THIS is why HRMs have limited use for tracking calories

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  • 3dogsrunning
    3dogsrunning Posts: 27,167 Member
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    I haven't read all the replies yet, but this speaks to what I've been thinking today. I have plateaued on my weight loss, though I can see some change in how my clothes fit and such. I have a bioimpedence scale which measures BF and muscle mass percentages, and those numbers haven't really changed much either (I realize it may not be the most accurate measure of either statistic, but since I'm using the same method day-to-day, I figure I'm comparing apples to apples and would notice a change if there was one).

    I'm also aware that some of my issue is that I haven't been eating quite like I need to be, and I'm working on that.

    So as of today, I plan to enter my exercise calories (as per my HRM) into MFP on my cardio days and eat those back, but not on lifting days. In my head I will know that I did burn calories with my lifting, but how much would be a total guess. I don't know how this will turn out, but time will tell.

    That's not a bad plan.

    I give myself 200 extra calories a day on lifting days (when I was lifting, I'm doing crossfit now so it's a little different). It's pretty much what MFP gave me. It's a few extra calories to fuel my body, I know I burned a little bit for sure and even if I only burned 100, the other 100 won't make of break me.
    I'm not saying you have to do that, or use 200 exactly, but its an idea.
  • jaygreen55
    jaygreen55 Posts: 315 Member
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    Question for Adzak

    How accurate is the fitness level assessments of the more advanced polar HRMs? When I perform fitness tests with my polar F11 it gives me a VO2 max rating ranging from 49-52 while my new FT 60 rates me from 44-47. The F11 allows you to enter your resting heart as well as your maximum heart rate while the FT60 allows entry for max heart rate only. Can the FT60 calculate HR reserve without knowing your resting heart rate.?

    I have experimented with wearing both HRMs simultaneously. Using the VO2 max chosen by the monitors the F11 gives me a much higher calories burned (as you would expect) but if I manually set the VO2max the same (either lower or higher) the claories ae very close (+- 5%) The question is which measurement of VO2 max if either is more accurate
  • heybales
    heybales Posts: 18,842 Member
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    This is basically what they use, perhaps slightly tweaked. So basically BMI based, with additional info of HRmax and resting HR, and your assessment of fitness level.

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

    Study against an actual HRM for women.

    http://www.ncbi.nlm.nih.gov/pubmed/21178923

    Study against an actual HRM for men.

    http://www.asep.org/asep/asep/JEPonlineOctober2011Esco.pdf

    Those will help show where it starts to lose it for estimating decently - higher ends are worse. But likely you are reached those higher levels by specific training, gained by having a VO2max test, therefore you have a stat to manually enter.

    My RS300X is low by about 8 from tested level.

    Also, even if you can't enter in resting HR, that's what it is reading, hence Polar's FAQ says to do it in the morning after a rest day, to get good reading of resting HR.

    Also, you should do it after a weight change of perhaps 5 lbs, because even if your fitness level stayed the same (VO2 ml / liter), the mere act of weighing less means your VO2 max mL/kg goes up.
  • MrsDanner78
    MrsDanner78 Posts: 107
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    bump
  • Azdak
    Azdak Posts: 8,281 Member
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    Question for Adzak

    How accurate is the fitness level assessments of the more advanced polar HRMs? When I perform fitness tests with my polar F11 it gives me a VO2 max rating ranging from 49-52 while my new FT 60 rates me from 44-47. The F11 allows you to enter your resting heart as well as your maximum heart rate while the FT60 allows entry for max heart rate only. Can the FT60 calculate HR reserve without knowing your resting heart rate.?

    I have experimented with wearing both HRMs simultaneously. Using the VO2 max chosen by the monitors the F11 gives me a much higher calories burned (as you would expect) but if I manually set the VO2max the same (either lower or higher) the claories ae very close (+- 5%) The question is which measurement of VO2 max if either is more accurate


    Sorry, I had to go to work for awhile. I have tried and tried to get a six-figure, full-time gig just answering questions on MFP, but so far, no joy. :ohwell:

    I am not a big fan of fitness assessments based on resting heart rate. The fact is that the correlation between resting heart rate and fitness level is pretty weak. And the longer you exercise, the more likely your resting heart rate will be low, no matter what. When I was at my heaviest and least fit, by resting HR was still in the mid-50s. My Polar still told me I was the fittest of them all.

    I'm not sure what the best choice is. Some submax tests do reasonably well, but only if your HR max matches the 220-age estimate. If you are way above that then they underestimate VO2max, sometimes by a lot. If you know how to push yourself at a performance level, something like the Cooper 12-min run test might have some value, mostly because it is performance-based, not heart rate based.

    It's not surprising you would get different readings between the F11 and FT60--the consensus on the Polar forums is that there was a noticeable change in software when the models changed.

    I have an FT60, but to be honest I have never really paid much attention to any of the training features--I just wanted something that would allow me to enter VO2max manually (why I don't know since I don't pay attention to the calories--but I alway buy more technology than I need). I believe the FT60 focuses on Polar features such as the fitness test and the OwnIndex. IIRC, the FT60 does some type of detailed sensing of HR response to exertion that indicates a % of maximum, or particular "zone" without resorting to the standard Karvonen formula of HR reserve. To be honest, I just manually set my own zones and didn't really let Polar do anything.
  • anemoneprose
    anemoneprose Posts: 1,805 Member
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    Bump for later (& thank you, Azdak!).
  • pushyourself14
    pushyourself14 Posts: 275 Member
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    Very interesting! Thank you for posting :)
  • afreelandgti
    afreelandgti Posts: 73
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    Excellent info very much appreciated.
  • MelodyandBarbells
    MelodyandBarbells Posts: 7,725 Member
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    Yikes- so what should I use to calculate workouts like BodyPump?

    For something like Body Pump, you could probably multiply your body wt in kg by 5 to get calories per hour. That would likely be as accurate as anything.

    LOL. The FT4 has me right around that range for BodyPump. Often less! It's like ever since I had one week off and did 5 BodyPump classes in one week, I came back and my burn was 100 - 150 calories less than it used to be. I guess "strength training" really does mean heavy *kitten* 300lb weights, which I don't do, so maybe the FT4 will suit just fine after all, other than maybe adjusting up max hr.

    PS: What does LT mean?
  • MelodyandBarbells
    MelodyandBarbells Posts: 7,725 Member
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    Definitely not lifting weights. First of all because I can't--the only gym I have access to is a military base gym and if a "fatty" comes anywhere near the weight room they get run off pretty quickly. Those meatheads would rather I die than try to better myself. Doesn't matter if I plead my case to the actual service members working...they feel the same way.
    There's no way any of that happened.

    ETA...forget it. Not worth arguing over anymore. I don't know why I feel like I have to prove myself to a bunch of strangers behind computer screens anyway. Fact is you aren't at this base, and you have no idea what goes on here...
    Fact is I served in the Air Force and am familiar with the UCMJ and other relevant regulations. Nobody would be stupid enough to pick fights with random strangers on base (and especially commit assault/battery in a public place) because they don't know either your rank or whose wife/daughter/niece/etc you might be. And also you could ruin their lives by walking in with a camera and recording their behavior to show to their superiors.

    It didn't happen. Find a better excuse and stop blaming it on people who volunteered to serve.

    And, of course, no one in the military ever gets court martialed because they all know their behavior is being observed and should be above reproach at all times. The fact that people know better is not proof that they in fact do better, at all times. I think you're the one making excuses if you would deny the potential douche baggery of people you do not know on a blanket basis just because they serve. They are flawed humans, same as anyone else, not super heroes.
  • Squidgeypaws007
    Squidgeypaws007 Posts: 1,012 Member
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    Interesting topic - I'm just in the process of re-evaluating what I'm eating and how many calories I'm consuming with regards to my exercise, so this has come at just the right time. Thanks!
  • cyclebummer
    cyclebummer Posts: 29
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    Good discussion. The faster you breath when exercising, the faster your heart beats, the more cals burned. Cals burned vs exercise has to be adjusted, with experience, to match YOUR physiologic response. You can't rely on the generalized stats generated by MFP. I've adjusted my baseline cal burn as well as the cal burn for various forms of exercise to more realistic numbers for ME. Downward by about 15%.
  • heybales
    heybales Posts: 18,842 Member
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    LOL. The FT4 has me right around that range for BodyPump. Often less! It's like ever since I had one week off and did 5 BodyPump classes in one week, I came back and my burn was 100 - 150 calories less than it used to be. I guess "strength training" really does mean heavy *kitten* 300lb weights, which I don't do, so maybe the FT4 will suit just fine after all, other than maybe adjusting up max hr.

    PS: What does LT mean?

    LT - Lactate Threshold

    That point where the carbs you are burning has become anaerobic , producing just enough lactate acid you are now not using it or clearing it out of the muscles as fast as it's building up.
    Workout slightly above LT, it may take a bit but you'll get that burning that eventually prevents you from continuing, at least at that pace.
    Workout well above LT, where lifting and sprints would usually take you if muscles are fresh enough, and the burn will be pretty fast and you'll likely have to stop that pace very quickly, and the recovery level is much less.

    For sprints and cardio right above the line, you can push it up, as the body deals better with using existing lactate acid so it doesn't build up as fast, and pushing off the point where it become debilitating and you must stop.

    There is an average assumed LT based on average assumed HRmax. And there is an average assumed relationship between VO2max and HRmax, which means there is an average assumed VO2 level for the LT.

    So a line from usually 90 bpm to your LT level is a straight line function for a relationship between calories burned and HR.
    But you notice all the assumed averages in there - hence the reason it can be very off for many.
    Go over the LT in cardio and the calorie burn line continues. Go over the LT in anaerobic non-cardio exercise and it has no relationship at all.
  • heybales
    heybales Posts: 18,842 Member
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    Good discussion. The faster you breath when exercising, the faster your heart beats, the more cals burned. Cals burned vs exercise has to be adjusted, with experience, to match YOUR physiologic response. You can't rely on the generalized stats generated by MFP. I've adjusted my baseline cal burn as well as the cal burn for various forms of exercise to more realistic numbers for ME. Downward by about 15%.

    Kind of.

    But getting in to a hyper-ventilation mode can have you breathing faster without corresponding increase in HR - and therefore calories burned did not go up.
    Conversely, you can have stress or heat elevated HR for reason of cooling effect without increase in breathing - and therefore calories burned did not go up.

    But in general that is a good method, it's what Garmin HRM's using FirstBeat algorithms attempt to do, watch the breathing in relation to the HR.
    If the HR shoots up fast and breathing did not - that's anaerobic, ignore calculating calories for that spike. Observed that.
    If HR is at certain level but breathing seems less - that's heat elevated HR and calculate slightly lower level. Observed that.
    I've fooled it too though, for a lap purposely breathing at faster rate than needed

    Adzak didn't even get in to the potential inaccuracies for what the HRM is only really decently valid with that can cause inaccuracies there too.

    So many have been disappointed here with the lifting info, shudder to think how they'll react to what can happen during their aerobic exercise.
  • beachgirl172723
    beachgirl172723 Posts: 151 Member
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    bump for later
  • no1dragn
    no1dragn Posts: 26 Member
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    Why not just use the 'average heart rate' and calculate the calories yourself? I find that when I do that, my calculated calories are quite a bit lower than what the HRM calculates.

    The formula that I use is (note, for women):

    Calories Burned = [(Age x 0.074) -- (Weight x 0.05741) + (Heart Rate x 0.4472) -- 20.4022] x Time / 4.184.

    For men:
    Calories Burned = [(Age x 0.2017) + (Weight x 0.09036) + (Heart Rate x 0.6309) -- 55.0969] x Time / 4.184.
  • Carfoodel
    Carfoodel Posts: 481 Member
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    Why not just use the 'average heart rate' and calculate the calories yourself? I find that when I do that, my calculated calories are quite a bit lower than what the HRM calculates.

    The formula that I use is (note, for women):

    Calories Burned = [(Age x 0.074) -- (Weight x 0.05741) + (Heart Rate x 0.4472) -- 20.4022] x Time / 4.184.

    For men:
    Calories Burned = [(Age x 0.2017) + (Weight x 0.09036) + (Heart Rate x 0.6309) -- 55.0969] x Time / 4.184.

    I just used the formula above and the calories are actually a bit higher using it than my HRM is giving (by about 100-150 cals on some sessions) I used it on different training logs from hiking, strength/bootcamp type workout and straight cardio.

    hmm I guess I am still getting healthy regardless, just want to get better about fuelling my workouts and it would be really nice if the scales would budge a bit lol. - which formula is that?
  • Azdak
    Azdak Posts: 8,281 Member
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    Why not just use the 'average heart rate' and calculate the calories yourself? I find that when I do that, my calculated calories are quite a bit lower than what the HRM calculates.

    The formula that I use is (note, for women):

    Calories Burned = [(Age x 0.074) -- (Weight x 0.05741) + (Heart Rate x 0.4472) -- 20.4022] x Time / 4.184.

    For men:
    Calories Burned = [(Age x 0.2017) + (Weight x 0.09036) + (Heart Rate x 0.6309) -- 55.0969] x Time / 4.184.

    Those equations use the exact same assumptions as those used in HRMs and are subject to the exact same limitations and errors.
  • Carfoodel
    Carfoodel Posts: 481 Member
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    ha- of course -thanks Azdak, you would think someone would come up with something that would be able to give you a ballpark sort of estimate.

    so, basically solid state kinda accurate (ish) ignore any cals reported from strength sessions and take it with a pinch of salt for any other cardio. I still love my hrm for motivation on comparison of sessions and tracking my progress, so it works for me.

    must admit I find it annoying that it keeps telling me each week that I need to take a recovery week but I am training for events so have to hit it hard. I haven't even used the strength training programme built in yet (which may be useless anyway by the indications here lol)
  • Azdak
    Azdak Posts: 8,281 Member
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    ha- of course -thanks Azdak, you would think someone would come up with something that would be able to give you a ballpark sort of estimate.

    so, basically solid state kinda accurate (ish) ignore any cals reported from strength sessions and take it with a pinch of salt for any other cardio. I still love my hrm for motivation on comparison of sessions and tracking my progress, so it works for me.

    must admit I find it annoying that it keeps telling me each week that I need to take a recovery week but I am training for events so have to hit it hard. I haven't even used the strength training programme built in yet (which may be useless anyway by the indications here lol)

    Keep in mind that the strength training program(me) as I understand it, uses heart rate analysis to recommend changes in training routine. That's different than trying to estimate calories.

    I don't want to make it sound like I am trashing HRMs (or Polar) indiscriminately. I think they overstate the accuracy of a number of their features (and downplay the individual variability that affects them), but they have been doing research on heart rate and analyzing heart rate response to exercise for many years. I have never tried any of their training features, so I can't comment on how useful they are, but they do make quality, reliable training products.

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