HRM strap accuracy for calculating calories burned

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scottrey
scottrey Posts: 18 Member
in Fitness and Exercise
Hi all. I have a HRM strap from Polar that I connect to my phone via bluetooth. I used Edomondo to record a short test session on my bike trainer, and I'm not sure if I trust the accuracy of the report it gave me for calories burned. I will preface the below stats with the acknowledgement that I am a large person, and it makes sense for me to burn more calories for the same time and intensity of work as a fit person, but look below and tell me if you think I can trust the data.

Age: 33
Height: 6'2"
BW: 315 pounds
Duration of Exercise: 17m37s
Avg HR: 160
Calories Burned: 339

I got sweaty and everything, but that calorie output seemed high. I checked it against three or four online calories burned calculators that take age, height, and weight into account, and 339 seems plausible, but dang. Any input or thoughts on this? Can I trust the data? TIA.

Replies

  • MeanderingMammal
    MeanderingMammal Posts: 7,866 Member
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    Too many unknowns to determine to be honest, but it looks about double what I'd expect for that duration at a moderate to low HR.

    Did you pedal steady paced throughout? What sort of resistance were you pedalling against, what sort of bike trainer do you mean; turbo trainer, exercise bike, wattbike?
  • scottrey
    scottrey Posts: 18 Member
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    Mag trainer with my road bike. Intervals with variable resistance through changing my gears. 160 BPM average isn't necessarily moderate, though. If it is it's on the high side of moderate.
  • MeanderingMammal
    MeanderingMammal Posts: 7,866 Member
    edited February 2017
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    scottrey wrote: »
    Intervals with variable resistance through changing my gears.

    That renders any HR based estimation of calorie expenditure pretty meaningless then. The estimate is certainly high, what you don't know is how high

    And fwiw, at 33 I'd be looking at 160bpm as mid aerobic range, so something you can sustain for a couple of hours.
  • scottrey
    scottrey Posts: 18 Member
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    Good insight. Thanx
  • Azdak
    Azdak Posts: 8,281 Member
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    scottrey wrote: »
    Hi all. I have a HRM strap from Polar that I connect to my phone via bluetooth. I used Edomondo to record a short test session on my bike trainer, and I'm not sure if I trust the accuracy of the report it gave me for calories burned. I will preface the below stats with the acknowledgement that I am a large person, and it makes sense for me to burn more calories for the same time and intensity of work as a fit person, but look below and tell me if you think I can trust the data.

    Age: 33
    Height: 6'2"
    BW: 315 pounds
    Duration of Exercise: 17m37s
    Avg HR: 160
    Calories Burned: 339

    I got sweaty and everything, but that calorie output seemed high. I checked it against three or four online calories burned calculators that take age, height, and weight into account, and 339 seems plausible, but dang. Any input or thoughts on this? Can I trust the data? TIA.

    That suggests a workout intensity of 8+ METs which might be a little high, like about 15-25%. Also at least 40 of those calories are one you would have burned at rest, so I would estimate more like 250-275 net calories.

    Now I'm just guessing at your fitness level, but so is the HRM program.
  • OldAssDude
    OldAssDude Posts: 1,436 Member
    edited February 2017
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    It looks about right to me...

    http://www.shapesense.com/fitness-exercise/calculators/heart-rate-based-calorie-burn-calculator.shtml

    As you lose weight and get to a better fitness level you should burn less calories.

    Also, to improve your fitness level you should probably work toward keeping your heart at that rate for at least 20 minutes (30 minutes would be better).

    Also, The heart rate monitor is just recording your heart rate (Polar H7 is very accurate btw), but it's the algorithm the app uses that calculates the actual calories burned. You can download and test several apps and may get different results.
  • scottrey
    scottrey Posts: 18 Member
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    Thanks. I wasn't trying to do a full workout. I just wanted to test out the setup, especially with the HRM. I was mostly surprised at the calorie count the algorithm gave me because I'm fairly fit (very for my size). I usually lift heavy and don't do much cardio, but have recently moved back to a state that has mountains, and would like to get back into mountain biking after a long hiatus. I intend to do 45-60 minutes sessions on the trainer to get in riding shape. I honestly don't care much about the calorie count, as I view this new regimen to be a facilitator for an activity I want to do, not a weight loss activity. Anyway, thanks for the thoughts.
  • sijomial
    sijomial Posts: 19,811 Member
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    bcalvanese wrote: »
    It looks about right to me...

    http://www.shapesense.com/fitness-exercise/calculators/heart-rate-based-calorie-burn-calculator.shtml

    As you lose weight and get to a better fitness level you should burn less calories.

    Also, to improve your fitness level you should probably work toward keeping your heart at that rate for at least 20 minutes (30 minutes would be better).

    Also, The heart rate monitor is just recording your heart rate (Polar H7 is very accurate btw), but it's the algorithm the app uses that calculates the actual calories burned. You can download and test several apps and may get different results.

    As regards the bold....
    No that's completely backwards!

    As you get fitter you are able to burn more calories. That's why the fittest riders win races - they can produce more power for longer.
    Your body weight is a virtual irrelevance on an indoor bike trainer (unless you are standing up!) as it's not a weight bearing exercise.

    315cals for under 18 mins would be surprising unless you are a good standard of cyclist.
  • MeanderingMammal
    MeanderingMammal Posts: 7,866 Member
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    bcalvanese wrote: »
    As you lose weight and get to a better fitness level you should burn less calories.

    Also, to improve your fitness level you should probably work toward keeping your heart at that rate for at least 20 minutes (30 minutes would be better).

    On a turbo trainer weight has absolutely nothing to do with power output. It is relevant out in the real, particularly in hilly terrain as it's all mass that requires elevating.

    Improving fitness should mean higher power output, which means greater expenditure, not lower. In the real, lower body mass means an improved power to weight ratio, which converts to either improved speed or distance.

  • MeanderingMammal
    MeanderingMammal Posts: 7,866 Member
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    scottrey wrote: »
    Thanks. I wasn't trying to do a full workout. I just wanted to test out the setup, especially with the HRM. I was mostly surprised at the calorie count the algorithm gave me because I'm fairly fit (very for my size). I usually lift heavy and don't do much cardio, but have recently moved back to a state that has mountains, and would like to get back into mountain biking after a long hiatus. I intend to do 45-60 minutes sessions on the trainer to get in riding shape. I honestly don't care much about the calorie count, as I view this new regimen to be a facilitator for an activity I want to do, not a weight loss activity. Anyway, thanks for the thoughts.

    If your trainer is compatible then you might want to look into the TrainerRoad or Sufferfest services, that will be able to work with speed and cadence to give you a better readout on your sessions. Both also have training plans that will help you improve in a structured way and prepare for the season.
  • Machka9
    Machka9 Posts: 25,203 Member
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    Personally, I wouldn't use an HRM for calculating calories ... that's not what they're for.
  • LeoT0917
    LeoT0917 Posts: 206 Member
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    Machka9 wrote: »
    Personally, I wouldn't use an HRM for calculating calories ... that's not what they're for.

    Although HRM's only allow you to estimate calories burned, they are really the best convenient way to do this. Check out:

    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


  • LeoT0917
    LeoT0917 Posts: 206 Member
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    sijomial wrote: »
    bcalvanese wrote: »
    It looks about right to me...

    http://www.shapesense.com/fitness-exercise/calculators/heart-rate-based-calorie-burn-calculator.shtml

    As you lose weight and get to a better fitness level you should burn less calories.

    Also, to improve your fitness level you should probably work toward keeping your heart at that rate for at least 20 minutes (30 minutes would be better).

    Also, The heart rate monitor is just recording your heart rate (Polar H7 is very accurate btw), but it's the algorithm the app uses that calculates the actual calories burned. You can download and test several apps and may get different results.

    As regards the bold....
    No that's completely backwards!

    As you get fitter you are able to burn more calories. That's why the fittest riders win races - they can produce more power for longer.
    Your body weight is a virtual irrelevance on an indoor bike trainer (unless you are standing up!) as it's not a weight bearing exercise.

    315cals for under 18 mins would be surprising unless you are a good standard of cyclist.

    Actually, the original posted reply is correct. Many people confuse power output with effort (calories burned) needed to produce that output. Starting from a rested state, an Olympic cyclist working for the same period of time to pedal the same "distance" would have a lower average heart rate and burn fewer calories.

    Also, the reason that the fittest riders win races by PRODUCING more power for longer, is not because they can burn more calories. It's because the energy they consume is used more effectively and efficiently to produce more power and speed. Of course in road racing, strategy (when you choose to expend your energy, etc. ) team work, etc. also play a big role in winning.

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