Accuracy of "Calories Burned" on MFP vs. Polar FT4 HRM

lizp94
lizp94 Posts: 14
in Fitness and Exercise
I own a Polar Ft4 HRM. I didn't use it all but twice when I first bought it last year. LOL! Ok, so here I am beginning my weight loss journey this past week. Soooooooooooo I dug out the Polar Ft4 HRM and used it today. i'm confused. lol

I'll tell you why I am confused. Well, near my house I walked what they call "The Loop" and tons of people walk/jog/run it every day. It's exactly 2.5 miles from start to end.. I walked from my house to "The Loop", did "The Loop" walk and all the way back home I went. I moved at a great brisk pace to (I was dying lol).
Ok I also brought along my phone and used the Runkeeper App on it to. Here is what I got:

Polar FT4 HRM 511 calories burned time 1 hour 40 seconds average pace of 3.60
Runkeeper 375 calories burned time 1 hour 40 seconds distance of 3.46 miles average pace 3.43

Now if I log walking at 3.5 mph brisk pace for 60 minutes here on MFP found in the database it says 331 calories burned????

SO WHAT DO I USE???????????? How accurate is a Polar FT4 HRM if you have one? How accurate are those numbers in the database here on MFP?

I'll take any and all advice just be kind please I'm just starting here!!! LOL!

Replies

  • Ctrum69
    Ctrum69 Posts: 308 Member
    I'm not familiar with Runkeeper, but, does it take into account your age, size, weight?

    You and I can go walk the exact same thing, at the exact same pace, and have different calorie burns.

    (I'm also not familiar with the Polar FT4), but how is it calculating your rates?

    I have a Basis B1, which is interesting for counting steps, and paying attention to "average' heart rates, but useless (and they say up front it is!) for tracking HR in workouts.

    I also use a polar bluetooth HRM that feeds into Endomondo, to track my workouts, and I _think_ that gives me a fairly accurate idea of how many calories I'm burning, because it seems to line up with what several calculators estimate I should be burning, at my size/weight/gender and % of cardiomax.

    In other words:

    The Polar is tracking your actual heart rate. That is one way of figuring calories.

    The Runkeeper app is basing it on steps or distance/time elapsed, and guessing at your heart rate to make a statistical estimate.

    MFP is using a different algorhythym to say "you walked this fast for 60 minutes" and is not accounting for hills, variations in speed, etc.
  • brookfield58
    brookfield58 Posts: 7 Member
    As long as you have set up the HRM to your stats i would go with that. It will be accurate and is tracking your actual heart rate.
  • cwolfman13
    cwolfman13 Posts: 41,865 Member
    I would go with the lowest. HRM's are reasonably accurate for a steady state cardio event, but 500 + calories for an hour walking sounds like a lot. 300ish calories for an hour of walking sounds far more reasonable...about 100 calories per mile is a pretty safe estimate. You want to be as conservative as possible so that you're not eating back too many calories from exercise. Personally, if I were you and doing a reasonable amount of walking on a regular basis I would just put myself as light active and only worry about logging more intense/vigorous exercise.
  • Ctrum69
    Ctrum69 Posts: 308 Member
    3.6mph is a pretty fast "walk" and coming close to a jog.
  • cwolfman13
    cwolfman13 Posts: 41,865 Member
    As long as you have set up the HRM to your stats i would go with that. It will be accurate and is tracking your actual heart rate.

    Your HR is not directly correlated to calorie burn...a HRM uses your HR in an algorithm to estimate at what level of VO2 max you are at. Generally speaking your HR doesn't get up high enough for long enough walking to really be considered an aerobic event...this would throw that algorithm off as it also assumes a steady state aerobic event.

    Also, if you have any abnormalities such as a high RHR then your calorie burns would be inflated. When I first got back into exercise I had a very high RHR of 110 and I would hit 125 on a walk easy...I was getting ungodly calorie burns for very minimal effort. ONce I got on my meds and put my RHR into a normal range, my burns came more into line with what I knew they were for a particular activity.

    Always go with the most conservative estimate. Calories burned has far more to do with distance traveled than what your HR is. A HRM is in no way shape or form gospel.
  • Ctrum69
    Ctrum69 Posts: 308 Member
    As long as you have set up the HRM to your stats i would go with that. It will be accurate and is tracking your actual heart rate.

    Your HR is not directly correlated to calorie burn...a HRM uses your HR in an algorithm to estimate at what level of VO2 max you are at. Generally speaking your HR doesn't get up high enough for long enough walking to really be considered an aerobic event...this would throw that algorithm off as it also assumes a steady state aerobic event.

    Also, if you have any abnormalities such as a high RHR then your calorie burns would be inflated. When I first got back into exercise I had a very high RHR of 110 and I would hit 125 on a walk easy...I was getting ungodly calorie burns for very minimal effort. ONce I got on my meds and put my RHR into a normal range, my burns came more into line with what I knew they were for a particular activity.

    Always go with the most conservative estimate. Calories burned has far more to do with distance traveled than what your HR is. A HRM is in no way shape or form gospel.

    Well, a minor quibble: That depends on the individual. If her "cardio zone" is correctly calculated (and there are a bunch of different formulas to figure that out) and she's putting herself into a fatburning zone on her walk (I can do that easily pushing a walk, and averaging 3.8 to 4mph.. puts my HR at right about 136 which is right in my zone), then it's just as cardio as any other cardio exercises.

    I don't think, short of going and having an actual analysis done with a treadmill, 'trodes, and a breathing mask, there is ANY gospel to this. Just comparing the variables and seeing which appears to be most accurate.
  • acpgee
    acpgee Posts: 7,994 Member
    A dietician once told me that 300 kcals per hour for walking was about right, factoring in adjustments for body weight and speed. My guess would be that your heart rate wasn't high enough for the HRM algorithm to be accurate. What was your average heart rate during the walk?
  • Mr_Knight
    Mr_Knight Posts: 9,532 Member
    The correct burn number depends on your weight. At 180 pounds, for example, the net burn for 2.5 miles of walking is...

    0.3 * 180 * 2.5 => 135 calories

    Plug in your actual weight and distance as matches your particulars.

    Good luck!
  • lizp94
    lizp94 Posts: 14
    Wow I have to admit I don't even understand some of the stuff I am reading. I'm not saying this to be ignorant i'm laughing at myself. I'm so lost lol
    I used Runkeeper App just to keep track of the distance. I did move my butt while walking I surely wasn't walking slow or taking a stroll ahahahahahah!

    I'm not sure what my average HR was while walking because I cleared everything from the HRM. *SIGH* dumb move I guess.

    Thank you everyone for your input. I think i'll just put in the numbers that MFP has in the database but be careful NOT to eat all those calories back. Make Sense?

    THANK YOU EVERYONE!
  • Ctrum69
    Ctrum69 Posts: 308 Member
    Wow I have to admit I don't even understand some of the stuff I am reading. I'm not saying this to be ignorant i'm laughing at myself. I'm so lost lol
    I used Runkeeper App just to keep track of the distance. I did move my butt while walking I surely wasn't walking slow or taking a stroll ahahahahahah!

    Hehehe.. no problem. I didn't understand a lot of it till I started researching it.

    I used this site to figure out my basic numbers:

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

    That will give you a rough total caloric burn, if you plug in the numbers, as well as the ability to figure out your V02max if you want to.

    There are other formulas out there to figure out your cardio rates.

    But, plugging my info in there, if I walk an hour at my "fatburning" cardio rate.. which is 136, I will burn 850 calories, +/-
  • sydneybeachgirl
    sydneybeachgirl Posts: 209
    I would go with the numbers you get from your HRM - in my experience the exercise cal burnt numbers on MFP are overestimated...Your HRM gives a number for your effort - the numbers on MFP are an aggregate or someone who might be a completely different body type , fitness etc to you created an exercise- it is not accurate...
  • mdandres
    mdandres Posts: 15
    What I do is take the average of all my records given. If I'm at the gym and the treadmill says N and my polar watch says X, then I go (N+X)/2. Alternatively, if I go biking and my watch says X but RunKeeper says N... well you get the idea.
  • anaconda469
    anaconda469 Posts: 3,479 Member
    I bike ride lots (over 200 miles a month) and I use a Polar FT4. MFP either over estimates or under estimates calorie burns, depending on what you are doing.
  • lizp94
    lizp94 Posts: 14
    Per the Information on my Polar FT4 HRM ( I forgot it stores the info lol) :

    duration : 1 hour 40 seconds
    calories: 512 calories
    average HR 138
    Maximum HR 161
    In Zone 57:28

    My height is 5'5" and I weigh 191.8

    I walked 3.46 miles

    I'm going to give those websites a lookie in a bit...
  • tigersword
    tigersword Posts: 8,059 Member
    3.6mph is a pretty fast "walk" and coming close to a jog.
    Not really, "jogging" is usually at least 4.5 mph. 3.6 mph is about 17 minutes per mile. That's about average for walking.

    OP, they're all just guesses essentially. Pick one and go with it, and see how your weight changes. Personally I'd get rid opf the Polar, that's way off, which could just mean you've input some wrong info in the setup, or it could just be the fact that HRMs in general aren't all that accurate.
  • YorriaRaine
    YorriaRaine Posts: 370 Member
    Please keep in mind that the heart rate monitor calculates gross calories burned, to figure out net calories burned you would have to take the heart rate calorie readings and then subtract what you would have burned naturally (take your bmr and figure out how much you burn per minute).

    You can also use this calculator to cross-check.

    http://www.shapesense.com/fitness-exercise/calculators/heart-rate-based-calorie-burn-calculator.aspx
  • lizp94
    lizp94 Posts: 14
    OK everyone thank you for your input and advice. I appreciate it and thanks for being nice hahahahah! :)

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