Same Heart Rate = Same Calorie Burn?

Edit: To clarify, I am talking about the heart rate of the same person, during the same day (same level of physical fitness for activities) for different STEADY STATE CARDIO activities. I know it varies from person to person because we all will have different VO2max and oxygen usage. I know it may also vary in the same person from month to month as you get more fit.

My primary question is whether you are burning the same calories at the same heart rate regardless of the activity as long as it is a continuous cardio type activity. For example, if my heart rate tends to stay about 125 on the elliptical and also 125 when cycling, am I definitely burning the same amount of calories? Taking it one step further....when I crank up the resistance and/or incline but end up going slower and therefore have a similar heart rate, am I burning the same amount? I am very interested in the answers because I have issues with plantar fasciitis and my joints and have found that less incline and biking causes less pain. If I can be confident that I'm burning a similar amount using these alternatives (assuming a similar heart rate means a similar burn rate), I'll feel better about not cranking up the incline or feeling like I have to be doing a harder activity. I know according to the actual equipment readings, it will usually always assume more incline and more resistance creates a higher burn, but I suspect that is only true if you maintain the same speed and intensity, which I tend not to do.

The idea that the calorie burn seems similar based on the intensity I use which keeps me at a similar heart rate is what I have been noticing in my own calorie burns. I currently am using a Bodybugg by Bodymedia (does not measure heart rate but instead uses heat flux and/or motion to determine burn) to help track my calories burned during activity. It seems like I burn a very similar amount of calories while on the elliptical or cycling (the kind with a nice chair to sit in where you constantly are holding the heart rate monitor bars on either side of your hips). I generally do half the workout with the Bodybugg on my arm and half with it on my calf since I have read that it can underestimate on the arm for activities that predominantly are using the lower body. On the elliptical, I tested 10m on the arm and calf at an incline/resistance of 8 and then 6. For the incline/resistance of 8, I got a reading of 70 calories on my arm and 87 on my calf (both over 10m intervals). For the incline/resistance of 6, I got a reading of 71 calories on my arm and 87 on my calf. Basically, it was the same. Now, on the cycling, it got more interesting. For 10m on my arm, it showed only 13 steps (not surprising since I'm holding the heart rate monitor bars, but interesting because it implies that during this time the Bodybugg derived calorie burn primarily from heat flux due to having little motion data) and a calorie burn of 55. On my calf, cycling (still 10m) burned 108 calories while showing 681 steps (meaning the Bodybugg was likely now deriving a larger part of the burn equation from motion).

So, it appears that the overall calorie burn on the elliptical was 157-158 over 20m while it was 163 while cycling for the same time. Basically, this implies the burn is very similar. My heart rate also remained very similar generally staying between 120-130 for both. However, I am a bit concerned that there is a much bigger difference in burn on arm vs. calf for cycling vs. elliptical. For the elliptical it was 70/87 (arms are moving with elliptical) while it was 55/108 for cycling. I am curious if there may be an overestimate in play for the time the Bodybugg is on my calf while cycling. However, since my heart rate stays about the same between the activities, then that probably means my BB is correct and the difference is only down to the amount of arm movement difference between the elliptical and cycling. Additionally, during cycling, do you think there can be more heat coming from your legs than your arms since you are only using your lower body or is heat (calories burned) during activity supposed to be evenly dispersed across your body regardless of which parts are moving?

What are your thoughts?
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Replies

  • ladyoflucky13
    ladyoflucky13 Posts: 41 Member
    Also, I wanted to add that I realize the Bodybugg is not necessarily completely accurate. I am not so much asking about the exact accuracy of the number of calories burned so much as the relation between the calories burned for different activities (which I believe may be strongly correlated by heart rate, but that is what I'm looking for confirmation about).
  • brianpperkins
    brianpperkins Posts: 6,124 Member
    No, you are not burning the same amount of calories performing different activities at the same heart rate.
  • ladyoflucky13
    ladyoflucky13 Posts: 41 Member
    No, you are not burning the same amount of calories performing different activities at the same heart rate.
    Can you please explain your reasoning as to why that is so?
  • brianpperkins
    brianpperkins Posts: 6,124 Member
    Science.


    Heart rate does not determine caloric burn. There are relationships between heart rate and burn for certain activities but they all have different muscle involvement resulting in different burns ... totally different formulae. Walking is biomechanically different from walking which are both different from cycling ... or swimming ... skipping ... boxing ... dancing ... etc.

    If the same heart rate meant the same burn then sex and scary movies would be great calorie burns.


    http://www.myfitnesspal.com/blog/Azdak/view/the-real-facts-about-hrms-and-calories-what-you-need-to-know-before-purchasing-an-hrm-or-using-one-21472
  • DavPul
    DavPul Posts: 61,406 Member
    No, you are not burning the same amount of calories performing different activities at the same heart rate.
    Can you please explain your reasoning as to why that is so?

    because heart rate =/= calories burned rate. if that was the case Planet Fitness would have a Haunted House section instead of a Cardio section.
  • WalkingAlong
    WalkingAlong Posts: 4,926 Member
    I agree with Brian but I think for your purposes, you should do the exercise that doesn't hurt that you enjoy (or hate least) that gets your HR where you want it and the calories will be 'close enough'.

    I think you're splitting hairs expecting the Bugg to do much with skin temps and calf vs. arm and all. I know it says it does but I don't believe it. I've had one and I've had other trackers and I think the Bugg gets most of its data from an accelerometer like the rest of them do.

    Does it even say you can use it on your calf and expect good estimates? Or on a bike? I had mine long ago but I think then it expected you to have it on your arm and to manually log cycling.
  • ladyoflucky13
    ladyoflucky13 Posts: 41 Member
    No, you are not burning the same amount of calories performing different activities at the same heart rate.
    Can you please explain your reasoning as to why that is so?

    because heart rate =/= calories burned rate. if that was the case Planet Fitness would have a Haunted House section instead of a Cardio section.

    I am referring to heart rate solely during steady state cardio activities. I realize heart rate (and heart rate monitor readings) resulting from a scare or other non-cardio activity is not related to calorie burn. I was under the impression the way that heart rate monitors are able to estimate calorie burn during cardio is by taking a persons age, height, weight, estimated VO2max, etc. and guesstimating from there based on heart rate alone (which wouldn't take into account what kind of activity you are doing). Perhaps I am wrong in how a heart rate monitor is estimating the burn in the first place?
  • ladyoflucky13
    ladyoflucky13 Posts: 41 Member
    Science.


    Heart rate does not determine caloric burn. There are relationships between heart rate and burn for certain activities but they all have different muscle involvement resulting in different burns ... totally different formulae. Walking is biomechanically different from walking which are both different from cycling ... or swimming ... skipping ... boxing ... dancing ... etc.

    If the same heart rate meant the same burn then sex and scary movies would be great calorie burns.


    http://www.myfitnesspal.com/blog/Azdak/view/the-real-facts-about-hrms-and-calories-what-you-need-to-know-before-purchasing-an-hrm-or-using-one-21472

    I realize that heart rate is not a direct measure of calories burned. However, my understanding is that heart rate monitors are generally used to estimate calorie burns because it is difficult to directly measure oxygen consumption in anything other than a lab setting. I do understand there is a different muscle usage depending on activity and that is part of my wondering, but isn't the whole idea of why heart monitors work based on them being able to estimate oxygen usage from your heart rate once it already knows your gender, age, etc.?
  • BondBomb
    BondBomb Posts: 1,781 Member
    Actually I was wondering the same thing. When I am running or on the elliptical I am 'working' hard. Sweating my butt off, moving fast. However I don't have to exert nearly as much effort as I do on the stairclimber (stairmill). That thing is a killer, heart rate skyrockets. But again it feels like I am not doing the same amount of work.
    Please advise.
  • ladyoflucky13
    ladyoflucky13 Posts: 41 Member
    If the same heart rate meant the same burn then sex and scary movies would be great calorie burns.

    LOL....I thought the first activity did come with a bit of calorie burn... :laugh:
  • DavPul
    DavPul Posts: 61,406 Member
    Perhaps I am wrong in how a heart rate monitor is estimating the burn in the first place?

    well...you said "estimating" the burn, so you can't be totally wrong. it's an estimate based on an algorithm that is set based on information that you give it (weight, age, sex, VO2max, etc) and it uses that, along with your heart rate and the assumption that you are performing a steady state cardio activity to make it's best estimate on calorie burn rate. but it's not your "true" rate, just a best guess.

    different things could trigger different heart rates even tho they might burn the same amount of calories. and let's say you started walking hills when you were completely unfit. your HR might go thru the roof and you'll barely be able to breathe. Now you've run several 10ks and you're in much better shape. walking the same hill might barely make your HR go up and you'll breathe normally. the HRM will give you a lower estimate **even tho the exact same amount of energy (calories) are required to up that same hill (assuming you weigh the same).

    TL;DR it's just a guess. it's probably close enough to work with so don't spend a bunch of time worrying if you have your exact burn numbers. they really don't matter that much.
  • ladyoflucky13
    ladyoflucky13 Posts: 41 Member
    Does it even say you can use it on your calf and expect good estimates? Or on a bike? I had mine long ago but I think then it expected you to have it on your arm and to manually log cycling.

    I don't think there is an official ruling on using it on the calf. However, I have seen a lot of postings by cyclists who use it solely on their calf and claim it gives a much more accurate rate for times when your arms are in a fixed position. Most of the time, they were comparing their Bodybugg burn to a heart rate monitor, though. According to what people seem to be saying here, I am not sure how accurate heart rate monitors actually are, though, if the rate of calorie burn can vary depending on activity even though you have the same heart rate for the same person.
  • brianpperkins
    brianpperkins Posts: 6,124 Member
    No, you are not burning the same amount of calories performing different activities at the same heart rate.
    Can you please explain your reasoning as to why that is so?

    because heart rate =/= calories burned rate. if that was the case Planet Fitness would have a Haunted House section instead of a Cardio section.

    I am referring to heart rate solely during steady state cardio activities. I realize heart rate (and heart rate monitor readings) resulting from a scare or other non-cardio activity is not related to calorie burn. I was under the impression the way that heart rate monitors are able to estimate calorie burn during cardio is by taking a persons age, height, weight, estimated VO2max, etc. and guesstimating from there based on heart rate alone (which wouldn't take into account what kind of activity you are doing). Perhaps I am wrong in how a heart rate monitor is estimating the burn in the first place?

    Different ACTIVITIES burn different amounts. The way HRMs estimate caloric burn is based on hooking people up to direct calorimeters while monitoring their heart rates. From that data, different formulae emerged.
  • ladyoflucky13
    ladyoflucky13 Posts: 41 Member
    Perhaps I am wrong in how a heart rate monitor is estimating the burn in the first place?

    well...you said "estimating" the burn, so you can't be totally wrong. it's an estimate based on an algorithm that is set based on information that you give it (weight, age, sex, VO2max, etc) and it uses that, along with your heart rate and the assumption that you are performing a steady state cardio activity to make it's best estimate on calorie burn rate. but it's not your "true" rate, just a best guess.

    different things could trigger different heart rates even tho they might burn the same amount of calories. and let's say you started walking hills when you were completely unfit. your HR might go thru the roof and you'll barely be able to breathe. Now you've run several 10ks and you're in much better shape. walking the same hill might barely make your HR go up and you'll breathe normally. the HRM will give you a lower estimate **even tho the exact same amount of energy (calories) are required to up that same hill (assuming you weigh the same).

    TL;DR it's just a guess. it's probably close enough to work with so don't spend a bunch of time worrying if you have your exact burn numbers. they really don't matter that much.

    I realize over time it may change. I am basically asking if it is reasonably safe to assume for the same person and the same time period (same fitness level, weight, etc. therefore) if the calorie burn of something like cycling and elliptical should be similar if the heart rate is the same. It seems to be the consensus so far that this is not the case. It mystifies me a bit, though, because it seems that would make heart rate monitors quite inaccurate...and I thought they were supposed to be fairly accurate for steady state cardio.
  • brianpperkins
    brianpperkins Posts: 6,124 Member
    If the same heart rate meant the same burn then sex and scary movies would be great calorie burns.

    LOL....I thought the first activity did come with a bit of calorie burn... :laugh:

    Not really. On average it's well below 100 calories.
  • ladyoflucky13
    ladyoflucky13 Posts: 41 Member
    No, you are not burning the same amount of calories performing different activities at the same heart rate.
    Can you please explain your reasoning as to why that is so?

    because heart rate =/= calories burned rate. if that was the case Planet Fitness would have a Haunted House section instead of a Cardio section.

    I am referring to heart rate solely during steady state cardio activities. I realize heart rate (and heart rate monitor readings) resulting from a scare or other non-cardio activity is not related to calorie burn. I was under the impression the way that heart rate monitors are able to estimate calorie burn during cardio is by taking a persons age, height, weight, estimated VO2max, etc. and guesstimating from there based on heart rate alone (which wouldn't take into account what kind of activity you are doing). Perhaps I am wrong in how a heart rate monitor is estimating the burn in the first place?

    Different ACTIVITIES burn different amounts. The way HRMs estimate caloric burn is based on hooking people up to direct calorimeters while monitoring their heart rates. From that data, different formulae emerged.

    I do not currently have a heart rate monitor. Are you saying that heart rate monitors have different formula depending on what activity you are doing (of course steady state cardio) and therefore detect what activity you are doing and vary the formula based on that? I had no idea heart rate monitors were that advanced these days.
  • ladyoflucky13
    ladyoflucky13 Posts: 41 Member
    If the same heart rate meant the same burn then sex and scary movies would be great calorie burns.

    LOL....I thought the first activity did come with a bit of calorie burn... :laugh:

    Not really. On average it's well below 100 calories.

    So worth it. :blushing:
  • brianpperkins
    brianpperkins Posts: 6,124 Member
    If the same heart rate meant the same burn then sex and scary movies would be great calorie burns.

    LOL....I thought the first activity did come with a bit of calorie burn... :laugh:

    Not really. On average it's well below 100 calories.

    So worth it. :blushing:

    On average ... men burn more.
  • ladyoflucky13
    ladyoflucky13 Posts: 41 Member
    On average ... men burn more.

    Unfortunately, that's true for everything. Burning more and building muscle easier. I get jealous of my husband sometimes. :smile:
  • DavPul
    DavPul Posts: 61,406 Member
    Perhaps I am wrong in how a heart rate monitor is estimating the burn in the first place?

    well...you said "estimating" the burn, so you can't be totally wrong. it's an estimate based on an algorithm that is set based on information that you give it (weight, age, sex, VO2max, etc) and it uses that, along with your heart rate and the assumption that you are performing a steady state cardio activity to make it's best estimate on calorie burn rate. but it's not your "true" rate, just a best guess.

    different things could trigger different heart rates even tho they might burn the same amount of calories. and let's say you started walking hills when you were completely unfit. your HR might go thru the roof and you'll barely be able to breathe. Now you've run several 10ks and you're in much better shape. walking the same hill might barely make your HR go up and you'll breathe normally. the HRM will give you a lower estimate **even tho the exact same amount of energy (calories) are required to up that same hill (assuming you weigh the same).

    TL;DR it's just a guess. it's probably close enough to work with so don't spend a bunch of time worrying if you have your exact burn numbers. they really don't matter that much.

    I realize over time it may change. I am basically asking if it is reasonably safe to assume for the same person and the same time period (same fitness level, weight, etc. therefore) if the calorie burn of something like cycling and elliptical should be similar if the heart rate is the same. It seems to be the consensus so far that this is not the case. It mystifies me a bit, though, because it seems that would make heart rate monitors quite inaccurate...and I thought they were supposed to be fairly accurate for steady state cardio.

    but....you seem to be making the case that "inaccurate" means "not what you expected". it could very well be accurate and your expectations were skewed
  • ladyoflucky13
    ladyoflucky13 Posts: 41 Member
    Perhaps I am wrong in how a heart rate monitor is estimating the burn in the first place?

    well...you said "estimating" the burn, so you can't be totally wrong. it's an estimate based on an algorithm that is set based on information that you give it (weight, age, sex, VO2max, etc) and it uses that, along with your heart rate and the assumption that you are performing a steady state cardio activity to make it's best estimate on calorie burn rate. but it's not your "true" rate, just a best guess.

    different things could trigger different heart rates even tho they might burn the same amount of calories. and let's say you started walking hills when you were completely unfit. your HR might go thru the roof and you'll barely be able to breathe. Now you've run several 10ks and you're in much better shape. walking the same hill might barely make your HR go up and you'll breathe normally. the HRM will give you a lower estimate **even tho the exact same amount of energy (calories) are required to up that same hill (assuming you weigh the same).

    TL;DR it's just a guess. it's probably close enough to work with so don't spend a bunch of time worrying if you have your exact burn numbers. they really don't matter that much.

    I realize over time it may change. I am basically asking if it is reasonably safe to assume for the same person and the same time period (same fitness level, weight, etc. therefore) if the calorie burn of something like cycling and elliptical should be similar if the heart rate is the same. It seems to be the consensus so far that this is not the case. It mystifies me a bit, though, because it seems that would make heart rate monitors quite inaccurate...and I thought they were supposed to be fairly accurate for steady state cardio.

    but....you seem to be making the case that "inaccurate" means "not what you expected". it could very well be accurate and your expectations were skewed

    I think you may be partially misunderstanding what I'm after. I realize there is inaccuracy possible in both the equation the heart rate monitor uses and my Bodybugg. I am not asking for affirmation that the numbers I've shows are exactly right. If the bodybugg shows a burn of 150, I know it may in reality be 120 or 180. I realize that is the same for heart rate monitors. What I am talking about is under the same circumstances, same variables within the same equation, whether the burn would be approximately the same. I guess in part it depends on exactly what variables are being used in the HRM to estimate. I believe the equations generally use gender, age, weight, maybe height, VO2max (if you know it, otherwise an estimate based on the other given information), and heart rate. Knowing that, I would think that during a single given trip to the gym, where these variables don't change (I am not changing my gender, age, weight, VO2max, etc. over one session), is there some variable I am not seeing that would cause the calorie burn to change even though the heart rate is the same? The only thing in the equation that changes during a single session would seem to be heart rate based on a HRM equation. So, given that, why shouldn't 125 heart rate on elliptical be causing the same burn as a 125 heart rate on the bike? What part of the equation is being changed (or perhaps what part not able to be compensated for by the original HRM equation)? I know different muscles may be being used (and part of my original question was about how this changes the heat being put off which would relate to burn also), but I'd like something solid that explains why a different motion changes the equation either as estimated by a HRM or taking into account exactly what causes inaccuracies in the HRM in the first place.
  • ladyoflucky13
    ladyoflucky13 Posts: 41 Member
    OK....to try to make what I'm meaning clearer....here is the equation (perhaps inaccurate depending on the person, but still a model) of calories burned based on heart rate.


    Male: ((-55.0969 + (0.6309 x HR) + (0.1988 x W) + (0.2017 x A))/4.184) x 60 x T
    Female: ((-20.4022 + (0.4472 x HR) - (0.1263 x W) + (0.074 x A))/4.184) x 60 x T

    where

    HR = Heart rate (in beats/minute)
    W = Weight (in kilograms)
    A = Age (in years)
    T = Exercise duration time (in hours)

    So, when the gender, weight, age, and time (10m interval for example) stay the same, isn't heart rate the only variable left? Therefore, if the heart rate is the same (assuming steady state cardio), how can it be that it causes a different result? I understand this is a simplistic model that is guessing your calories burned based on an estimated VO2max and also an estimation of how many calories are being burned per % of maximum heart rate in comparison to that.
  • DavPul
    DavPul Posts: 61,406 Member
    during one activity you're supporting most of your own weight. on another you're mostly seated.

    either way, you're overthinking this. not many people screw up because they were a handful of calories off from their weekly gym estimates. that's a handful of hours in a 168 hour week. get the rest of the day right and don't spend much time fretting about <200 calories of workout burn
  • brianpperkins
    brianpperkins Posts: 6,124 Member
    Perhaps I am wrong in how a heart rate monitor is estimating the burn in the first place?

    well...you said "estimating" the burn, so you can't be totally wrong. it's an estimate based on an algorithm that is set based on information that you give it (weight, age, sex, VO2max, etc) and it uses that, along with your heart rate and the assumption that you are performing a steady state cardio activity to make it's best estimate on calorie burn rate. but it's not your "true" rate, just a best guess.

    different things could trigger different heart rates even tho they might burn the same amount of calories. and let's say you started walking hills when you were completely unfit. your HR might go thru the roof and you'll barely be able to breathe. Now you've run several 10ks and you're in much better shape. walking the same hill might barely make your HR go up and you'll breathe normally. the HRM will give you a lower estimate **even tho the exact same amount of energy (calories) are required to up that same hill (assuming you weigh the same).

    TL;DR it's just a guess. it's probably close enough to work with so don't spend a bunch of time worrying if you have your exact burn numbers. they really don't matter that much.

    I realize over time it may change. I am basically asking if it is reasonably safe to assume for the same person and the same time period (same fitness level, weight, etc. therefore) if the calorie burn of something like cycling and elliptical should be similar if the heart rate is the same. It seems to be the consensus so far that this is not the case. It mystifies me a bit, though, because it seems that would make heart rate monitors quite inaccurate...and I thought they were supposed to be fairly accurate for steady state cardio.

    but....you seem to be making the case that "inaccurate" means "not what you expected". it could very well be accurate and your expectations were skewed

    I think you may be partially misunderstanding what I'm after. I realize there is inaccuracy possible in both the equation the heart rate monitor uses and my Bodybugg. I am not asking for affirmation that the numbers I've shows are exactly right. If the bodybugg shows a burn of 150, I know it may in reality be 120 or 180. I realize that is the same for heart rate monitors. What I am talking about is under the same circumstances, same variables within the same equation, whether the burn would be approximately the same. I guess in part it depends on exactly what variables are being used in the HRM to estimate. I believe the equations generally use gender, age, weight, maybe height, VO2max (if you know it, otherwise an estimate based on the other given information), and heart rate. Knowing that, I would think that during a single given trip to the gym, where these variables don't change (I am not changing my gender, age, weight, VO2max, etc. over one session), is there some variable I am not seeing that would cause the calorie burn to change even though the heart rate is the same? The only thing in the equation that changes during a single session would seem to be heart rate based on a HRM equation. So, given that, why shouldn't 125 heart rate on elliptical be causing the same burn as a 125 heart rate on the bike? What part of the equation is being changed (or perhaps what part not able to be compensated for by the original HRM equation)? I know different muscles may be being used (and part of my original question was about how this changes the heat being put off which would relate to burn also), but I'd like something solid that explains why a different motion changes the equation either as estimated by a HRM or taking into account exactly what causes inaccuracies in the HRM in the first place.

    Because different muscles and motions require different energy amounts. Measure it in joules, watts produced, calories expended ... it doesn't matter ... the energy requirements differ between activities. Because of those differences, the equations used to calculate energy expenditure are different for each ... it isn't just the heart rate that varies but you don't see that since the full formula is buried in the background of the HRM or activity monitor.
  • brianpperkins
    brianpperkins Posts: 6,124 Member
    Walk for an hour at a fast enough pace to elevate your heart rate ... then run for an hour as slow as necessary to keep your heart rate at the same level as on your walk .... which burns more?
  • ladyoflucky13
    ladyoflucky13 Posts: 41 Member
    during one activity you're supporting most of your own weight. on another you're mostly seated.

    either way, you're overthinking this. not many people screw up because they were a handful of calories off from their weekly gym estimates. that's a handful of hours in a 168 hour week. get the rest of the day right and don't spend much time fretting about <200 calories of workout burn

    I realize the difference is not huge and it won't make a huge difference in the grand scheme. However, I like to understand the science of my body and how things work. I know equations are just models and not always accurate, but they should be relatively consistent in their inaccuracy for a given person and set variables. For me, this issue is more psychological with regard to seeing the same heart rate and trying to achieve the same burn since I have a tendency to push through the pain and cause more damage otherwise. This doesn't mean I want to believe something not true, though. I want to understand it properly.
  • ladyoflucky13
    ladyoflucky13 Posts: 41 Member
    Perhaps I am wrong in how a heart rate monitor is estimating the burn in the first place?

    well...you said "estimating" the burn, so you can't be totally wrong. it's an estimate based on an algorithm that is set based on information that you give it (weight, age, sex, VO2max, etc) and it uses that, along with your heart rate and the assumption that you are performing a steady state cardio activity to make it's best estimate on calorie burn rate. but it's not your "true" rate, just a best guess.

    different things could trigger different heart rates even tho they might burn the same amount of calories. and let's say you started walking hills when you were completely unfit. your HR might go thru the roof and you'll barely be able to breathe. Now you've run several 10ks and you're in much better shape. walking the same hill might barely make your HR go up and you'll breathe normally. the HRM will give you a lower estimate **even tho the exact same amount of energy (calories) are required to up that same hill (assuming you weigh the same).

    TL;DR it's just a guess. it's probably close enough to work with so don't spend a bunch of time worrying if you have your exact burn numbers. they really don't matter that much.

    I realize over time it may change. I am basically asking if it is reasonably safe to assume for the same person and the same time period (same fitness level, weight, etc. therefore) if the calorie burn of something like cycling and elliptical should be similar if the heart rate is the same. It seems to be the consensus so far that this is not the case. It mystifies me a bit, though, because it seems that would make heart rate monitors quite inaccurate...and I thought they were supposed to be fairly accurate for steady state cardio.

    but....you seem to be making the case that "inaccurate" means "not what you expected". it could very well be accurate and your expectations were skewed

    I think you may be partially misunderstanding what I'm after. I realize there is inaccuracy possible in both the equation the heart rate monitor uses and my Bodybugg. I am not asking for affirmation that the numbers I've shows are exactly right. If the bodybugg shows a burn of 150, I know it may in reality be 120 or 180. I realize that is the same for heart rate monitors. What I am talking about is under the same circumstances, same variables within the same equation, whether the burn would be approximately the same. I guess in part it depends on exactly what variables are being used in the HRM to estimate. I believe the equations generally use gender, age, weight, maybe height, VO2max (if you know it, otherwise an estimate based on the other given information), and heart rate. Knowing that, I would think that during a single given trip to the gym, where these variables don't change (I am not changing my gender, age, weight, VO2max, etc. over one session), is there some variable I am not seeing that would cause the calorie burn to change even though the heart rate is the same? The only thing in the equation that changes during a single session would seem to be heart rate based on a HRM equation. So, given that, why shouldn't 125 heart rate on elliptical be causing the same burn as a 125 heart rate on the bike? What part of the equation is being changed (or perhaps what part not able to be compensated for by the original HRM equation)? I know different muscles may be being used (and part of my original question was about how this changes the heat being put off which would relate to burn also), but I'd like something solid that explains why a different motion changes the equation either as estimated by a HRM or taking into account exactly what causes inaccuracies in the HRM in the first place.

    Because different muscles and motions require different energy amounts. Measure it in joules, watts produced, calories expended ... it doesn't matter ... the energy requirements differ between activities. Because of those differences, the equations used to calculate energy expenditure are different for each ... it isn't just the heart rate that varies but you don't see that since the full formula is buried in the background of the HRM or activity monitor.

    So, you are basically saying that if we were going by the simplistic HRM equation, it would probably be the same. It is the real life side of things that causes it to not be true? Is there any way of estimating how much these real life factors affect the equation? What is the percent error when using a HRM? Is it something like 10% or more like 30%?
  • ladyoflucky13
    ladyoflucky13 Posts: 41 Member
    Walk for an hour at a fast enough pace to elevate your heart rate ... then run for an hour as slow as necessary to keep your heart rate at the same level as on your walk .... which burns more?

    For me personally, I am pretty sure it would be impossible for a running heart rate to ever be as low as a walking heart rate...however, I also don't run because of how much stress it causes my joints and heel. Is it possible for a normal weight person to have a similar heart rate fast walking vs slow running?
  • DavPul
    DavPul Posts: 61,406 Member
    ..... For me, this issue is more psychological with regard to seeing the same heart rate and trying to achieve the same burn since I have a tendency to push through the pain and cause more damage otherwise.

    well, this is an entirely different problem and i would recommend that you address that as opposed to anything fitness related.
  • ladyoflucky13
    ladyoflucky13 Posts: 41 Member
    I appreciate the responses I am getting. Thank you for taking the time to post.