Should I trust my HRM or MFP?

bellarosa31200
bellarosa31200 Posts: 24 Member
edited November 28 in Fitness and Exercise
I have a Polar FT4 HRM they I have started using again. I went for a run yesterday and it said I burned 944 calories for 1 hr and 46 minutes. I do a combo of walking and then running. My running app tells me that I'm averaging 13 minutes per mile so I log that into MFP as walking 4.5 mph and it tells me I'm only burning 648 calories. I feel like the HRM would be more accutate but I've also seen people say that MFP overestimates the calories burned from exercise. The only thing I can guess is that maybe I am burning more because I do run for parts and maybe that speeds things up. I'm just trying to be as precise as possible because I do eat some of the calories back. Any guidance would be much appreciated.

Replies

  • BrianSharpe
    BrianSharpe Posts: 9,248 Member
    edited January 2016
    MFP is probably closer to reality.....how far did you go? For running use .63 x weight (in lbs) x distance (in miles), walking same formula but the factor is .30.

    The problem with may HRMs is that they correlate HR to caloric expenditure, depending on how quickly your heart rate recovers on a walk break your HRM probably thinks you're still running rather than walking (it has no way a gauging pace as GPS unit would)
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  • brianpperkins
    brianpperkins Posts: 6,124 Member
    The reality is that both numbers are probably inflated. HRMs can come close for steady state ... not walk/run intervals. Running burns about twice as many net calories per mile as walking due to the difference in biomechanics ... a HRM can only plug a single data point into a formula, in this case based on running, to produce an estimate. It cannot differentiate when you are walking and running so it uses the wrong formula for every second you walked. The running app also bases your caloric burn estimate on a formula for running ... not both activities ... resulting in overestimation.

    http://www.runnersworld.com/weight-loss/how-many-calories-are-you-really-burning?page=single

    Figure out how many miles you ran and how many you walked. Plug your data into the formulas for net calories in that link and see what the estimates are.
  • brianpperkins
    brianpperkins Posts: 6,124 Member
    bellarosa31200 wrote: »
    It was 7.5 miles so using your formula it would be 605 calories. I think you might be right because my HR does get quite high. It's usually around 190 when I'm running and then goes back down to about 150 during the walking bits.

    That 605 is if you ran the entire distance. How much did you walk? How much did you run?
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