Calorie Burn Question

Kekibird

On average my body burns 10 calories per minute when I'm exercising.

I can't complain because it's a good burn.

But I have noticed that on days when I feel like I push myself harder or I burn more, my numbers stay the same: 10 per minute.

I guess my question is: Can a body plateau on calories burned per minute?

Background: I do wear an HRM chest band and watch that is calibrated to my height, age, gender, weight and heart rate. My exercises can vary between Kettlebells, Zumba, cardio bootcamps, and Bosu ball so I do mix it up.

Just curious if anyone has info on this. I've been googling and haven't found the right information I'm looking for.

Thanks in advance MFP friends.

Katie

hpsnickers1

I'm curious on this too. I've done 3 days of The 30DS and burned pretty much the same amount of calories. It also is about 10 per minute going by my HRM (has the same options that yours does).

ProTFitness

The more fit you become the harder you have to work to get your HR up and keep it up. A good average is 10 calories a min. That means id your doing that for 60 min your should burn 600 calories. You have to consider warm up and cool down your heart rate will not be as high. Remeber the fitter you are the harder it will be to burn those calories because you recover HR is improving. Good Luck keep up the hard work

Kekibird

The more fit you become the harder you have to work to get your HR up and keep it up. A good average is 10 calories a min. That means id your doing that for 60 min your should burn 600 calories. You have to consider warm up and cool down your heart rate will not be as high. Remeber the fitter you are the harder it will be to burn those calories because you recover HR is improving. Good Luck keep up the hard work

Oof, I don't even want to think about that point because it's been a freakin' nightmare getting to *this* point and I feel like I'm working pretty darn hard. The idea that I'll have to start working HARDER makes me feel blah.... :ohwell:

Well, if 10 cal/min is a decent average, maybe I shouldn't be concerned when I feel like I've burned more?

Katie

Azdak

bump--I am at work and don't have time to answer this in detail now, but I want to get back to this later.

Short answer: you are burning more calories, but your HRM doesn't know that. It is one of the built-in shortcomings of using HRMs to estimate calories. I'll explain later.

Kekibird

bump--I am at work and don't have time to answer this in detail now, but I want to get back to this later.

Short answer: you are burning more calories, but your HRM doesn't know that. It is one of the built-in shortcomings of using HRMs to estimate calories. I'll explain later.

I'm interested to hear. I kinda kept in mind that my HRM could be the culprit. Can't trust technology 100%.

bbygrl5

bump.. I want to hear what Azdak has to say because he knows his stuff!

Azdak

OK--couldn't do this at work--too many people looking over my shoulder.

First of all, and I always have to start with this: heart rate monitors do NOT measure calories burned--not directly anyhow. They estimate calories burned based on the relationship between heart rate and oxygen uptake (or VO2). During steady-state cardio exercise, there is a relatively consistent relationship between heart rate and VO2, so the HRM can look at heart rate, figure out what percentage of your maximum heart rate you are working at, translate that % of heart rate max to a % of VO2 max and calculate calories.

Got it so far? The key is that the HRM has to be able to estimate your oxygen uptake from your heart rate, because that's how you calculate calories. Heart rate by itself doesn't mean anything--it's just a relative indicator.

That term--relative--is key to this discussion. Heart rate is a *relative* number. By that, I mean that the actual number --120, 130, 160, etc--doesn't mean very much. What percentage that is of your maximum heart rate--50%, 70%, 80%, etc--IS significant.

One of the fundamental physical changes that take place with exercise training is that the heart rate for any given submaximal workload with decrease. That's because your maximum fitness level has INcreased and now that workload represents a smaller percentage of your maximum. For example, you start an exercise program and running 5.0 mph represents 75% of your maximum. Your heart rate is 150 bpm. After several weeks of training, your maximum fitness level increases by, say, 15%-20%, Now, if you run 5.0 mph, your heart rate might only be 126 bpm. Why? Because now that workload only represents 63% of your maximum instead of 75%.

Here is where the error comes in. The energy cost (calories burned) of a workload is relatively fixed. In the above example, running 5.0 mph is a workload of 7.3 METs (a MET is a measurement of oxygen uptake). When you first starting running and going 5.0 mph was harder, the workload was 7.3 METs. Now that you are more fit, even though the workload is a lower % of your maximum and feels easier and your heart rate is lower, the workload (and thus the calories burned per minute per kg of body wt) is STILL 7.3 METs. What has changed is that your MAXIMUM has increased, therefore it feels easier.

The energy cost of an activity is FIXED, but the heart rate response is RELATIVE. Since the HRM doesn't know that your maximum fitness level has increased, it assumes that, since your heart rate is lower, you are now working at a LOWER workload, and thus estimates that you are burning fewer calories.

Since people have been conditioned by HRM manufacturers and the popular press and ignorant trainers to believe that heart rate and HRMs directly measure calories, this myth has arisen that, the longer you do any activity, the fewer calories you burn doing it. And people are running around doing odd things to try and "shock" their bodies into burning more calories.

So what to do with your HRM? Depends. Ideally, you should be able to update your VO2max in your HRM, so that the device calculates the percentage of a higher number. In the case mentioned above, ideally, the HRM could be programmed to know that your VO2 max increased from 9.7 METs to 11.7 METs, so that, even though running 5.0 mph is now 63% of your maximum, it is now 63% of 11.7, rather than 75% of 9.7, therefore the calories burned should stay relatively the same.

Some of the more advanced Polar models -- the F6, F11, RS300x, RS800x--allow you to manually enter your VO2 max (of course, you still have to be able to figure out what that number is, which is not easy for many people, but at least it's an option). Most Polar models above the F4 have the "Polar fitness test" which uses resting heart rate to estimate VO2 max. You would just retake the Polar fitness test and update your settings. That would probably be acceptable for someone just starting a program -- that person would be more likely to see significant decreases in resting heart rate with training. If you are a more experienced exerciser, I don't know how much more resting HR is going to drop. Suunto models can also track these changes and maybe some of the top end, newer Garmin models as well. If you don't have one of these monitors, I have no idea how or even if you can update these settings--which is why I don't recommend any of them (Timex, Mio, Omron, etc).

So, there you go--hopefully that's not too complicated.

It's one of the reasons why I always advise that people exercise caution when using HRM calorie numbers in their eating plans. Based on what I read here, I think people think these things are a lot more accurate than they are. I would advise that people never eat more than 50% of the exercise calories as measured by an HRM. Your risks of overeating are significant higher than any possible risks of adverse effects from undereating

rescuepete

Wow, @Azdak knows his stuff. I always wondered what that VO2 max setting was for and always skipped it. Now I just need to figure out how to gauge it. Also weird, I've been burning supposedly 1000+ calories a day, but I usually only eat about 500-600 of them. That also follows inline with @Azdak's reco. I need a smarty like that on my friend list -- sending him a req now.

The other thing to think about, Katie, is that your HRM is piss-poor at doing anything but cardio. So if you're doing strength training, don't even bother with it.

Kekibird

Thanks Azdak. That is a lot of info to take in and I think I got most of it.

I know that calorie burn calculated by HRM isn't perfect. And while I'm not looking for perfect, I am looking to get as close to realistic as possible so I feel balance in my exercise and eating.

Any suggestions? Stick with the HRM? Use MFP's calorie logging system? Are there any of options to calculating calories burned?

I do have a Polar F6, but it's about 2-3 years old. I've never set the "Own Zone" setting on it. As Pete said, I didn't know what it was or even how to set it.

Pete: Not sure exactly what constitutes strength training. I never do only ST but a mixture of ST/cardio to burn more. So I do use weights but not exclusively during my ST workout because I'm also doing some sort of cardio.

I guess now I'm looking for the best option to calculate my calories burned. And a simple way. Or an understanding of how to use my imperfect HRM to best calculate what I'm burning even if it's not quite on spot.

Katie

Azdak

Thanks Azdak. That is a lot of info to take in and I think I got most of it.

I know that calorie burn calculated by HRM isn't perfect. And while I'm not looking for perfect, I am looking to get as close to realistic as possible so I feel balance in my exercise and eating.

Any suggestions? Stick with the HRM? Use MFP's calorie logging system? Are there any of options to calculating calories burned?

I do have a Polar F6, but it's about 2-3 years old. I've never set the "Own Zone" setting on it. As Pete said, I didn't know what it was or even how to set it.

Pete: Not sure exactly what constitutes strength training. I never do only ST but a mixture of ST/cardio to burn more. So I do use weights but not exclusively during my ST workout because I'm also doing some sort of cardio.

I guess now I'm looking for the best option to calculate my calories burned. And a simple way. Or an understanding of how to use my imperfect HRM to best calculate what I'm burning even if it's not quite on spot.

Katie

I guess it depends on how fast you are progressing. Me, I'm old and I've been doing this for awhile, so unless I lose another 20 lbs I am probably going to be staying within 10% of where I am now--so it's not worth the bother to change my VO2 max every month. I did at the beginning of my program when my calories dropped way below some reference values I had and it did make a difference.

If you belong to a gym and they have Life Fitness treadmills, you could try doing the 5 min submax fitness test. That does a pretty good job. Or, you could try a field test, like the 12 min run test. Google "12 min run test" or "walk/run field test" and you should come up with some references, guidelines and scoring values. I think I saw reference to where the 12 min Run Test had been modified to account for people who can't run 12 minutes.

Another option, if your weight hasn't changed that much, would be to go back to an activity that recorded 10 cal/min and try to do it at the same perceived exertion or same actual workload. Change your VO2 max number in your Polar until it starts recording 10 cal/min at the now-lower heart rate. Don't increase VO2max by more than 5 .

To be honest, HRMs are no more than 80% accurate under the best of circumstances, so you might just bump up the VO2max number and go from there. You shouldn't be eating back all of your exercise calories anyhow (our methods of estimation are just too imprecise), so if you ate back 1/2 you would probably still be in good shape--taking in enough fuel to support your workouts, but still losing weight.

bsoxluvr

I'm so confused now! I asked my husband to get me a Polar HRM for Christmas...is it really worth it if even those aren't accurate?

Azdak

I'm so confused now! I asked my husband to get me a Polar HRM for Christmas...is it really worth it if even those aren't accurate?

It depends. HRMs are good for focusing your training efforts. That's their primary purpose. For certain activities, such as aerobic-based DVD workouts, some group classes, spinning, certain types of circuit training, they are still the best option--everything else is just a wild guess.

But, like any tool, they have to be used properly. And they are not as "precise" as many people make them out to be. HRMs are not "omniscient".

Now, let me swing back to the positive: 80% accuracy in limited situations is not necessarily bad. Nothing we do-- from estimating exercise calories to reading food labels, to logging on MFP--is any more accurate. The everyday measurement of human metabolism is not precise at all. So, 80% is about as good as you can expect.

If you don't have a good sense of how much activity burns how many calories, then a Polar HRM will most likely give you some important insights. Just realize that it is an interactive tool, not a precise measuring instrument. I mean, if it says you burn 500 calories in an hour 80% is only 80 calories each way. I don't know what your expectations are, but that small of an amount is relatively insignificant. And you wouldn't want to eat back 500 calories anyhow.

So, I didn't mean to mess up your Christmas plans, but people should have realistic expectations about what these things can do. Like I said, HRMs can be great tools--I wear one for practically every workout and have done so for years.

Kekibird

I guess it depends on how fast you are progressing. Me, I'm old and I've been doing this for awhile, so unless I lose another 20 lbs I am probably going to be staying within 10% of where I am now--so it's not worth the bother to change my VO2 max every month. I did at the beginning of my program when my calories dropped way below some reference values I had and it did make a difference.

If you belong to a gym and they have Life Fitness treadmills, you could try doing the 5 min submax fitness test. That does a pretty good job. Or, you could try a field test, like the 12 min run test. Google "12 min run test" or "walk/run field test" and you should come up with some references, guidelines and scoring values. I think I saw reference to where the 12 min Run Test had been modified to account for people who can't run 12 minutes.

Another option, if your weight hasn't changed that much, would be to go back to an activity that recorded 10 cal/min and try to do it at the same perceived exertion or same actual workload. Change your VO2 max number in your Polar until it starts recording 10 cal/min at the now-lower heart rate. Don't increase VO2max by more than 5 .

To be honest, HRMs are no more than 80% accurate under the best of circumstances, so you might just bump up the VO2max number and go from there. You shouldn't be eating back all of your exercise calories anyhow (our methods of estimation are just too imprecise), so if you ate back 1/2 you would probably still be in good shape--taking in enough fuel to support your workouts, but still losing weight.

Bummer it's so complex. I think I'm lost on the whole VO2 thing.

I think I'll just take my calorie burn with a grain of salt (har har) and just stick with whatever I'm doing and hope for the best. I try to eat healthy and balance and I move when I can.

It's better than nothing.

Katie

Azdak

I guess it depends on how fast you are progressing. Me, I'm old and I've been doing this for awhile, so unless I lose another 20 lbs I am probably going to be staying within 10% of where I am now--so it's not worth the bother to change my VO2 max every month. I did at the beginning of my program when my calories dropped way below some reference values I had and it did make a difference.

If you belong to a gym and they have Life Fitness treadmills, you could try doing the 5 min submax fitness test. That does a pretty good job. Or, you could try a field test, like the 12 min run test. Google "12 min run test" or "walk/run field test" and you should come up with some references, guidelines and scoring values. I think I saw reference to where the 12 min Run Test had been modified to account for people who can't run 12 minutes.

Another option, if your weight hasn't changed that much, would be to go back to an activity that recorded 10 cal/min and try to do it at the same perceived exertion or same actual workload. Change your VO2 max number in your Polar until it starts recording 10 cal/min at the now-lower heart rate. Don't increase VO2max by more than 5 .

To be honest, HRMs are no more than 80% accurate under the best of circumstances, so you might just bump up the VO2max number and go from there. You shouldn't be eating back all of your exercise calories anyhow (our methods of estimation are just too imprecise), so if you ate back 1/2 you would probably still be in good shape--taking in enough fuel to support your workouts, but still losing weight.

Bummer it's so complex. I think I'm lost on the whole VO2 thing.

I think I'll just take my calorie burn with a grain of salt (har har) and just stick with whatever I'm doing and hope for the best. I try to eat healthy and balance and I move when I can.

It's better than nothing.

Katie

It's more than "better than nothing". I'm sorry, I go back and forth on this question--on the one hand I don't want people to have unrealistic expectations or inaccurate information; OTOH, sometimes the truth can be discouraging.

But I read things all the time like a post earlier today where a guy was trying to eat back something like 1200 extra calories because of some goofy number on an HRM.

And I like data, so I tend to go deep into the details--maybe too deep sometimes.

Just don't worry if you see the calorie numbers decreasing when you are doing the same activity--your actual calorie expenditure is probably not going down.

Kekibird

I think my original line of questioning was to find out if a body has a max calorie burn. Like can a body have a limit they hit and it levels out, like hitting a ceiling with no ability to go higher. And I felt that mine maxed at 10 cal/hour.

But, because there really isn't a true method of measuring calories burned, I think it's kind of a moot point now.

Anywho....I'll just keep on trucking.

Katie

bsoxluvr

Thank you for all of your help, Azdak! The information is much appreciated.

mkingraham

bump- very interesting discussion

lorettatat

BUMP