hrm question

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lazurk
lazurk Posts: 6
in Fitness and Exercise
I have a polaris ft7 heart rate monitor. I have been using it on my walks and now doing p90. My question, is it accurate? Let me expand.

Most recent walk per Nike+ GPS
5.04 miles, durration 1:35:11, 18'52" mi or a little over 3 miles an hour. It was a slow day.

Calories burned:
Nike = 1,128
MFP at 3.0 = 892
FT7 = 723

The time before:
4.0 Miles, 1:13:16, 18'19"/mi or a bit over 3
Nike = 919
MFP= 685
FT7= 597

One more:
4.12, 1:14, 18'03"
nike= 938
MFP= 732
FT7= 579

That last one messes with me. Went further, faster and used less energy?

Help!

Replies

  • hellokatee
    hellokatee Posts: 211 Member
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    To be honest, I would trust the HRM above all the other sources. Maybe you DIDN'T expend as much energy on the last one. Maybe you didn't get your heart pumping as fast as the other times.
  • jbug100
    jbug100 Posts: 406 Member
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    No way to be completely sure which one is right. My FT4 always measures less cals than the gym equipment or mfp. Go with the lowest value and call it a day.
  • MsLadyVirgo
    MsLadyVirgo Posts: 160 Member
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    Hey there,

    I have a PFT7:

    The PFT7 facors in your resting heart rate, weight, height, and age. Your output may vary per PFT7 due to : resting heart rate, effort, snuggle of hr strap, wetness of the web portions of the band, and and proper location of the strap. So your output may vary often.

    MFP exercises were inputed by its users, and does not include the above referenced variances.

    I'm not sure about the Nike GPS, because I neve used it, and have no knowledge of it.

    I hope that this helps.
  • juliapurpletoes
    juliapurpletoes Posts: 951 Member
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    although no method is foolproof, I would trust the method that takes a continuous reading of your heart rate (not MFP) and uses your personal information to calculate.

    I have the Polar FT4.

    I have noticed on some of my walks and jogs that even though i perceive that I did the same effort as a previous time, the numbers will be different. And, usually it is because of small changes in my heart rate on which ever particular walk.

    For example.......I made the mistake of drinking super caffinated coffee one morning and noticed my heart rate was just higher to begin with, so of course I burned way more than a de-caffinated walk LOL.

    But for me and maybe for you, the more fit you become, your heart grows more efficient and healthier (endurance!!) and so your cal burns will be lower, unitl you ramp up something else during that walk/jog. Speed usually.

    I hope something I've said makes sense and could help! Best of luck :blushing:
  • chezkie
    chezkie Posts: 55 Member
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    I always go with the HRM and trust it implicitly. I also have a Polar FT7, and IMO it's amazing - does exactly what it says on the tin!

    Remember that your HRM is calibrated as per your height, weight and sex, and you will never get that kind of accuracy from other sources that only estimate. For instance, I do the same exercise program each day, and always try to put in the same amount of effort, but my calorie burn/fat burn minutes/fitness building minutes vary on a day to day basis, I guess its just natural for your body to do this. Your body also becomes accustomed to exercise which is done regularly, which is why when we try something new it seems so much harder than once we've done it a few times, so that may be why it's dropped even though you've gone further and faster.

    To sum up, I'd say trust the HRM...for me it is something that I cannot live without!
  • Azdak
    Azdak Posts: 8,281 Member
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    When it comes to walking, MFP is the winner.

    The energy cost calculations for walking are well validated (and fairly simple) and that is what MFP uses. At lower intensity levels, Polars are known to underestimate calories.

    I used 18:12 mile pace for all walks, just to cut down on the arithmetic. That gives you 564 calories per hour.

    Walk 1: 902

    Walk 2 and 3: about 690 each (again, I kind of rounded off the numbers).

    I have no idea what the Nike uses to estimate calories.

    Your actual caloric burn may be slightly higher because of your weight. The energy prediction equations are valid across a wide range of weights but at some point, just moving the larger body adds a little to the total (but no equation or table is designed to measure that).

    On the last one, you didn't use less energy--you just had a lower heart rate. The energy cost of simple aerobic activities such as walking is relatively fixed. It won't change over time--your fitness level can increase, which means the energy cost of walking a particular speed will now be a lower percentage of your maximum (because your maximum has gone up), but the actual expenditure will remain the same. The HRM will give a lower number because heart rate has gone down, but that's a false number because the HRM doesn't know your fitness level has increased.

    Bottom line: in this case the MFP numbers are most correct and the others are not.
  • Azdak
    Azdak Posts: 8,281 Member
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    although no method is foolproof, I would trust the method that takes a continuous reading of your heart rate (not MFP) and uses your personal information to calculate.

    I have the Polar FT4.

    I have noticed on some of my walks and jogs that even though i perceive that I did the same effort as a previous time, the numbers will be different. And, usually it is because of small changes in my heart rate on which ever particular walk.

    For example.......I made the mistake of drinking super caffinated coffee one morning and noticed my heart rate was just higher to begin with, so of course I burned way more than a de-caffinated walk LOL.

    But for me and maybe for you, the more fit you become, your heart grows more efficient and healthier (endurance!!) and so your cal burns will be lower, unitl you ramp up something else during that walk/jog. Speed usually.

    I hope something I've said makes sense and could help! Best of luck :blushing:

    If you are doing exercise at the same intensity, but your heart rate is elevated because of caffeine, the heart muscle itself may be working harder (beating faster), but your overall caloric expenditure is the same. The artificially elevated heart rate skews the number on your watch, but your actual calories are no different.

    The same thing happens when people exercise in the heat. Heart rate goes up, HRM calorie number goes up, but actual calories burned do not.
  • Azdak
    Azdak Posts: 8,281 Member
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    If anyone is interested on reading about this in more (and I mean more ;-) detail:


    http://www.myfitnesspal.com/blog/Azdak/view/calories-burned-during-exercise-it-s-the-intensity-not-the-heart-rate-that-counts-26524
  • mariabee
    mariabee Posts: 212 Member
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    Azdak, I heart you.

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