbs and have just now realised i haven't been resetting my body weight on my hrm as i've been losing.
i started using it weighing 288 i believe and have logged every treadmill workout since buying the hrm. i've noticed that i need to work harder now to burn the same target calorie goal then i did when i started , but i assumed that would be the case.
http://www.myfitnesspal.com/blog/twistedlefty
question: is the ft7 faulty? is it accurate enough?i read the first few pages of this thread and it quickly lost me. could someone summarize?

Those cheaper HRM's assume a fitness level matches a BMI level.

Meaning, bad BMI, bad fitness level. Good BMI, good fitness level. Both are actually bad assumptions, as many bad BMI people can be more fit than good BMI people.

Higher HR therefore means higher calorie burn when BMI is still bad.

But, if you are actually fit after 3 months with a bad BMI still, your HR doesn't have to beat as high to burn the same number of calories, if your weight stayed the same.

So now the HRM sees lower HR, and assumes less work, less calories.

Bad assumption.

You are burning less doing the exact same pace and incline if your weight went down. But the amount your HR goes down is more than that.

Here is self test you can do.

http://www.myfitnesspal.com/topics/show/774337-how-to-test-hrm-for-how-accurate-calorie-burn-is

You are probably burning more than you are being told, probably decently more.

And here is most accurate estimate of calories burned, you can compare weights to see the differences.
Oh, gross is what HRM would report, net is what you actually burned above and beyond just sitting still.

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

Your HR is going down because it's easier for your cardio system to burn the SAME amount of calories at equal effort.
Now, for a workout for the heart, you do indeed want higher HR.
Just like muscles that have gotten stronger, you have to increase the weight for it to still be a good workout.
For the heart, that means keeping the HR in a zone that may be more than your current muscles can do.

twistedlefty

thanks for the reply and explanation,
i was worried that the Heart rate being reported may be inaccurate.

so as i understand, i just need to keep my HR in the range that gives me results, not worry about the rest of it,

joslin2005

I have the polar ft4 and it's the same thing. It doesn't even make sense to me why a heavier person would burn LESS than a lighter person having the same HR.

heybales

I have the polar ft4 and it's the same thing. It doesn't even make sense to me why a heavier person would burn LESS than a lighter person having the same HR.

Read my reply 2 posts above yours for the reason why.

In reality you are exactly correct. Same pace, same incline, heavier would burn more.

But, your heavier person could be very fit, high VO2max, compared to lighter person with terrible VO2max.

So the cheaper Polar in those cases thinks the heavier person with low HR during the workout was NOT going hard, so smaller calorie burn. But the lighter person with high HR must have been going real hard, so big calorie burn.
Wrong on both accounts.

Or here is what happens with the same person.
In say 1 month of going nuts on cardio from doing nothing prior, they make great advancement and VO2max actually goes up decent amount from prior terrible number.
But their weight doesn't change. And they always set the treadmill to same speed instead of going faster even though it feels easier.

So HRM at first saw high HR, assumed big calorie burn. After a month it sees lower HR, so assumes smaller calorie burn.
Actually, you burned the same amount at same weight, same pace, ect. HRM is wrong.

This is where the myth that if you keep doing the same activity, you burn a whole lot less calories. Very untrue. As you weigh less, sure.
But increase the pace a tad more for lighter weight, same calorie burn. But HRM in that case still may think you are burning way less. Wrong.