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HRM Accuracy

Nat1982Nat1982 Posts: 31
edited May 2007 in Road beginners
Hi

Today a bought a polar F11 and tried it out. i rode 23 miles in about 90mins. the HRM says i burn't 952 calories but my cycle computer says i burnt 642, which is more accurate? The ride was fairly flat with quite a few short hills.

Av speed 15mph

Values according to F11[/u]
Rest HR 58
Max HR 175 89%
Av HR 149 76%
VO2 57

The F11 seems very accurate for my resting heart rate.

Thanks[:)]

Posts

  • GreenbankGreenbank Posts: 731
    Compare different readings (i.e. for different rides) between the same equipment, but not the same ride with different equipment.

    Personally I ignore all calorie counts and just look at average speed, average HR and time spent exercising.

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  • HungryColHungryCol Posts: 532
    600 seems low for 1.5 hours exercise.

    I'd tend to believe the F11 but Greenbank is right, concentrate on keeping your average HR within set limits giving rise to consistancy in aerobic exercise. Ideally I try to keep my HR between 70 and 80% on long rides. Stops me from being too wasted towards the end of the ride.




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  • gkerr4gkerr4 Posts: 3,408
    I'd go on the F11 - although I'd also agree that both are suspect.

    Only the HR monitor knows how hard you personaly worked across that session - by taking what it knows about your size, weight, sex etc and using some unknown calculcation about how much 'work' your body has performed.

    use it as a guide to how much you have done today versus how much you did yesterday and it can be effective - but not as an accurate science on how much food you should be taking to recover from a ride or anything like that.
  • sloboysloboy Posts: 1,139
    The problem with HRM based calorie calculation is that VO2max estimate (IIRC Polars derive that estimate by looking at your resting HR, perhaps - depending on model - also looking at heart rate variability at rest). In effect they're trying to calibrate your HR scale into oxygen consumed, energy used etc.

    If the VO2max were well calibrated, there's no reason why this wouldn't be a reasonable estimate.

    Assuming your cycle computer doesn't have an altimeter, it's probably using estimates of your frontal area to get aerodynamic drag estimates and then using speed to try to get a handle on the amount of effort expended.

    If you look at a page such as this

    http://www.kreuzotter.de/english/espeed.htm

    its analysis would say that both estimates are possible depending on hilliness. Not very hilly (say less than 0.5% rise) puts you round about where the 'puter says, undulating (say about 1%) puts you closer to the Polar, flippin' hilly (a TdF mountain stage will have about 2.5% of climbing) will put you at 30-50% more than the Polar.
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