Max HR vs Calories burned

jfinnivan

I got my wife a Polar FT40 HRM, and she's been using it to get calories burned for walking. She did the built-in fitness test, but used the default Max heart rate, which was 167. She used the HRM for a 5 mile walk, walking at 4mph. The calories burned, after subtracting the BRM was 460 calories.
The other day, we tried, informally, to get a more accurate Max heart rate by running as fast as we could. Her recorded max was 198, so until we go through the formal procedure, we set her Max at 200. Today, she did the walk again, and the calories burned were now 260. This seems like a very low number for walking for 75 minutes at 4 mph. I realize the Max heart rate will affect the results, but this seems extreme. She is 5' 10" tall, and weighs 158lbs. Any thoughts? Are these numbers reasonable?

ChristyP0303

To get your max heartrate, you subtract your age from 220. That is your max heartrate.

Pete_Mann

I agree with Kitkat. You dont want to get your max heart rate by running your heart up. That's like trying to find landmines by stamping your feet. The accepted max heart rate is 220-Age.

Do you have to subtract the BRM? I never have with mine.

ilikejam33

Here is the formula recommended to me by my doctor, it is also sited inthe running room book,

I'm attaching the ehow website becasue its the same formula but ehow just lays it out a little easier to look at.

Also it is recommended you re-calculate evey 10lbs lost for the most accuracy.

http://www.wikihow.com/Calculate-Your-Target-Heart-Rate

Keefypoos

220 for a man
226 for a woman
then subtract age

jfinnivan

From what I've read, you need to subtract your BMR to get an accurate number, since the HRM is calculating total calories burned, which includes BRM.

Also, I've seen several sites that claim that everybody has their own max heart rate:

http://www.howtobefit.com/determine-maximum-heart-rate.htm

Since the HRM is using the max value (and VOmax) to calculate calories burned, you'd want to get the most accurate number possible. Maybe a call to Polar to get their take on it would help.
I think the best way to get your max heart rate is to go to a doctor and get a cardiac stress test.

erickirb

I agree with Kitkat. You dont want to get your max heart rate by running your heart up. That's like trying to find landmines by stamping your feet. The accepted max heart rate is 220-Age.

Do you have to subtract the BRM? I never have with mine.

You do have to subtract BMR to get calories burned from walking as some of the calories on your HRM would have been burned had you not walked. The HRM calculates total calories burned, if you enter the cals burned into something like MFP you should back out maintenance calories during that period as MFP already accounts for those in your caloric allowance for each day.

Azdak

You did the right thing by trying to get true HRmax. Unfortunately, it sounds like you did not get the right results.

There are established energy prediction equations for walking and running that are reasonably accurate. Given you wife's weight (72 kg), the intensity of walking 4.0 mph (4.06 METs), and the duration of exercise (1.25 hr), total calories expended is calculated at 365 calories.

It must always be mentioned that Polar does not measure actual workload intensity. It makes assumptions based on heart rate. If for whatever reason heart rate response doesn't match the expected response calculated by the Polar algorithms, you have a disconnect.

Polar is very secretive about how they determine their calculations. I have found that even when they explain things in English, it's still not very clear. I have read other analyses that claim that Polar tends to underestimate calories at lower intensities. They certainly do for me.

You could try doing the fitness test to see if that changes anything. You might also try looking for some information on the Polar website.

http://www.polar.fi/en/training_with_polar/training_articles

This section has some articles on training that may or may not be relevant. There are user forums that have a lot of information as well--I suspect your question has been raised before, or you can post it and see what responses you get.

Azdak

From what I've read, you need to subtract your BMR to get an accurate number, since the HRM is calculating total calories burned, which includes BRM.

Also, I've seen several sites that claim that everybody has their own max heart rate:

http://www.howtobefit.com/determine-maximum-heart-rate.htm

Since the HRM is using the max value (and VOmax) to calculate calories burned, you'd want to get the most accurate number possible. Maybe a call to Polar to get their take on it would help.
I think the best way to get your max heart rate is to go to a doctor and get a cardiac stress test.

Unfortunately a medical "stress test" has become virtually useless when it comes to determining any performance data. Physiologists have often been replaced by techs who just push buttons and, not only do they encourage people to hold on to the handrails, very few will ever push you to a max level. I've had tests shut down on me when I was verbally pleading with them to let me continue (my HR was still lower than when I exercise). They just don't want to take the risk of the extra paperwork if something goes outside the routine.

If you want a true max test you will have to find a performance lab at a university or somewhere that does testing for the public.

jfinnivan

You did the right thing by trying to get true HRmax. Unfortunately, it sounds like you did not get the right results.

There are established energy prediction equations for walking and running that are reasonably accurate. Given you wife's weight (72 kg), the intensity of walking 4.0 mph (4.06 METs), and the duration of exercise (1.25 hr), total calories expended is calculated at 365 calories.

It must always be mentioned that Polar does not measure actual workload intensity. It makes assumptions based on heart rate. If for whatever reason heart rate response doesn't match the expected response calculated by the Polar algorithms, you have a disconnect.

Polar is very secretive about how they determine their calculations. I have found that even when they explain things in English, it's still not very clear. I have read other analyses that claim that Polar tends to underestimate calories at lower intensities. They certainly do for me.

You could try doing the fitness test to see if that changes anything. You might also try looking for some information on the Polar website.

http://www.polar.fi/en/training_with_polar/training_articles

This section has some articles on training that may or may not be relevant. There are user forums that have a lot of information as well--I suspect your question has been raised before, or you can post it and see what responses you get.

I'm confused now. I thought the max heart rate is the max rate your heart will beat for a given activity. When my wife ran as fast as she could, the HRM recorded a value of 198. Is 200 not a good guess based upon that? If 200 is a good guess, then is the HRM giving a bad calculated calories burned?

Azdak

You did the right thing by trying to get true HRmax. Unfortunately, it sounds like you did not get the right results.

There are established energy prediction equations for walking and running that are reasonably accurate. Given you wife's weight (72 kg), the intensity of walking 4.0 mph (4.06 METs), and the duration of exercise (1.25 hr), total calories expended is calculated at 365 calories.

It must always be mentioned that Polar does not measure actual workload intensity. It makes assumptions based on heart rate. If for whatever reason heart rate response doesn't match the expected response calculated by the Polar algorithms, you have a disconnect.

Polar is very secretive about how they determine their calculations. I have found that even when they explain things in English, it's still not very clear. I have read other analyses that claim that Polar tends to underestimate calories at lower intensities. They certainly do for me.

You could try doing the fitness test to see if that changes anything. You might also try looking for some information on the Polar website.

http://www.polar.fi/en/training_with_polar/training_articles

This section has some articles on training that may or may not be relevant. There are user forums that have a lot of information as well--I suspect your question has been raised before, or you can post it and see what responses you get.

I'm confused now. I thought the max heart rate is the max rate your heart will beat for a given activity. When my wife ran as fast as she could, the HRM recorded a value of 198. Is 200 not a good guess based upon that? If 200 is a good guess, then is the HRM giving a bad calculated calories burned?

Sorry, didn't mean to confuse.

The 200 is as good a guess as any, and certainly more accurate than 167.

I tried to explain that, per established and validated equations for predicting energy expenditure (calories burned) for walking, the answer was "yes" the display of 260 on the HRM was likely way off.

The third question is then "why is it off" and that is harder to explain. It could be that there are built-in inaccuracies in the way Polar estimates calories or it could be something else in the way the watch is set up.

My attempts to give explanations on the "why" seem to have been confusing, so I will leave it at that for now. Again, if you are really interested, you might visit the sites I listed for more answers.

crisanderson27

Also, I've seen several sites that claim that everybody has their own max heart rate:

It is absurd to think that a-one-size-fits-all formula would be accurate for each person. The 220-Age isn't going to tell you exactly what you can get your heart up to, because like every other human feature, heart capacity is distributed over the bell curve- but what it does in give you a number to safely work with when using the monitor. Because you are aiming to keep the heart between a set percentage of your max effort, you have to have something to use as a max!

If you are curious, or masochisitc, the preferred max heart rate test of track coaches is as follows. Go to your local track, warm up, stretch. Then you will run 2 miles; the first mile at moderate effort, then each of the next 4 laps, increase the effort until on the last lap you are gutting it out as hard as you can. This tends to get you to your max. Still- it's mostly a novelty just to brag about. Example - even though I'm 29, I got my heart up to 212bmp last week.

For finding max heartrate, P90X recommends doing jumping jacks at a fast pace for 1 minute 30 seconds, then 30 seconds max effort. They want you to record the max...then record the number every minute after for 4 minutes...for later comparison.

No clue if this is medically accurate...just throwing it out there.

Azdak

Also, I've seen several sites that claim that everybody has their own max heart rate:

It is absurd to think that a-one-size-fits-all formula would be accurate for each person. The 220-Age isn't going to tell you exactly what you can get your heart up to, because like every other human feature, heart capacity is distributed over the bell curve- but what it does in give you a number to safely work with when using the monitor. Because you are aiming to keep the heart between a set percentage of your max effort, you have to have something to use as a max!

If you are curious, or masochisitc, the preferred max heart rate test of track coaches is as follows. Go to your local track, warm up, stretch. Then you will run 2 miles; the first mile at moderate effort, then each of the next 4 laps, increase the effort until on the last lap you are gutting it out as hard as you can. This tends to get you to your max. Still- it's mostly a novelty just to brag about. Example - even though I'm 29, I got my heart up to 212bmp last week.

For finding max heartrate, P90X recommends doing jumping jacks at a fast pace for 1 minute 30 seconds, then 30 seconds max effort. They want you to record the max...then record the number every minute after for 4 minutes...for later comparison.

No clue if this is medically accurate...just throwing it out there.

In re-reading my post, I realize there is a hipocracy in making fun of the idea that a single formula cuold predict max HR, then offer a one size fits all test that does the same!

I think any test, such as the jumping jacks, is going to depend on how fit your heart is! (What I meant to say before, but got lost in a track workout haha) - I'd personally be doing JJ's for a while, if ever, to get my heart-rate up to where it is at the end of a race or hard run.

The 220 minus age is probably good enough for most applications.

It's not so much a question of how fit the heart is, it's how willing someone is to push themselves to max effort and if they are even able to do it.

An untrained person is likely going to experience muscle fatigue before they reach HR max. Or they will not be able to sustain the effort because it is too uncomfortable.

As was mentioned earlier, any formula for estimating HRmax will have a standard of error, and most are in the 10-12 beats/min range. So that gives a considerable number of people who are 20-30 beats/min away from the calculated figure. The actual numbers I believe are even more than that. I hardly ever bother to even calculate "target heart rate" anymore. I used to be able to come up with good heart rate numbers when I was giving my clients their stress tests, because I would make it a true performance test. But any more, I see so many people (esp females) whose HRs bear no resemblance to their age-predicted numbers, that I rely mainly on perceived exertion for my recreational exercisers.

jfinnivan

You did the right thing by trying to get true HRmax. Unfortunately, it sounds like you did not get the right results.

There are established energy prediction equations for walking and running that are reasonably accurate. Given you wife's weight (72 kg), the intensity of walking 4.0 mph (4.06 METs), and the duration of exercise (1.25 hr), total calories expended is calculated at 365 calories.

It must always be mentioned that Polar does not measure actual workload intensity. It makes assumptions based on heart rate. If for whatever reason heart rate response doesn't match the expected response calculated by the Polar algorithms, you have a disconnect.

Polar is very secretive about how they determine their calculations. I have found that even when they explain things in English, it's still not very clear. I have read other analyses that claim that Polar tends to underestimate calories at lower intensities. They certainly do for me.

You could try doing the fitness test to see if that changes anything. You might also try looking for some information on the Polar website.

http://www.polar.fi/en/training_with_polar/training_articles

This section has some articles on training that may or may not be relevant. There are user forums that have a lot of information as well--I suspect your question has been raised before, or you can post it and see what responses you get.

I'm confused now. I thought the max heart rate is the max rate your heart will beat for a given activity. When my wife ran as fast as she could, the HRM recorded a value of 198. Is 200 not a good guess based upon that? If 200 is a good guess, then is the HRM giving a bad calculated calories burned?

Sorry, didn't mean to confuse.

The 200 is as good a guess as any, and certainly more accurate than 167.

I tried to explain that, per established and validated equations for predicting energy expenditure (calories burned) for walking, the answer was "yes" the display of 260 on the HRM was likely way off.

The third question is then "why is it off" and that is harder to explain. It could be that there are built-in inaccuracies in the way Polar estimates calories or it could be something else in the way the watch is set up.

My attempts to give explanations on the "why" seem to have been confusing, so I will leave it at that for now. Again, if you are really interested, you might visit the sites I listed for more answers.

So, what this is telling me is that using a max heart rate value of 200 causes the Polar FT40 to give inaccurate calorie readings. I called Polar, and they claimed that using the FT40's "Fitness Test" will set the numbers properly to give an accurate calorie burn number. The Max heart rate the fitness test set was 167, which is exactly 220-age. Hmmm. I bought the HRM simply for calorie burn values for MFP, and now I don't know what to trust anymore. The documents at the Polar site state that to get a more accurate max HR number, have a clinical test done. If we did this, I expect we'll see a number close to 200, which brings us back to the low calorie number with the FT40. I'm starting to believe that unless you're textbook average, the HRMs are pretty useless for calorie calculations.

erickirb

[ I'm starting to believe that unless you're textbook average, the HRMs are pretty useless for calorie calculations.

Maybe so but still better than the other forms of estimation such as the MFP database or the gym machines. If you are caught up in finding the max HR maybe split the difference between 198 and 167 and use 183 instead.

And FYI, it is not BMR calories that you should back out, but rather maintenance calories, as MFP assumes you would be doing something other than in a coma if you did not workout. BMR cals are just what you would burn in a coma like state. To get your maintenance calories go to goals, under My Home. Look for calories burned from normal daily activity, that is your maintenance calories.

If you were using your HRM at rest to get cals burned at rest, be aware that that would overestimate your resting burn, as the equation in the HRM calculates calories assuming you are moving and working out and are only accurate when your HR is elevated due to activity for this reason.

Azdak

You did the right thing by trying to get true HRmax. Unfortunately, it sounds like you did not get the right results.

There are established energy prediction equations for walking and running that are reasonably accurate. Given you wife's weight (72 kg), the intensity of walking 4.0 mph (4.06 METs), and the duration of exercise (1.25 hr), total calories expended is calculated at 365 calories.

It must always be mentioned that Polar does not measure actual workload intensity. It makes assumptions based on heart rate. If for whatever reason heart rate response doesn't match the expected response calculated by the Polar algorithms, you have a disconnect.

Polar is very secretive about how they determine their calculations. I have found that even when they explain things in English, it's still not very clear. I have read other analyses that claim that Polar tends to underestimate calories at lower intensities. They certainly do for me.

You could try doing the fitness test to see if that changes anything. You might also try looking for some information on the Polar website.

http://www.polar.fi/en/training_with_polar/training_articles

This section has some articles on training that may or may not be relevant. There are user forums that have a lot of information as well--I suspect your question has been raised before, or you can post it and see what responses you get.

I'm confused now. I thought the max heart rate is the max rate your heart will beat for a given activity. When my wife ran as fast as she could, the HRM recorded a value of 198. Is 200 not a good guess based upon that? If 200 is a good guess, then is the HRM giving a bad calculated calories burned?

Sorry, didn't mean to confuse.

The 200 is as good a guess as any, and certainly more accurate than 167.

I tried to explain that, per established and validated equations for predicting energy expenditure (calories burned) for walking, the answer was "yes" the display of 260 on the HRM was likely way off.

The third question is then "why is it off" and that is harder to explain. It could be that there are built-in inaccuracies in the way Polar estimates calories or it could be something else in the way the watch is set up.

My attempts to give explanations on the "why" seem to have been confusing, so I will leave it at that for now. Again, if you are really interested, you might visit the sites I listed for more answers.

So, what this is telling me is that using a max heart rate value of 200 causes the Polar FT40 to give inaccurate calorie readings. I called Polar, and they claimed that using the FT40's "Fitness Test" will set the numbers properly to give an accurate calorie burn number. The Max heart rate the fitness test set was 167, which is exactly 220-age. Hmmm. I bought the HRM simply for calorie burn values for MFP, and now I don't know what to trust anymore. The documents at the Polar site state that to get a more accurate max HR number, have a clinical test done. If we did this, I expect we'll see a number close to 200, which brings us back to the low calorie number with the FT40. I'm starting to believe that unless you're textbook average, the HRMs are pretty useless for calorie calculations.

Well, as anyone who has read my posts knows, I have always advised caution with HRM calorie numbers. At best they are maybe 80% accurate. The problem is that they don't measure anything directly except heart rate. All of the calorie estimates are derived from mathematical relationships between HR behavior in groups under certain exercise conditions. Now the guys at Polar squeeze every last bit of manipulative data they can out of this--they been doing it for years--so it's probably as good as it can be. But I think there is just too much variance among individuals in different circumstances to come up with a "one formula fits all" approach.

You have to decide whether 80% accuracy during aerobic exercise, and pretty much 0% accuracy during strength training and resting activities is good enough for you. One could argue that it is. In most cases the difference will not be that significant. Anyone who would "eat back" 100%of calories based on an HRM readout is not following the best strategy.

jfinnivan

Thanks for all the great replies. Maybe it's because I'm an engineer, but I'm really trying to get as accurate a number as I can.