Workout calorie accuracy

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david_swinstead
david_swinstead Posts: 271 Member
in Fitness and Exercise
I just got back from the gym. I used my new Polar FT7 HRM (from Santa) which said that in 20 minutes or so on the stationary bike I burned 350 calories.

Now, at 6ft 3 and 230lbs I'm aware that I'm a big guy, which means I will burn more calories than most people, but even taking that into account this calorie burn doesn't seem right to me. Surely I can't have burnt 350 calories in 20 minutes? It's way too high!

I wasn't even pushing myself much!

Does this sound right to anyone? Or if not, what might be more realistic?

Replies

  • david_swinstead
    david_swinstead Posts: 271 Member
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    FWIW the calorie counter on the machine said about half what my HRM said.

    Obviously I know that the machine isn't as accurate because it doesn't know my weight, but surely it can't be that far off?
  • david_swinstead
    david_swinstead Posts: 271 Member
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    bump?
  • EdTheGinge
    EdTheGinge Posts: 1,616 Member
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    Echo echo

    Well I'm 5"8, so a shorty but for 30mins road biking I'm burning about 300calories (not exactly pushing myself to the limit) and I'm 151lbs. So I don't think it's too far out. I use a Garmin 410
  • sijomial
    sijomial Posts: 19,811 Member
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    Agree it seems very high.

    I'm 5'9 and 175lbs and when I'm on the spinning bike I tend to see 600/hour for moderate effort and 800/hour would be right at the high end when pushing to 90% max training HR.
    1050/hour is probably attainable for your size/weight but would guess you would be really trying to hit that.

    I use a Polar FT7 as well by the way.
  • David1540
    David1540 Posts: 10 Member
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    FWIW, I'm 6'3" and 240# (clydesdale), and ride 4,000+ miles a year on the road. Garmin 305 HRM. I often see in excess of 1,000 calories per hour, last night on the trainer working a Carmichael Training Systems video (intense) I rode 18.5 miles in 62 minutes, pushing a moderate gear w/ ~90 cadence, HR average 133, said I burned 1,530 calories. Puddle of sweat on the floor.
    350 in 20 min = 1,050 / hour, I'd say you'd have to be pushing it some to really do that - what was your HR? Just spinning the pedals won't burn those kind of calories.
  • hamilton040
    hamilton040 Posts: 60 Member
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    I'm 100kg and I ride 30min dropping in sweat and I usually burn 300/350.. Not sure if that helps but it seems like its possible and if its going off you HRM aren't they always right?
  • david_swinstead
    david_swinstead Posts: 271 Member
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    So here's one thing about this whole HRM thing that I don't understand: surely as I get fitter and fitter, my heart rate won't go as high for equivalent exercise as it does now?

    So if I run 1 mile at 6mph (10 minutes), my heart rate would currently be hitting 170 by the end.

    If I did this same run every day for 3 months (assuming I still weighed the same), I guess my heart rate would be much lower by the end of it, as my body is more accustomed to the exercise.

    Surely that doesn't mean I'm using fewer calories to do the same run?

    I don't get it :/
  • mich1902
    mich1902 Posts: 182
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    Do you know if your monitor takes into account of background calories? these are the calories you would have burned without doing exercise. I used to be a member of another site that took this into consideration but it did it for you. I know some heart rate monitors do specify on the instruction sheet if they do this. I always eat back around half of my exercise cals as i'm quite wary.
  • lambertj
    lambertj Posts: 675 Member
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    I wear a polar FT4, and am 5' 4", 130 lbs and I burn around 200-210 for 20 minutes of cardio so I don't think your burn rate is completely unreasonable.
  • lambertj
    lambertj Posts: 675 Member
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    So here's one thing about this whole HRM thing that I don't understand: surely as I get fitter and fitter, my heart rate won't go as high for equivalent exercise as it does now?

    So if I run 1 mile at 6mph (10 minutes), my heart rate would currently be hitting 170 by the end.

    If I did this same run every day for 3 months (assuming I still weighed the same), I guess my heart rate would be much lower by the end of it, as my body is more accustomed to the exercise.

    Surely that doesn't mean I'm using fewer calories to do the same run?

    I don't get it :/

    Your body becomes more efficient so you need to run faster. I used to burn a lot more calories in 15 minutes than I do now so I have to up the intensity to get my HR higher to get an equal burn. Ironically, if I work out first thing in the morning it is easier for me to max my heart rate faster.

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