Calories Used in an hour of cycling?

Discussion in 'Cycling Training' started by dazed&confused, Sep 2, 2004.

  1. dazed&confused

    dazed&confused New Member

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    In another thread a few people mentioned that cycling only burns 500 cals an hour. Yet at the "bicycling.com" web site, they have a calulator that gives you an estimate based on three items: pace, wieght of rider, and time spent riding.

    According to this tool, a 180 lb person would burn 490 cals per hour at the ultra slow pace of "10-11.9 mph". That same person riding at "14.0-15.9 mph" would burn 818 cals.

    Does this seem even remotely accurate to you? I have been using it to help track cals in and out.
     
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  2. Michuel

    Michuel New Member

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    Yes 8cal/minute for cycling seems OK. Standard exercise physiology textbooks give 8cal/min for easy rides rising to 15-20cal/min for hard rides for an average person. I notice on another thread on rec.bikes that Merckx, Armstrong etc would use around 30cal/minute on rowing machines(?). From memory I think walking is 2-4cal/minute.
     
  3. tanggoman

    tanggoman New Member

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    I burn about 800-900 cals on a moderately to high intensity.
     
  4. gruppo

    gruppo New Member

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    I haven't seen the calculator you mentioned, but it seems to leave out the important variable of intensity, e.g. are you cycling up a hill or on the flats? Pace, weight, and time would be the same, but the calories/energy used would be very different.

    The problem with most such rules-of-thumb and simple calculations is that they assume some mythical average but don't tell you what "average" is. You cannot state that cycling burns X calories per hour or minute without knowing a lot more information.
     
  5. Shreklookalike

    Shreklookalike New Member

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    Another problem with tables that use miles or kilometers per hour as a factor is that they don't take bicycle type into consideration. Riding a mountain bike at 13 - 15 mph is certainly a more vigourous workout than riding a road bike at the same pace.
     
  6. jpwkeeper

    jpwkeeper Member

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    Back when I used to rollerblade I read a fascinating thing: Covering the same distance burns the same amount of calories no matter what the speed, roughly.

    So, if you walk 10 miles, or run 10 miles, you will burn the same number of calories. Likewise, if all else is equal and you bike the same course at two different speeds, you will burn the same number of calories.

    The rub, of course, is that you would burn them in a shorter amount of time.

    I'm sure it's slightly more complex than that, but still fascinating stuff.
     
  7. KMKS

    KMKS New Member

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    on the intensity issue...they do list the speed but also note moderate intensity, low intensity, etc... as well. it's rough, but it's probably a decent starting point.
     
  8. Mansmind

    Mansmind New Member

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    I've seen the calculators that take intensity into account. What I haven't seen is a calculator that can take into account wind, or riding 20mph over flat ground as opposed to riding 20mph over rolling hills or climbing.

    I don't know how accurate HR monitors are for calculating calories burned, but using the "speed calculation" and then comparing it to what my HR monitor tells me, are vastly different. Then again I ride a lot of steep hills.

    As an example, on one of the normal routes I take (about 20 miles), the calculator will give me a number of 800-900 calories at my average speed, while the HR tells me I burned more like 1500. Although I don't know for sure, I would think the HR monitor is calulating based on your weight, as well as your heartrate during real-time. Seems more accurate, but perhaps not.

    John
     
  9. gruppo

    gruppo New Member

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    Can you provide a link to this calculator. I visited the site but couldn't find it. Otherwise we are just shooting blind by commenting on whether it might be reliable or not.
     
  10. dhk

    dhk New Member

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    Another way to approach this question is from the power/energy output. If I've read the energy conversion right, a kcal is equivalent to 1.16 watt-hours.

    Figures I've seen say most of us have a metabolic efficiency of about 25%. IE, we get about 1 kcal of work to the pedals for every 4 kcals we burn. If true, for every watt-hour of energy we produce on the ride, we burn about 4.64 kcals.

    Then for a good recreational pace of 150W output (around 1718mph on a level?), we'd burn 696 kcal per hour. Riding harder, at say 200W, would burn 928 kcals.
     
  11. Mansmind

    Mansmind New Member

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    Hmmm.. using what you're saying, I could almost back calculate my average wattage for a ride, correct?
     
  12. KMKS

    KMKS New Member

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    ask and you shall receive gruppo
    it's down at the bottom...
     
  13. jon_stewart

    jon_stewart New Member

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    I did 1 hour at reasonable pace for me (about 21mph) today, and burnt 780 KCal, according to Polar HRM; weight is 190lbs and ave heartrate was 144 bpm.
     
  14. Doctor Morbius

    Doctor Morbius New Member

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    Bicycling.com calculator (bottom of page) ...
    http://bicycling.com/training/0,3317,s1,00.html

    Fitness Partner Activity Calculator...
    http://www.primusweb.com/cgi-bin/fpc/actcalc.pl

    It's important to keep in mind that these are only very rough approximations. These calcs do not take into account one's percentage of bodyfat. Bodyfat does not burn too many calories during exercise or any other time. A lean 200 LB person (5% bodyfat) is going to burn more total calories during exercise than a fatter 200 LB (25% bodyfat) person given they ride the same speed on the same course at the same time given that they have similar levels of fitness and the same average heart rate (i.e. all other variables being held constant).

    My assumption on these calcs is they are for road riding on the flats. These figures are very close to the numbers I used to get with my Polar A5, which is another approximate value but is probably more accurate as it takes into account one's working heart rate. I've since bought a different HRM and the calorie counting function isn't even close to being accurate.

    Both of these calcs show that I burn over 1000 calories for an hour riding between 14.0 - 15.9 MPH. My average road bike ride is around 15 MPH.
     
  15. ric_stern/RST

    ric_stern/RST New Member

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    Typically, gross mechanical efficiency is 20 - 25 % for most people including recreational cyclists or elite TdF pros.

    1 kcal is 4.18 kj, thus if we know the average power that someone produces during a cycle session and the time that they rode for, then we know the amount of work they did, e.g., 200 W for an hour = 720 kj (0.200 x 3600 sec).

    720 kj would be ~ 172 kcal. However, we're 20 - 25% efficient, so we'll have expended ~ 688 to 860 kcals. as you can't know your efficiency unless you measure expired respiratory gases, we have to estimate it. for ease of calculation a good ball park figure is basically to say whatever energy you expended in kj, is your kcal expenditure (i.e., in this example, may as well say you expended 720 kcal).

    efficiency varies with conditions, topography, *cadence* (efficiency decreases at higher cadences) and the absolute power you ride at (higher power = more efficient).

    back to the question at hand: it's pretty hard to estimate energy expenditure from speeds and body mass, it's unlikely to be anywhere near accurate. the best you can do is use a power meter and go from kj expended.

    ric
     
  16. menglish6

    menglish6 New Member

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    I was just going to add that that calculator is most likely severly inaccurate. I just put a recent workout I did that took me around 52 minutes and it said I'd expended 1400 calories. Having spent an inordinate amount of time on a rowing machine that measures both watts and calories (i mention the watts because i figure it makes the calorie calculation more accurate) this strikes me as a pretty high calories per hour value of ~1600. I'd have been hard pressed to complete 10-15 minutes at 1600 calories/minute on the rowing machine when I was in peak condition. Definately dramatically different levels of exertion between the two, and I was much better at rowing than I'll ever be at cycling.
     
  17. dhk

    dhk New Member

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    You are correct. I didn't take time to write down the equations above, and multiplied rather than divided. Instead of 4.64 kcals (4 x 1.16) required for every watt-hour at 25% efficiency, it would be 4/1.16, or 3.44 kcals. So, agree that 200W work~688 kcals of energy burned at 25% efficiency.

    Sorry about my poor math here; didn't intend to mislead anyone.

    Also agree formulas based on speed and estimated power required would be inaccurate; a power meter would be the only accurate way to measure.
     
  18. Beastt

    Beastt New Member

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    As odd as that may sound it does make some sense if you consider that a given amount of energy is necessary to produce a given amount of work. Transporting your own weight a particular distance requires roughly the same amount of energy be produced. When your body produces energy, it does so by burning nutrients which may be measured as calories.

    From that point it starts to get more confusing, considering metabolic efficiency and various other factors even including the weight of the bike. Even to the point of complexity illustrated by ricstern which I have to admit, I couldn't follow completely. I'm sure based on reading his past posts that he's correct.

    Having said that, my software works in conjunction with my heart rate monitor and utilizes age, weight, heart rates (measured every 60 seconds), ambient heart rate and time, to calculate calories burned. I'm sure it's a rough estimate at best. Choosing a ride record at random, it shows 1098 calories, (Kcals) burned in 1-hour, 42-minutes. Which is 10.7 calories per minute or 645.8 calories per hour.
     
  19. wyllisx2

    wyllisx2 New Member

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    Umm all the above considered, what are you trying to accomplish?
     
  20. jws

    jws New Member

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    This does not work for cycling because of the speeds and hills. Aero resistance is proportional to the cube of speed, so it takes more wattage(energy per time) to ride faster; but it also takes more energy per distance because of the cubic relationship.

    Get a power meter if you want to know work output which will get you within 10% of actual calorie expenditure....closer if you have an idea of your general GME(gross mechanical efficiency), gotten from a lab test. That use for a power meter is just a bonus beyond the normal benefits of training with one.


     
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