Heart Rate Dilemma

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mightn
mightn Posts: 35
in Fitness and Exercise
I just did a pretty hard cycling session of 45 mins. I do this session once a week.

I log a moderate effort in my MFP ap and it tells me I have burned 707 calories.

I am buying a Polar FT7 on the weekend so my girlfriend lent me her HRM (it's a Pulse Sonic or something) for this session.

My heart rate was between 155 and 180 for the entire 45 mins so it was a tough session. The HRM told me I had only burnt 350 calories, a massive 350 difference from what MFP tells me.

I'm not sure what to believe. Is a cycling session of 45 mins with an average Heart rate of 165 likely to be 350 calories or 707? I am 120kg (264 pounds) and 6 foot 6 (197cm). When my girlfriend and I do the same session and log it on MFP, it tells me I have burnt about 40-50% more than her. She is 132 pounds. Do HRM recognise this weight discrepancy or is it just done purely on your heart rate?

I am confused. Help please.
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Replies

  • xraychick77
    xraychick77 Posts: 1,775 Member
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    yes..mfp way over estimates calories burned..the hrm is probably more accurate.
  • melaniecheeks
    melaniecheeks Posts: 6,349 Member
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    They are both estimates. MFPs values tend to be on the high side, heart rate monitors give better readings, but need to be set to your own statistics. Rather than over-estimate, I'd go with the lower figure.
  • SparksFly460
    SparksFly460 Posts: 258
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    Go with the heart rate monitor number but I wouldn't recommend using hers anymore because it will give you a wrong caloric burn. Most decent HRM require an initial setup of height/weight & sex....combining that with your heart rate gives you a pretty decent estimation of how many calories you're burning. So if her data is on on the HRM and you used it...well it gave you a burn based on her stats, not yours. Def get one of your own and use it for the spin class.

    I love spin also btw, take it 3-4 times a week. According to my HRM I burn between 300-450 calories each session (depending on how hard I work)
  • Tan43
    Tan43 Posts: 87 Member
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    I`ve worn my polar 4 in my RPM classes and I burn 335 for 45 minutes at a heart rate the same as yours. I weigh 153 pounds.
  • kattygirl0499
    kattygirl0499 Posts: 41 Member
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    OK...so I have a similar but opposite dilemma. I have a Timex Zone Trainer that I got today, so first time using it. I have to admit, that the number of things this thing can do is confusing - I have to sit down and do an in depth read of the manual - BUT on Sunday, I did a 50 minute C210K workout on my treadmill. My Nike+ estimated I burned 555 cals. I'm ok with that. Today, I did 35 minutes, but I compared the output of the Nike+ to my new HRM. Nike+ says 380 cals burned. HRM says - wait for it - 664 calories (!). Really? More than Nike+ estimated for my run that was 15 minutes longer? I don't know what to believe now. Oh and for what it's worth, I'm 5'6" and 186 lbs.

    Help???

    Kathy
  • mightn
    mightn Posts: 35
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    Thanks for the responses. My session was out on the open road, not a spin class. Although I know lots of people that love doing spin.

    Tan43, your numbers are interesting and are the crux of my question.

    If you at 153 pounds do a spin session with your heart rate at 165, do you burn the same amount of calories as I do as a 265 pound male, with the same session time and heart rate? MFP says definitely no.

    The other thing that came to mind is that MFP considers me obese. I am definitely not obese. I played professional football in Australia for 8 years and my whole team was obese according to those numbers. I retired a few years back and have lost a bit of muscle but I'm not too different from my playing weight.

    So maybe MFP is thinking that I am burning a huge amount of calories because to do the workout I am logging, for an obese person, would take that many- because MFP doesn't consider heart rate . But I am fit and healthy, just trying to shed a few retirement pounds.
  • _Kate_P
    _Kate_P Posts: 132
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    for most monitors, you enter weight, height, gender, and age. So that could make a huge difference if you said you were a 120lb 5' 60 year old woman vs say, a 180lb 6' 25 year old man
  • _Kate_P
    _Kate_P Posts: 132
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    for most monitors, you enter weight, height, gender, and age. So that could make a huge difference if you said you were a 120lb 5' 60 year old woman vs say, a 180lb 6' 25 year old man even if you were doing the exact same workout with the same heart rate the whole time
  • mightn
    mightn Posts: 35
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    So is there is a difference in calories burnt between a

    265 pound man exercising for 45 mins at a heart rate of 165
    125 pound woman exercising for 45 mins at a heart rate of 165
    450 pound man exercising for 45 mins at a heart rate of 165

    Have all these people burnt the same calories because they have exercised for the same amount of time with the same heart rate?
  • mightn
    mightn Posts: 35
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    Bump
  • Azdak
    Azdak Posts: 8,281 Member
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    If you borrow someone's HRM and do not reset the setup data, then it is worthless (unless the person is your twin).

    For someone of your size, 700 calories of 45 min of hard cycling is not an unreasonable number. That being said, if you are going off a calorie table, the accuracy of that number will as much coincidence as anything else. Because of differences in terrain, wind, and cycling style, it is next to impossible to use a general formula that's good in all cases. Way back when I was in my Ex Phys program, this topic was addressed specifically. The prof gave us a formula for estimating the energy cost of outdoor cycling, but then said it was useless because of the factors I mentioned above.
  • MaximalLife
    MaximalLife Posts: 2,447 Member
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    These monitors are no better than a mere guess.
    I understand that their output is dependent on the settings you enter, so make sure you're being consistent.

    Actually, 350 sounds low, 700+ sounds high.

    Enter 500 - my best guess.
  • Azdak
    Azdak Posts: 8,281 Member
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    So is there is a difference in calories burnt between a

    265 pound man exercising for 45 mins at a heart rate of 165
    125 pound woman exercising for 45 mins at a heart rate of 165
    450 pound man exercising for 45 mins at a heart rate of 165

    Have all these people burnt the same calories because they have exercised for the same amount of time with the same heart rate?

    For determining workout intensity (and, from that, calorie expenditure) heart rate is a relative number, not an absolute number. The actual number itself is irrelevant--what is important is the "percentage of maximum" that heart rate represents. Saying "exercise heart rate is 165" is meaningless; what is meaningful is if that 165 represents 40%, 50%, 60%, 70%, etc, of maximum.

    For more detail: http://www.myfitnesspal.com/blog/Azdak/view/calories-burned-during-exercise-it-s-the-intensity-not-the-heart-rate-that-counts-26524
  • 1546mel
    1546mel Posts: 191
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    I go with the lower number on my heart rate monitor as it shows how hard my heart has to work to pump the blood to my muscles. I figure that it is more accurate than the calories burned on machines or even on MFP. A normal 215-pound 6-foot female is prob way more out of shape than i am at this weight and height, so i figure i burn less calories than normal and the HRM prob does a better guessing game than estimates.
  • engineman312
    engineman312 Posts: 3,450 Member
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    you probably didn't reset the data for the HRM, including specifying you are male. yes, most HRM do guees, but it is an educated guess based on a few different data points, including sex, weight, age, and heart rate

    i'm 6' 3" 218lbs, and my last spinning session, i did 45 minutes and burned about 900 calories according to my HRM. i was dripping with sweat at the end of it, keeping my heart rate up the entire time.
  • BerryH
    BerryH Posts: 4,698 Member
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    They are both estimates. MFPs values tend to be on the high side, heart rate monitors give better readings, but need to be set to your own statistics. Rather than over-estimate, I'd go with the lower figure.
    This, BUT HRM estimates can be on the low side for an exercise you do regularly. Your heart rate tends to go down when you work out at a certain level faster than the calories you burn do.
  • scottb81
    scottb81 Posts: 2,538 Member
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    How far did you ride? For cycling you are going to burn around 40 or 50 calories per mile.
  • therealangd
    therealangd Posts: 1,861 Member
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    Can you figure out this formula? I find this to be quite accurate, if I need to figure it out.

    (-20.4022 + 0.4472 x HR - 0.1263 x weight + 0.074 x age) / 4.184
  • Amber82479
    Amber82479 Posts: 629 Member
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    Did you update her HRM with your information? If not, it thought it was tracking results for a woman who weighs a lot less than you! When you get your FT7 (got mine yesterday), you will set it up for your gender, weight, age, etc... and it will be far more accurate :) MFP is just a guesstimate, as it doesn't take into account your personal stats like heart rate. Best of luck, I think you'll really love the FT7!
  • Dtho5159
    Dtho5159 Posts: 1,054 Member
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    Definitely believe the HRM as long as you set it to your stats. If she had her stats in it (height,weight etc) and you didn't change it, it would affect your burn but MFP grossly overestimates burns.

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