Questions about calories burned on a ride

Discussion in 'Cycling Training' started by starship, May 26, 2006.

  1. starship

    starship New Member

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    I would think that most software uses standard date tables or calculations for determining calorie burn.

    My Polar CS200 knows my resting heart rate, and can measure the duration and intensity of my ride.

    Should I trust the Polar's data for calories burned as more accurate? :confused:

    (Yes I'm tracking calories to get a deficit of 500+ calories a day) :rolleyes:
     
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  2. DennistheMennis

    DennistheMennis New Member

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    I use MySportTraining with the add-on "Food" module. With this I managed to get my weight down those last elusive 5 lbs to near-perfect race weight: 147 lbs, 5.9% body-fat! Don't want to go much lower or I risk becoming sickly, and my recovery times will be lengthened too.

    It has a built-in calculator to determine calories burned, based on perceived exertion, time/distance etc., that works surprisingly well. I know this because it not only matches my HRM's number pretty well, it also knows to deduct the amount I'd have burned anyway by driving to work instead of riding. I happen to know my resting metabolic rate (though you can also estimate it in the software), so it knows that I would burn 80 cal/hour just sitting down, and once I deduct that amount from my HRM's reading they agree extremely closely. Also, the calories intake vs. expended numbers agree pretty closely over the last two months with my weight loss, so I'd say I'm very impressed with the various standardized calorie-burning equations, wherever they may come from. I do go with my HRM's number though, and just remember to deduct 80 cal/hour.

    You can get MySportTraining for your Windows PC, Windows Mobile handheld, or Palm OS handheld from http://www.vidaone.com, or http://www.handango.com. Can also directly read Polar S-series HRMs so you don't have to manually enter in your stats after each ride.

    I don't work for them or anything; just a happy customer.
     
  3. starship

    starship New Member

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    Thanks for a very well written responce!
    I am at there web site looking now. I have been using Dietpower to track calories and exercise. But entering what my Polar said. I will now adjust down.

    I am now trying to get below 200 lbs, (8 more to go). Thanks again for the input!



     
  4. melslur

    melslur New Member

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    Check out Tom Danielson's comments at www.race2replace.com, then "Race2Replace", "Watch the webisodes", "Webisodes - show clip listings", then "Casa de Tom Danielson".

    He says at about 1:05 before the end that he biked 6 hours, burning an extra 1000 calories. He's a pro, so he must know something, but I don't see how 6 hours at any sort of intensity (even 20 km/hr) could only be 1000 calories. But nonetheless, have a look.
     
  5. DennistheMennis

    DennistheMennis New Member

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    Maybe he means that he burned "an extra 1000 calories," as you say, by adding in some extra miles or something, not 1000 total for the whole ride. I have burned 1000 calories in one hour of racing.
     
  6. ric_stern/RST

    ric_stern/RST New Member

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    There are a couple of ways of estimating and finding out how much energy you expend

    1) expired respiratory gases are measured as these show which substrates (e.g. carbohydrate) have been 'burnt' and how much

    2) you use a power meter to 'ballpark' the energy expenditure of a ride. However, these don't take into account your efficiency, which however, remains within a fairly tight range (~ 20 - 25% for trained, or elite cyclists)

    Measuring energy expenditure via HR isn't accurate. If it was we wouldn't need power meters as power is work done (energy expended) / time

    Ric
     
  7. wilmar13

    wilmar13 New Member

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    Just for anecdotal evidence... on a recent hard ride 102 miles with 12,000' of climbing, total time 5hr40min, Polar's "own Cal" estimated I burned 2530 Cals. By power data, I had done 5271KJ of work... which by Rics eff estimate puts me somewhere between 4400 and 5500 Cals burned. Looking over lots of exercise files, Polar consistently underestimated by a factor of 2, and this is with my correct height/weight/activity-level/age, etc. :eek:

    I was trying to lose a couple lbs safely, counting calories, but losing weight way faster than I should have been (I had a spreadsheet to sum total calories, theoretical weight based on surplus/deficit, compared to actual weight) and ended up binging gaining back, being on a yo-yo diet. Initially I figured "well you are as lean as you can get without incredible determination" but... now that I do the same thing with power data, my theoretical and actual weight are consistent (with normal variance of actual weight due to hydration, etc.) and no binge fests brought on by 10,000 Cal weekly deficits.

    If you are 5-10 lbs over weight it probably doesn't matter that much, but if you are already 7% BF, and trying to lose and maintain the last couple lbs, you need your caloric intake/expenditure to be as accurate as possible, and the bottom line is the Polar estimate is way low for my cycling efforts.
     
  8. DennistheMennis

    DennistheMennis New Member

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    Wow, wilmar13, your results are soooo different from mine that I have a hard time believing there isn't something wrong with your HRM. I'm just using a cheap Timex Iron Man HRM... Polars should be at least as good. Could it be the chest strap isn't snug enough so it's cutting out some of the time? BTW, that sounds like quite a ride. My club puts on a century called The Santa Cruz Mountains Challenge that's very similar in specs. It's a tough one.

    Anyway, there's no doubt a power meter should be closer as it measures the actual force applied to the pedals, while a HRM just estimates that force, based on typical folks, typical efficiency, etc. So if you have a power meter more power to you! Sorry, I couldn't resist that. :)

    But both a HRM and a PM are subject to variation from typical people/situations. If I understand correctly, a PM doesn't measure the force you're applying to the handlebars (white knuckles syndrome), swinging your upper body around, grinding your teeth a la Tyler; the sort of thing that still burns calories without contributing to your wattage. A HRM can factor those other efforts in, but is far more subject to individual variations with HRs and such; i.e., if you have a very low MHR (or resting HR?) your HRM will likely underestimate your effort. Does that sound right to you folks, or am I underinformed? Can PMs factor in your RMR? I'm interested, but not certain I can justify the expense of a PM to my wife...

    Something similar happens with those electrical-impedance body-fat measurers; they tell me I'm 15% fat, while skin-fold and water-tank tests tell me I'm around 5.9-7.6%. They work fine for most typical people, but get wacky at the extreme end of the range.

    But I am pretty sure that in the end we all still have to factor in our own variation from what the manufacturers assume "typical" means. Keeping a detailed food/workout log is the only way we can do that. Over time whatever software you use to track that will show you if your HRM is accurate enough or not. At that point you can either make further adjustments to your calories burned to match the actual resulting weight change, or get a PM to get more accurate results. E.g., if wilmar13 didn't have a PM he could just accept the wild discrepancy he's seeing and just double his calories burned per his HRM for an accurate result.
     
  9. wilmar13

    wilmar13 New Member

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    No, if that were true my HRM data would have holes in it... for that particular ride my avg HR was 148 and my NP was 324 watts... my max HR is around 190BPM, resting HR 40BPM and my FTP is approximately 340watts. I am 6'4"and around 190lbs. There could be something wrong with the Polar 625x that I use, because I swear I used to estimate my calories burned at close to 1000 cal/hr with another HRM a few years ago, and that would be close to what I am burning if 25% efficient work wise. Either way I will stick to power for my calorie counting.
     
  10. Robb.Astro

    Robb.Astro New Member

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    weird, my polar has me burning around 1000kcal/hour always has, and from all other accounts, it's pretty darn accurate for me.

    not sure why you have such completely skewed results dude :confused:
     
  11. starship

    starship New Member

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    Well, I'm NOT buying a power unit. Guess I'll have to trust the tables in the logging program I use.

     
  12. HoWheels

    HoWheels New Member

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    Polar HRM's have a self-test mode that gauges your "fitness" based on your resting heart-rate, weight, and height, which it uses to gauge more-accurately calories burned while riding.

    -Matt
     
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