Calculating Cals - MFP vs. Polar vs. Precor

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ignatiusreilly
ignatiusreilly Posts: 411 Member
in Health and Weight Loss
So I finally used my new Polar FT7 while I did 44 minutes of elliptical (heart rate hovering around 120-125 for most of it).
Here are the calorie numbers provided by my HRM, MFP and the Precor elliptical:

Polar HRM: 438
Precor: 490
MFP: 668

That's a 53% discrepency between the HRM and MFP, which is huge. I've heard on these forums before that a HRM is the most accurate method, but I welcome any informed opinions out there.

Replies

  • PhatChic1186
    PhatChic1186 Posts: 173
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    I would go with your HRM because you are using a chest strap the whole time..I have Polar FT4, and I love using it..I hate using MFP calories burned
  • CarolynB38
    CarolynB38 Posts: 553 Member
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    Yep, go with the HRM. No database knows exactly how hard you are working your body but your heart rate is a good indication. The values for me are all pretty similar for the activities I do but I know some of the activities are way off for me.
  • christadoud
    christadoud Posts: 41 Member
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    The heart rate monitor is the most accurate. MFP is basically just an estimate. I have found the HRM is pretty close to MFP on cardio but MFP is way too high for strength training.
  • melvac
    melvac Posts: 333 Member
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    HRM, all hands down. That is specific to you MFP is great but a good estimate..
  • kennethmgreen
    kennethmgreen Posts: 1,759 Member
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    Well, think about it. It's a question of data points and margin of error, yes? MFP only knows the exercise type and duration. Your watch lets you enter age, sex, weight, max HR, etc. - then you add duration and average HR over the course of the activity. Weight alone can create a huge variance in calories burned. A 250 pound person doing the same activity for the same duration (assuming similar intensity) is going to burn more calories than a 125 pound person.

    By the way, be very careful with HRM. Not all are created equal. I have a Timex HRM watch that I loved, but found that the calories reported were really high. Again, it was data points - the Timex does not allow age or sex/gender to be entered in the calculation. I am returning it and have ordered a Polar FT7 like you. From the research I've done (including seeing an independent study on the accuracy of HRM) this is a very accurate HRM, particularly for men.

    Still, it's all relative. The Polar will have a better-educated ESTIMATE that is likely CLOSER to reality. There are smarter people on here that can explain exactly how calories are burned way better than I can, but a big component that is missed/only estimated at with watches is oxygen intake. Not to mention, I suspect all HRM are reporting gross calories, when they should be reporting net calories (subtracting the calories that would have been burned had you been at rest). Anyway, I would be happy with the FT7 readings. I think they are close enough. I plan to use them as reported on the watch. Also, don't trust anything I'm saying as science - verify yourself. I'm simply reporting my understanding of things.
  • wolfchild59
    wolfchild59 Posts: 2,608 Member
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    Go with the HRM, MFP and the machines are always off for me. I actually ended up making new entries for almost kind of wiling out I do just because the MFP ones were always so off.

    Based on your age, 120-125 is pretty low for a workout level, which could be why MFP is estimating so much higher for you then you actually burned, because it probably works off of a base average for active heart rate since it can't be entered specifically. Your target range for 45 would be 122-149, so you're barely reaching that level. Try a higher resistance/faster pace and get your heart rate up near the higher end and your calorie burn will go up.
  • solpwr
    solpwr Posts: 1,039 Member
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    It is critical when using an HRM to enter the right max HR. Generally 220-age works, but its just an average. For specific calorie burn information, your fitness level needs to be quantified.

    Looking at the current Polar offerings, I wouldn't buy one unless it had the Polar Fitness Test feature. Looks like FT40 and above have it. What it does is measure the R-wave to R-wave variability at rest, and then based on that plus your own fitness assessment and age, weight, and resting rate, provides a reasonable estimate of your VO2 max. This in turn provides max HR, and then the unit knows your resting rate and your max rate and can really give you a good calorie burn estimate.

    VO2 max is essentially cardio efficiency. But this is reflected in other metrics like resting heart rate (numbers as low as 26 have been recorded in exceptional endurance athletes). As your cardio system efficiency increases, your bodies' use of fuel is more efficient, and you don't burn as many calories.

    Where you are on that fitness spectrum is what the device attempts to establish. MFP and Precor don't do that. They use database averages. It does know your weight, gender, and age. But your relative fitness is just assumed to be "average". If you are unfit, MFP will be low. If you have some fitness, it will be high, in general.

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