HRM Calorie Counts --Some Real World Data (uber long post)
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Azdak
Posts: 8,281 Member
I have addressed this topic numerous times before, but, with a new HRM and the advances in activity tracking sites, I have a better real-world example.
Summary: I will be showing the shortcomings of HRM calorie counts during aerobic exercise and the key role that VO2 max plays in determining those counts. I will be showing three workouts in which aerobic workload increased, but HRM calorie count decreased, and the various reasons why that occurred. So if you like this kind of technical detail, follow along.
Disclaimer: this is not an "anti Polar" or "anti HRM" post. I have used Polar HRM products for over 20 years and find them very useful for training. This is just to point out some of the issues for HRM calorie counts for anyone who is interested.
So I just got a new Polar V800. As always, I purchased about 5x as much technology as I'll ever use, but I love data and with the Polar Flow app, I now have graphs galore! Here are three similar workouts I did in February.
Feb 5 2016: 60-minute incline walk. Treadmill calories: 900 Polar Cal: 875 Avg HR: 132
Feb 20 2016: 58-minute run/walk (total running 32 min). Treadmill calories: 1000 Polar Cal: 858 Avg HR: 133
Feb 24 2016: 54-minute run/walk (total running 42 min). Treadmill calories: 1000 Polar Cal: 791
Avg HR 133. (Elevated HR at start was artifact from HR strap contact).
(Please note that I kicked *kitten* on the 2/24 workout, lowering my 1000 calorie time by 4 minutes in 4 days).
Sorry, back to the discussion. So you will notice that, while my performance increased dramatically according to the treadmill count (Calories/minute increased by 23% in 19 days), the Polar calorie count actually went down--noticeably.
Was this due to decreased weight? No really -- I probably lost 6 lbs during that time (and I update my weight on the HRM daily). That would affect the numbers a little bit, but not much.
The key is looking at my average HR -- it was the same for each workout. Since the Polar only monitors HR, it assumed I was working at the same level, only for fewer minutes. But, based on what I was able to accomplish, my performance clearly improved.
Let's revisit how HRMs estimate exercise calories:
Calorie expenditure is determine by how much oxygen your body uses--your "oxygen uptake" or VO2. The more oxygen you consume (i.e. higher VO2), the more calories you burn (given that weight is unchanged).
Aerobic workloads have a relatively fixed oxygen uptake. For example, the VO2 for walking 3 mph is 10.5 ml/kg/min, for running 6 mph approx 35 ml/kg/min. These oxygen uptakes are the same for most people--they are not greatly affected by age, gender, height, or fitness level.
It's important to note that treadmills calculate calories completely differently than HRMs--in some ways more accurately. For workouts like walking or running, or walking/running on a treadmill, there are relatively simple, validated equations for calculating the VO2, and thus the calorie burn. They have their own margin of error, but if my treadmill says I burned 15 cal/min on one workout (2/5) and 18.5 cal/min (2/24) on another, that represents a substantial increase in both aerobic work and calories burned, even if those actual numbers are not 100% accurate.
Yet that performance increase did not show up in my HRM numbers. Why?
HRM calorie counts are based on the fact that, during aerobic exercise, there is a consistent relationship between heart rate (HR) and oxygen uptake (VO2). If intensity and VO2 go up, so does heart rate. If they go down, HR goes down as well. (You can clearly see that in the HR graphs for my workouts, since they were interval-type workouts alternating higher effort and lower effort).
Since HRMs do not measure oxygen uptake, they CANNOT and do not measure calorie burn directly. That's a crucial point. HRMs do not measure calories. They measure heart rate.
If there is a consistent relationship between HR and VO2, then heart rate can be used to estimate VO2 and, thus, calorie expenditure. However in order to do that, you need a scale--not a weight scale, but a range of numbers for the HRM to relate to.
Your exercising heart rate range is consistent for the most part. Once someone has been exercising for a while--especially as long as I have--heart rate is not going to change dramatically. My resting heart rate is 46-48 and my HRmax is around 160-165. The HR max is not going to change, and my HR rest can't go much lower, so my HR reserve of around 115 bpm is pretty consistent. So, for me, a heart rate of 133 is going to represent about 75% of my HR reserve. As you can see from the graphs, that was a consistent response. However the workloads I was able to achieve and the total work performed was significantly different and that's because that, while your HR response follows a fixed range....
VO2 max (your maximum ability to use oxygen) DOES change over time--either with training or inactivity. So that changes the "scale".
Let's say my VO2 max is 35 and I am working at that 75% effort. That means that my VO2 is 26.25 ml/kg/min (75% of the VO2 max of 35). At that effort level, my calorie burn is roughly 13 calories per minute, and the HRM will reflect that.
However, if I increase that VO2 max to 42 and am working at the same 75% effort (remember, I'll have the same heart rate, since neither my HRmax nor my HRrest have changed), my VO2 is now 31.5 mi/kg/min and my calorie burn is roughly 15.9 cal/min.
Unless the HRM knows that my VO2 max is now 42, it will still give me the lower reading--and that is exactly what happened in those 3 workouts.
So the question is: how do you determine VO2 max? And how do you update your HRM?
Well, that's the tricky part. Determining VO2 max is not easy. It requires a laboratory test that is not readily accessible to the average person (plus, it's very strenuous and not everyone can even do it). Some Polar models have a "fit test" that gives you a VO2max, but that is based on resting HR, and I am skeptical of its accuracy. When I did a test on myself around 2/20, it came up with a number of 35 which, if true, would mean it was aerobically impossible for me to have done the workouts I did.
There are other submax and field tests you and do to estimate VO2 max. (ex: 12 min Cooper run test). Field tests are problematic because they require consistent effort and a peak performance that not everyone can do. Life Fitness treadmills have a 5 min walk test that is accessible to any user that is not bad--but it uses heart rate response to gauge effort so if your HRmax is less or higher than the "220-age" estimate, the VO2max score will be way off.
If you do have a Polar HRM with the "fit test" feature, you can take the test, and then refuse the score it gives you--then it gives you the option to enter your own score. With the V800, you can enter a VO2 max via the Polar Flow website w/out taking the test--not sure if that is available to everyone.
So in summary: HRM calorie counts are based on heart rate and VO2 max, not on the actual workload being performed. Exercise machines measure the actual workload and, if there are valid prediction equations for that type of machine, can use workload to estimate calories as reliably as an HRM. For maximum accuracy in calorie counts with an HRM, the HRM must be able to determine your aerobic fitness level, preferably VO2 max. If it cannot do that, I have no idea how they calorie counts can maintain any semblance of accuracy over time. Some Polar HRMs allow you to take a test to estimate VO2 max and/or input it manually. A more accurate VO2 number programmed into your HRM will result in a more accurate calorie estimate.
Summary: I will be showing the shortcomings of HRM calorie counts during aerobic exercise and the key role that VO2 max plays in determining those counts. I will be showing three workouts in which aerobic workload increased, but HRM calorie count decreased, and the various reasons why that occurred. So if you like this kind of technical detail, follow along.
Disclaimer: this is not an "anti Polar" or "anti HRM" post. I have used Polar HRM products for over 20 years and find them very useful for training. This is just to point out some of the issues for HRM calorie counts for anyone who is interested.
So I just got a new Polar V800. As always, I purchased about 5x as much technology as I'll ever use, but I love data and with the Polar Flow app, I now have graphs galore! Here are three similar workouts I did in February.
Feb 5 2016: 60-minute incline walk. Treadmill calories: 900 Polar Cal: 875 Avg HR: 132
Feb 20 2016: 58-minute run/walk (total running 32 min). Treadmill calories: 1000 Polar Cal: 858 Avg HR: 133
Feb 24 2016: 54-minute run/walk (total running 42 min). Treadmill calories: 1000 Polar Cal: 791
Avg HR 133. (Elevated HR at start was artifact from HR strap contact).
(Please note that I kicked *kitten* on the 2/24 workout, lowering my 1000 calorie time by 4 minutes in 4 days).
Sorry, back to the discussion. So you will notice that, while my performance increased dramatically according to the treadmill count (Calories/minute increased by 23% in 19 days), the Polar calorie count actually went down--noticeably.
Was this due to decreased weight? No really -- I probably lost 6 lbs during that time (and I update my weight on the HRM daily). That would affect the numbers a little bit, but not much.
The key is looking at my average HR -- it was the same for each workout. Since the Polar only monitors HR, it assumed I was working at the same level, only for fewer minutes. But, based on what I was able to accomplish, my performance clearly improved.
Let's revisit how HRMs estimate exercise calories:
Calorie expenditure is determine by how much oxygen your body uses--your "oxygen uptake" or VO2. The more oxygen you consume (i.e. higher VO2), the more calories you burn (given that weight is unchanged).
Aerobic workloads have a relatively fixed oxygen uptake. For example, the VO2 for walking 3 mph is 10.5 ml/kg/min, for running 6 mph approx 35 ml/kg/min. These oxygen uptakes are the same for most people--they are not greatly affected by age, gender, height, or fitness level.
It's important to note that treadmills calculate calories completely differently than HRMs--in some ways more accurately. For workouts like walking or running, or walking/running on a treadmill, there are relatively simple, validated equations for calculating the VO2, and thus the calorie burn. They have their own margin of error, but if my treadmill says I burned 15 cal/min on one workout (2/5) and 18.5 cal/min (2/24) on another, that represents a substantial increase in both aerobic work and calories burned, even if those actual numbers are not 100% accurate.
Yet that performance increase did not show up in my HRM numbers. Why?
HRM calorie counts are based on the fact that, during aerobic exercise, there is a consistent relationship between heart rate (HR) and oxygen uptake (VO2). If intensity and VO2 go up, so does heart rate. If they go down, HR goes down as well. (You can clearly see that in the HR graphs for my workouts, since they were interval-type workouts alternating higher effort and lower effort).
Since HRMs do not measure oxygen uptake, they CANNOT and do not measure calorie burn directly. That's a crucial point. HRMs do not measure calories. They measure heart rate.
If there is a consistent relationship between HR and VO2, then heart rate can be used to estimate VO2 and, thus, calorie expenditure. However in order to do that, you need a scale--not a weight scale, but a range of numbers for the HRM to relate to.
Your exercising heart rate range is consistent for the most part. Once someone has been exercising for a while--especially as long as I have--heart rate is not going to change dramatically. My resting heart rate is 46-48 and my HRmax is around 160-165. The HR max is not going to change, and my HR rest can't go much lower, so my HR reserve of around 115 bpm is pretty consistent. So, for me, a heart rate of 133 is going to represent about 75% of my HR reserve. As you can see from the graphs, that was a consistent response. However the workloads I was able to achieve and the total work performed was significantly different and that's because that, while your HR response follows a fixed range....
VO2 max (your maximum ability to use oxygen) DOES change over time--either with training or inactivity. So that changes the "scale".
Let's say my VO2 max is 35 and I am working at that 75% effort. That means that my VO2 is 26.25 ml/kg/min (75% of the VO2 max of 35). At that effort level, my calorie burn is roughly 13 calories per minute, and the HRM will reflect that.
However, if I increase that VO2 max to 42 and am working at the same 75% effort (remember, I'll have the same heart rate, since neither my HRmax nor my HRrest have changed), my VO2 is now 31.5 mi/kg/min and my calorie burn is roughly 15.9 cal/min.
Unless the HRM knows that my VO2 max is now 42, it will still give me the lower reading--and that is exactly what happened in those 3 workouts.
So the question is: how do you determine VO2 max? And how do you update your HRM?
Well, that's the tricky part. Determining VO2 max is not easy. It requires a laboratory test that is not readily accessible to the average person (plus, it's very strenuous and not everyone can even do it). Some Polar models have a "fit test" that gives you a VO2max, but that is based on resting HR, and I am skeptical of its accuracy. When I did a test on myself around 2/20, it came up with a number of 35 which, if true, would mean it was aerobically impossible for me to have done the workouts I did.
There are other submax and field tests you and do to estimate VO2 max. (ex: 12 min Cooper run test). Field tests are problematic because they require consistent effort and a peak performance that not everyone can do. Life Fitness treadmills have a 5 min walk test that is accessible to any user that is not bad--but it uses heart rate response to gauge effort so if your HRmax is less or higher than the "220-age" estimate, the VO2max score will be way off.
If you do have a Polar HRM with the "fit test" feature, you can take the test, and then refuse the score it gives you--then it gives you the option to enter your own score. With the V800, you can enter a VO2 max via the Polar Flow website w/out taking the test--not sure if that is available to everyone.
So in summary: HRM calorie counts are based on heart rate and VO2 max, not on the actual workload being performed. Exercise machines measure the actual workload and, if there are valid prediction equations for that type of machine, can use workload to estimate calories as reliably as an HRM. For maximum accuracy in calorie counts with an HRM, the HRM must be able to determine your aerobic fitness level, preferably VO2 max. If it cannot do that, I have no idea how they calorie counts can maintain any semblance of accuracy over time. Some Polar HRMs allow you to take a test to estimate VO2 max and/or input it manually. A more accurate VO2 number programmed into your HRM will result in a more accurate calorie estimate.
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Bump, because I spent a lot of time on this. And not every post can be "pet peeves at the gym".0
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bump to read later.0
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is there a TL/DR version?0
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Bump0
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liftsalltheweights wrote: »is there a TL/DR version?
TLDR; heart rate isn't a particularly accurate way to measure calories burned either. In some cases it can be less accurate than whatever equation the treadmill is using.
best to adjust your intake based on your actual body weight change.0 -
awesome post OP. thanks for getting into this.
but people would still rather pay $150 for the latest fad fitness device so it reports their incorrect numbers to them automagically!
I use heart rate monitors to measure my fatigue and effort level on a given day. They are a training tool (a very useful one I might add), they are not a dieting tool.0 -
liftsalltheweights wrote: »is there a TL/DR version?
I've written the TL/DR version in various comments about 100 times before, but the essence is this: If your HRM does not have a way to reassess your fitness level and/or allow you to enter in your VO2max, it will become progressively less accurate over time. It might also cause your brain to shrink and make you susceptible to marketing gibberish like "muscle confusion".0 -
The key is looking at my average HR -- it was the same for each workout. Since the Polar only monitors HR, it assumed I was working at the same level, only for fewer minutes. But, based on what I was able to accomplish, my performance clearly improved.
<snip>
They have their own margin of error, but if my treadmill says I burned 15 cal/min on one workout (2/5) and 18.5 cal/min (2/24) on another, that represents a substantial increase in both aerobic work and calories burned, even if those actual numbers are not 100% accurate.
Yet that performance increase did not show up in my HRM numbers. Why?
HRM calorie counts are based on the fact that, during aerobic exercise, there is a consistent relationship between heart rate (HR) and oxygen uptake (VO2). If intensity and VO2 go up, so does heart rate. If they go down, HR goes down as well. (You can clearly see that in the HR graphs for my workouts, since they were interval-type workouts alternating higher effort and lower effort).
Just taking aside this little part, and maybe I am not understanding you correctly, isn't that how it's supposed to work?
-HRM measures your HR and uses some age-based calculation (and your weight) to determine calories. (My Garmin includes some extra info for speed/distance and elevation as well I believe, but is mostly based on my HR)
-Treadmill uses just your weight, and the distance you covered and the time you covered it.
So of course the treadmill would say you burned more calories when you ran faster on two same-distance workouts. But if your heart rate was the same, because your fitness was improving, why would you expect the HRM to report higher calories? It shouldn't. Your body has adapted to the workouts you were doing before. You've improved, but you're now burning fewer calories at the same level of effort you were before.
Again, sorry maybe I am not understanding. I track my average heart rates over runs. As I get better I expect them to either get lower or stay the same. If I were to keep running the same workout over and over, eventually my average heart rate should get lower for that same distance and speed. But because we get more fit, we can run faster at the same heart rate. The treadmill doesn't know your level of effort. And just my personal opinion, but I don't like any calorie burn that gives us mortals more than 10 cals/minute. Obviously people have different experiences with that. But I know if I tried to eat back 12, 15 or even your hypothetical 18 cals/minute I would gain weight. I do think a very well trained athlete can burn more, maybe you are that athlete.
That's all I got for now, I'll try to read over more later for a 2nd time. I do like the numbers game, am a fan of the numbers myself.0 -
blues4miles wrote: »But if your heart rate was the same, because your fitness was improving, why would you expect the HRM to report higher calories? It shouldn't. Your body has adapted to the workouts you were doing before. You've improved, but you're now burning fewer calories at the same level of effort you were before
I think what you are trying to say is, you got fitter which means your body used the same # of calories to travel further and faster at the same HR.
But the only adaptation that this would be true for is technique - you are a more efficient runner (maybe less bouncing, less arm flailing, perfect stride length, etc). That's certainly one adaptation that makes you fitter, but I think OP is correct - technique improvements aside, running faster takes more oxygen. As you get fitter your oxygen utilization (VO2) improves. Your heart gets physically bigger, pumping more blood per heartbeat (that's why you have a lower/same heartbeat at a faster pace). So you are using more oxygen, and thus more calories, at the same heart rate as before.
Also, where did this magical "10 cal/min" ceiling number come from? I have seen that figure floating around, is there some kind of study that came up with it?
Numerous calculations for varying sources put me at a considerably higher number than this for many workouts. Usually 12-15.0 -
Another one to bookmark Azdak. Thanks.0
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blues4miles wrote: »The key is looking at my average HR -- it was the same for each workout. Since the Polar only monitors HR, it assumed I was working at the same level, only for fewer minutes. But, based on what I was able to accomplish, my performance clearly improved.
<snip>
They have their own margin of error, but if my treadmill says I burned 15 cal/min on one workout (2/5) and 18.5 cal/min (2/24) on another, that represents a substantial increase in both aerobic work and calories burned, even if those actual numbers are not 100% accurate.
Yet that performance increase did not show up in my HRM numbers. Why?
HRM calorie counts are based on the fact that, during aerobic exercise, there is a consistent relationship between heart rate (HR) and oxygen uptake (VO2). If intensity and VO2 go up, so does heart rate. If they go down, HR goes down as well. (You can clearly see that in the HR graphs for my workouts, since they were interval-type workouts alternating higher effort and lower effort).
Just taking aside this little part, and maybe I am not understanding you correctly, isn't that how it's supposed to work?
-HRM measures your HR and uses some age-based calculation (and your weight) to determine calories. (My Garmin includes some extra info for speed/distance and elevation as well I believe, but is mostly based on my HR)
-Treadmill uses just your weight, and the distance you covered and the time you covered it.
So of course the treadmill would say you burned more calories when you ran faster on two same-distance workouts. But if your heart rate was the same, because your fitness was improving, why would you expect the HRM to report higher calories? It shouldn't. Your body has adapted to the workouts you were doing before. You've improved, but you're now burning fewer calories at the same level of effort you were before.
Again, sorry maybe I am not understanding. I track my average heart rates over runs. As I get better I expect them to either get lower or stay the same. If I were to keep running the same workout over and over, eventually my average heart rate should get lower for that same distance and speed. But because we get more fit, we can run faster at the same heart rate. The treadmill doesn't know your level of effort. And just my personal opinion, but I don't like any calorie burn that gives us mortals more than 10 cals/minute. Obviously people have different experiences with that. But I know if I tried to eat back 12, 15 or even your hypothetical 18 cals/minute I would gain weight. I do think a very well trained athlete can burn more, maybe you are that athlete.
That's all I got for now, I'll try to read over more later for a 2nd time. I do like the numbers game, am a fan of the numbers myself.
Is this true? I'm a cyclist (sort of anyway), so it's easiest to use that as an example. If you cycle at 100 watts for an hour, your total energy output is 360kJ. Doesn't matter if you're Chris Froome, that's the energy required to turn the pedals for that long. The specific conversion between kj to calories does depend on effeciency and so on, but these adjustments are relatively small.
So if you do your 100 watt cycle at the start of training, your HR will be really high, after training for a year, it will be a lot lower, yet you have used very similar levels of energy. Your HR monitor will give a lot lower reading for the latter cycle. I think this what the OP is referring to.
Humans are bound by the laws of physics - we are converting chemical energy into kinetic energy, you're not going to use less energy/power just because you're fitter, you just find it easier.0 -
liftsalltheweights wrote: »is there a TL/DR version?
I've written the TL/DR version in various comments about 100 times before, but the essence is this: If your HRM does not have a way to reassess your fitness level and/or allow you to enter in your VO2max, it will become progressively less accurate over time. It might also cause your brain to shrink and make you susceptible to marketing gibberish like "muscle confusion".
As it becomes less accurate, do you think overestimating calories burned or underestimating is the result of the inaccuracy?
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Also, where did this magical "10 cal/min" ceiling number come from? I have seen that figure floating around, is there some kind of study that came up with it?
I read it so long ago I can no longer remember. I will poke around some on research sites and come back with what I find. I acknowledge I could of course be wrong so I will try to find some data either way...ConicalFern wrote: »blues4miles wrote: »The key is looking at my average HR -- it was the same for each workout. Since the Polar only monitors HR, it assumed I was working at the same level, only for fewer minutes. But, based on what I was able to accomplish, my performance clearly improved.
<snip>
They have their own margin of error, but if my treadmill says I burned 15 cal/min on one workout (2/5) and 18.5 cal/min (2/24) on another, that represents a substantial increase in both aerobic work and calories burned, even if those actual numbers are not 100% accurate.
Yet that performance increase did not show up in my HRM numbers. Why?
HRM calorie counts are based on the fact that, during aerobic exercise, there is a consistent relationship between heart rate (HR) and oxygen uptake (VO2). If intensity and VO2 go up, so does heart rate. If they go down, HR goes down as well. (You can clearly see that in the HR graphs for my workouts, since they were interval-type workouts alternating higher effort and lower effort).
Just taking aside this little part, and maybe I am not understanding you correctly, isn't that how it's supposed to work?
-HRM measures your HR and uses some age-based calculation (and your weight) to determine calories. (My Garmin includes some extra info for speed/distance and elevation as well I believe, but is mostly based on my HR)
-Treadmill uses just your weight, and the distance you covered and the time you covered it.
So of course the treadmill would say you burned more calories when you ran faster on two same-distance workouts. But if your heart rate was the same, because your fitness was improving, why would you expect the HRM to report higher calories? It shouldn't. Your body has adapted to the workouts you were doing before. You've improved, but you're now burning fewer calories at the same level of effort you were before.
Again, sorry maybe I am not understanding. I track my average heart rates over runs. As I get better I expect them to either get lower or stay the same. If I were to keep running the same workout over and over, eventually my average heart rate should get lower for that same distance and speed. But because we get more fit, we can run faster at the same heart rate. The treadmill doesn't know your level of effort. And just my personal opinion, but I don't like any calorie burn that gives us mortals more than 10 cals/minute. Obviously people have different experiences with that. But I know if I tried to eat back 12, 15 or even your hypothetical 18 cals/minute I would gain weight. I do think a very well trained athlete can burn more, maybe you are that athlete.
That's all I got for now, I'll try to read over more later for a 2nd time. I do like the numbers game, am a fan of the numbers myself.
Is this true? I'm a cyclist (sort of anyway), so it's easiest to use that as an example. If you cycle at 100 watts for an hour, your total energy output is 360kJ. Doesn't matter if you're Chris Froome, that's the energy required to turn the pedals for that long. The specific conversion between kj to calories does depend on effeciency and so on, but these adjustments are relatively small.
So if you do your 100 watt cycle at the start of training, your HR will be really high, after training for a year, it will be a lot lower, yet you have used very similar levels of energy. Your HR monitor will give a lot lower reading for the latter cycle. I think this what the OP is referring to.
Humans are bound by the laws of physics - we are converting chemical energy into kinetic energy, you're not going to use less energy/power just because you're fitter, you just find it easier.
But because you find it easier, it's not challenging you as much therefore you are burning fewer calories. My HRM reads higher on hotter days. Is a run in the heat more challenging than a run in cool weather? Would I expect if I ran at the same pace/distance in 90 degrees to burn more calories than in 60 degrees? Yes, why wouldn't I? But your argument I shouldn't. Just because I find the 60 degree weather 'easier' doesn't mean I shouldn't burn the same calories I burned on my agonizing 90 degree run.
Your argument though leads to what I think the real problem is. The OP thinks HRMs become less useful (for calories) as you get fitter. I think it's the opposite. I think they can be really inaccurate if you are unfit. The fitter you get, the closer to your optimal performance, the more accurate the calorie burn will be.
A couple days ago I ran (okay jogged/shuffled) 3.15 miles in ~48 minutes. My average heart rate was 156. I am an obese 30ish woman for reference. Garmin gave me 470 calories. I have been running around 3.1 miles for the last several weeks and Garmin will give me anywhere from 400 to 490 calories for those runs. Why the variability? Because some days I'm working harder than others. If you don't like that argument, that you shouldn't be using HRM calories. You should be using the formula (Runner's World has a good write-up on it: http://www.runnersworld.com/weight-loss/how-many-calories-are-you-really-burning). Gross: .75 x lbs x mile = total calories burned. But I wouldn't add that to my BMR because the time it took me to run those miles I would still have been using calories to keep all my organs going. So the real number NET is .63 x lbs x mile. That means I should get 377 calories EVERY TIME I run 3.1 miles. Whether I ran it in 15 minute-miles or 10 minute-miles. But I'm betting these formulas would give you guys much lower numbers than your HRM is giving you so that's why you don't like them.
So you guys are saying you think the HRM is accurate at the beginning but then becomes less accurate over time because you don't like that effort/challenge affects your calorie burn. So if that's what you really think, I'm saying the REAL thing that's happening is the HRM starts out wildly inaccurate and overestimating your burns and only becomes more accurate over time once it lowers and approaches the formula. 0 -
Meh. I've been using a HRM for years now, I log the calories, eat them back, and I lost a bunch of weight and I've been maintaining for two years.
Your calorie counts are very high. A 24 min 5K run for me barely burns 400 cals for me. Did you set that thing properly?
Max 165 HR is terrible, BTW. Run faster.0 -
blues4miles wrote: »
But because you find it easier, it's not challenging you as much therefore you are burning fewer calories.
his point is precisely the opposite: Just because something feels easier to you, does not mean it burns fewer calories.My HRM reads higher on hotter days. Is a run in the heat more challenging than a run in cool weather?
This is for a completely different reason. On hot days your heart needs to pump additional blood to your skin to allow you to cool yourself. Your heart can only pump so much blood per beat, and you are running at the same effort level. So that extra blood that needs to go to the skin increases demand on the heart and your HR increases. It has nothing to do with perceieved effort or calories burned.
She is not saying that. She is saying that as your fitness CHANGES (whether it is improving or getting worse) the calorie burn from heart rate must be calibrated as you go along.The OP thinks HRMs become less useful (for calories) as you get fitter. I think it's the opposite.
It has nothing to do with optimal performance. The calorie burn equations used by HRMs assume that heart rate correlates to VO2max, but your VO2 max is changing over time.I think they can be really inaccurate if you are unfit. The fitter you get, the closer to your optimal performance, the more accurate the calorie burn will be.
Back to point number 1, your perceived level of effort does not correlate to total calorie burn.Why the variability? Because some days I'm working harder than others. If you don't like that argument, that you shouldn't be using HRM calories.
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liftsalltheweights wrote: »is there a TL/DR version?
I've written the TL/DR version in various comments about 100 times before, but the essence is this: If your HRM does not have a way to reassess your fitness level and/or allow you to enter in your VO2max, it will become progressively less accurate over time. It might also cause your brain to shrink and make you susceptible to marketing gibberish like "muscle confusion".
As it becomes less accurate, do you think overestimating calories burned or underestimating is the result of the inaccuracy?
Underestimating.0 -
+1
Resting heart rate and recovery time are measures of fitness. Max HR is not.
Fortunately, cause I'd be on the brink of death if it were
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blues4miles wrote: »The key is looking at my average HR -- it was the same for each workout. Since the Polar only monitors HR, it assumed I was working at the same level, only for fewer minutes. But, based on what I was able to accomplish, my performance clearly improved.
<snip>
They have their own margin of error, but if my treadmill says I burned 15 cal/min on one workout (2/5) and 18.5 cal/min (2/24) on another, that represents a substantial increase in both aerobic work and calories burned, even if those actual numbers are not 100% accurate.
Yet that performance increase did not show up in my HRM numbers. Why?
HRM calorie counts are based on the fact that, during aerobic exercise, there is a consistent relationship between heart rate (HR) and oxygen uptake (VO2). If intensity and VO2 go up, so does heart rate. If they go down, HR goes down as well. (You can clearly see that in the HR graphs for my workouts, since they were interval-type workouts alternating higher effort and lower effort).
Just taking aside this little part, and maybe I am not understanding you correctly, isn't that how it's supposed to work?
-HRM measures your HR and uses some age-based calculation (and your weight) to determine calories. (My Garmin includes some extra info for speed/distance and elevation as well I believe, but is mostly based on my HR)
-Treadmill uses just your weight, and the distance you covered and the time you covered it.
So of course the treadmill would say you burned more calories when you ran faster on two same-distance workouts. But if your heart rate was the same, because your fitness was improving, why would you expect the HRM to report higher calories? It shouldn't. Your body has adapted to the workouts you were doing before. You've improved, but you're now burning fewer calories at the same level of effort you were before.
Again, sorry maybe I am not understanding. I track my average heart rates over runs. As I get better I expect them to either get lower or stay the same. If I were to keep running the same workout over and over, eventually my average heart rate should get lower for that same distance and speed. But because we get more fit, we can run faster at the same heart rate. The treadmill doesn't know your level of effort. And just my personal opinion, but I don't like any calorie burn that gives us mortals more than 10 cals/minute. Obviously people have different experiences with that. But I know if I tried to eat back 12, 15 or even your hypothetical 18 cals/minute I would gain weight. I do think a very well trained athlete can burn more, maybe you are that athlete.
That's all I got for now, I'll try to read over more later for a 2nd time. I do like the numbers game, am a fan of the numbers myself.
A 160 lb person running a 10min mile is burning about 10 cals per minute. It's not an uncommon feat, and certainly achievable by us mortals.
I'm lighter (120 lbs), so I'd need to run a 7:33min mile to do the same. I'm not quite there for a single mile (7:45), but almost. I concentrate on distance and not speed, though I've done a speed test in the last month.0 -
blues4miles wrote: »The key is looking at my average HR -- it was the same for each workout. Since the Polar only monitors HR, it assumed I was working at the same level, only for fewer minutes. But, based on what I was able to accomplish, my performance clearly improved.
<snip>
They have their own margin of error, but if my treadmill says I burned 15 cal/min on one workout (2/5) and 18.5 cal/min (2/24) on another, that represents a substantial increase in both aerobic work and calories burned, even if those actual numbers are not 100% accurate.
Yet that performance increase did not show up in my HRM numbers. Why?
HRM calorie counts are based on the fact that, during aerobic exercise, there is a consistent relationship between heart rate (HR) and oxygen uptake (VO2). If intensity and VO2 go up, so does heart rate. If they go down, HR goes down as well. (You can clearly see that in the HR graphs for my workouts, since they were interval-type workouts alternating higher effort and lower effort).
Just taking aside this little part, and maybe I am not understanding you correctly, isn't that how it's supposed to work?
-HRM measures your HR and uses some age-based calculation (and your weight) to determine calories. (My Garmin includes some extra info for speed/distance and elevation as well I believe, but is mostly based on my HR)
-Treadmill uses just your weight, and the distance you covered and the time you covered it.
So of course the treadmill would say you burned more calories when you ran faster on two same-distance workouts. But if your heart rate was the same, because your fitness was improving, why would you expect the HRM to report higher calories? It shouldn't. Your body has adapted to the workouts you were doing before. You've improved, but you're now burning fewer calories at the same level of effort you were before.
Again, sorry maybe I am not understanding. I track my average heart rates over runs. As I get better I expect them to either get lower or stay the same. If I were to keep running the same workout over and over, eventually my average heart rate should get lower for that same distance and speed. But because we get more fit, we can run faster at the same heart rate. The treadmill doesn't know your level of effort. And just my personal opinion, but I don't like any calorie burn that gives us mortals more than 10 cals/minute. Obviously people have different experiences with that. But I know if I tried to eat back 12, 15 or even your hypothetical 18 cals/minute I would gain weight. I do think a very well trained athlete can burn more, maybe you are that athlete.
That's all I got for now, I'll try to read over more later for a 2nd time. I do like the numbers game, am a fan of the numbers myself.
This isn't criticism, but your point about "efficiency" is exactly wrong. A lot of people--including people with fitness certifications--think the same thing. It's one of the reasons I write these posts--to correct that idea. The spread of HRMs has introduced this fallacy into the mainstream and it is difficult to correct.
To understand, you have to absorb the concept that the oxygen cost/calorie burn of an aerobic activity is built into the workload of the activity--speed, incline, watts, etc--NOT the heart rate. Heart rate is just a speedometer. I could give you a drug that raised your heart rate to 75% of maximum while you were sitting in a chair, but you won't not burn more calories, because you weren't doing any work.
So, for example, running 6 mph has an energy cost--about 10 METs. That's the same for everyone. You multiply 10 METs x your wt in kg and that's your calories/hour burn when you run 6 mph. Some who weighs 60kg will burn 600 cals/hr, an 80kg person will burn 800, and so on.
At the start of training, that 10 MET workload might represent 80% of your maximum oxygen uptake. So, when you run 6 mph and wear your HRM, the exercise HR will be 80% of your maximum heart rate (keeping it simple).
The whole point of training, however, is to INCREASE our aerobic maximum. So let's say you increase your max oxygen uptake 10%. Now, when you run at 6.0 mph, that workload of 10 METs only represents 75% of your aerobic max instead of 80%. Since your maximum heart rate has not changed, the exercise heart rate is now 75% of maximum, which will be lower.
Even though the heart rate is lower, the calorie burn is still the same (unless you lost weight). That's because the oxygen cost of 10 METs hasn't changed. It's just that now, 10 METs is a lower percentage of your aerobic maximum.
However, unless you can change it, the HRM doesn't know your maximum aerobic level has changed. HRMs can't measure the actual workload--they have to guess what you are doing based on the heart rate response. So the HRM assumes you are working at a lower workload and estimates fewer calories.
That has nothing to do with "efficiency". It's because your max fitness level has increased so that the same workload and same calorie burn requires less effort.
If you have a HRM that allows for manual input of VO2max and you change that number and increase it by 10%, your calorie burn will INCREASE for any given heart rate level. That's because you reset the scale.
Hope this helps a little. I understand that if one doesn't know the underlying physiology, it seems counterintuitive and the numbers on the HRM seem so tangible and "real" they're hard to ignore.0
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