I think my HRM is trippin' bawwls

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  • W0zzie
    W0zzie Posts: 262 Member
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    @Jesse13 "My polar says "transmitter error at times" and the heart rate is all over the place.."

    If you interested I posted this up a few days back on what I found with mine - if the F40 is the wearlink strap, it might help you.

    http://www.myfitnesspal.com/topics/show/322302-is-your-polar-wearlink-strap-giving-you-grief?hl=wearlink+grief#posts-4297229
  • mowu
    mowu Posts: 245 Member
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    Makes sense..yeah... but this always makes me wanna question...whether the correlation between heart rate and calories burnt is really all that accurate..

    Healthy skepticism - I like it

    Of course the heart rate vs. calories burned correlation is just an estimate. It is a good estimate typically based on formulas derived from sound scientific models based on significant statistical data......but still just an estimate.

    It is however the best portable estimation you can get as an absolute measurement would require you to use calibrated precision equipment to measure the watts you put out, temperature and oxygen (and probably a bunch of other stuff......in a controlled enviroment)
  • Azdak
    Azdak Posts: 8,281 Member
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    Makes sense..yeah... but this always makes me wanna question...whether the correlation between heart rate and calories burnt is really all that accurate..

    It can be accurate enough, but only under certain conditions. That's the part that most people do not understand and that the HRM manufacturers gloss over (not saying anyone is wrong or unethical--that's just the way it is).

    The HR--calories burned relationship is most accurate only during steady-state aerobic exercise. Anything else, and you start to veer off from the "best fit" line of the equation, sometimes by a little, sometimes by a lot.

    And, most importantly, the correlation is only as accurate as your input data. The biggest confounding factor is the lack of an accurate maximum heart rate. The formula used to estimate maximum heart rate -- the one used by the HRM -- only applies to 60%-65% of the population--and it can be off by 20-30 beats/min for some people.

    Unfortunately, learning your true max HR is not that easy.

    The correlation between HR and calories burned is actually an estimate of an estimate. Actual calories burned is estimated in the lab by measuring oxygen uptake. Increased oxygen uptake = increased calories burned. The elevation of heart rate during steady-state aerobic exercise can be used to estimate increased oxygen uptake.

    The other confounding factor is that, under certain conditions or during certain activities, heart rate can increase WITHOUT an increase in oxygen uptake--or with a much smaller increase than during aerobic exercise. Under those conditions, the calorie counts on HRMs are way off. Those conditions include: thermal stress, cardiovascular drift, strength training, illness, anxiety, and exercises that involve a lot of upper-body work.
  • futurefitgirl88
    futurefitgirl88 Posts: 284
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    Azdak that was very educational! :) Thanks

    I could dwell on this for a long time so instead of focusing on how many calories I'm burning. I think I should focus on burning more!!!
  • HonestOmnivore
    HonestOmnivore Posts: 1,356 Member
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    I was "running" Wednesday and my HRM showed I was over 200bpm which couldn't have been true because I should have been hating the world out of breath and struggling big time - so I think the HRMs can get a little goofy at times. I have quotes around the word running because I'm just learning and run so slowly that walkers pass me!

    I use mine as a guide - to help me better understand my effort which as you say, can feel very disconnected from my heart rate! I tend to show a higher heart rate doing full body work at a lighter level than elliptical, legs only or running.

    Azdak - we do burn more calories at a higher heart rate? Or should we use the impression of effort as our guide? I thought it correlated to heart rate but that the actual calories burned was an educated guess by the HRMs...
  • Azdak
    Azdak Posts: 8,281 Member
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    I was "running" Wednesday and my HRM showed I was over 200bpm which couldn't have been true because I should have been hating the world out of breath and struggling big time - so I think the HRMs can get a little goofy at times. I have quotes around the word running because I'm just learning and run so slowly that walkers pass me!

    I use mine as a guide - to help me better understand my effort which as you say, can feel very disconnected from my heart rate! I tend to show a higher heart rate doing full body work at a lighter level than elliptical, legs only or running.

    Azdak - we do burn more calories at a higher heart rate? Or should we use the impression of effort as our guide? I thought it correlated to heart rate but that the actual calories burned was an educated guess by the HRMs...

    A sudden, exceptionally high heart rate reading, esp in the absence of any symptoms, is often due to an error with the HRM--contact issue w/the chest strap, electrical interference, or low battery.

    In answer to your calorie question: you burn more calories at a higher heart rate if it is accompanied by a higher oxygen uptake. If not, you don't.

    Here are some real world examples:

    You are running at a given speed, say 6.0 mph. You increase speed to 6.5 or you start up a hill, or you run into a 20 mph headwind and maintain your speed. HR will increase and so will calories. HRM is most accurate under these conditions.

    You are doing a set of leg presses. Before set, HR is 100. Afterwards, HR increases to 140. This, however, is a *pressure* mediated increase and does not increase oxygen uptake (much). Calorie burn increases only slightly, even though HR increases a lot.

    You do non-aerobic exercise in a hot room (e.g. bikram yoga). After an hour, the HRM says you burned 1000 calories. No. Because of thermal stress, HR goes way up, but oxygen uptake does not. The calorie burn is only equal to a mild stroll. (In this case, sweating and muscle fatigue are irrelevant).

    You run 3 miles outside on two consecutive days. The first day the temp is 70 degrees, the next day 90. You run at roughly the same effort. The HRM shows that on the second day you burned 20% more calories. No you didn't.

    You do a 60 min circuit training class that involves a lot of upper body work--kettle bell swings, over head presses, etc. Your HRM says your HR average was 85% of max HR. In this scenario, you did a mixture of "aerobic" type movements and resistance movements, plus the upper body movements. Even though HR averaged 85% of max HR, you likely burned 25%-40% fewer calories than you would have running continuously for 1 hr at the same average HR (assuming you could do that).

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