Calories burned while rowing

Discussion in 'Cycling Equipment' started by Ernie Trish, Apr 12, 2003.

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  1. Ernie Trish

    Ernie Trish Guest

    I have a calorie burn question.

    Various online sources indicate that a vigorous rowing session will burn about 300-350 calories per
    30 minutes depending on a lot of factors. My understanding is that these figures are measuring the
    amount of calories the muscles use for the workout. Simple enough.

    I have also been reading about calories required to help the body sweat during excersise (example
    article at: http://www.infraredsauna.net/medicalinformation.html). This reference and similar ones
    indicate each gram of sweat we produce requires about 0.586 kilo calories. Since I typically sweat
    1.4-1.5 kg (about 3.3 lbs) during a 45 minute rowing session this would be 820-880 kilo calories.

    The question I have is whether to add both the calories used by the muscles during rowing AND the
    calories used to maintain the sweat mechanism in determing how many total calories I have burned
    while rowing. Adding the 'sweat calories' more than doubles the calorie figure and as such has a big
    impact on the dieting aspects of the workout.

    Regards, Ernie
     
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  2. Jon Isaacs

    Jon Isaacs Guest

    >The question I have is whether to add both the calories used by the muscles during rowing AND the
    >calories used to maintain the sweat mechanism in determing how many total calories I have burned
    >while rowing.

    Some of points to consider:

    1. The website you are looking at is a website selling Infra-red sauna's as a method of
    weight-loss. Not exactly a trust worthy site.

    2. Consider the mechanism of sweating and how it cools you. The body only puts water on the surface
    of the skin, it does not vaporize it. Putting water on the surface of the skin does not actually
    consume much energy. It is only when that water is evaporated by the air that heat is transferred
    from the body to the air and thus the body is cooled.

    Now in a Sauna, that heat is coming from the Sauna rather than from exercise so the body does not
    actually have to provide any energy in order to vaporize that water, it is simply getting to hot
    because the Sauna is adding calories in the form of radiant heat to the body.

    So while evaporating sweat does require calories, those calories do not necessarily need to be food
    calories and in the case of the sauna, they would seem to come from the sauna rather than the
    persons metabolic processes.

    3. The body is about 25% efficient in converting food energy (calories) into mechanical energy. The
    other 75% is heat and sweating cools you off.

    If you want to do this exactly, you need to measure these things exactly and that includes measuring
    your actual energy expendature rather than just estimating it.

    Your question is sort of like asking if one needs to include the heat lost through the radiator when
    computing the fuel mileage of the car. The answer is that the heat lost through the radiator is
    accounted for via the efficiency of the engine.

    So when they suggest that you burn 350 x 45min/30 min = 525 calories rowing, this is just a guess.
    If you do the energy balance and assume a 25% efficiency, this corresponds to a value of 200 watts
    mechanical energy output and about 400 calories would be heat which then be transferred to the air
    via the evaporation of water on the skins surface.

    Jon Isaacs
     
  3. Terry Morse

    Terry Morse Guest

    Ernie Trish wrote:

    > I have a calorie burn question.

    I've been using a Polar 720 heart monitor, which produces a calorie estimate for each workout. I
    find it handy, since it gives me an idea of how much to eat that day.
    --
    terry morse Palo Alto, CA http://www.terrymorse.com/bike/
     
  4. Phil Holman

    Phil Holman Guest

    "Jon Isaacs" <[email protected]> wrote in message
    news:[email protected]...
    > >The question I have is whether to add both the calories used by the muscles during rowing AND the
    > >calories used to maintain the sweat mechanism in determing how many total calories I have burned
    > >while rowing.
    >
    > Some of points to consider:
    >
    > 1. The website you are looking at is a website selling Infra-red
    sauna's as a
    > method of weight-loss. Not exactly a trust worthy site.
    >
    > 2. Consider the mechanism of sweating and how it cools you. The body
    only puts
    > water on the surface of the skin, it does not vaporize it. Putting
    water on
    > the surface of the skin does not actually consume much energy. It is
    only when
    > that water is evaporated by the air that heat is transferred from the
    body to
    > the air and thus the body is cooled.
    >
    > Now in a Sauna, that heat is coming from the Sauna rather than from
    exercise so
    > the body does not actually have to provide any energy in order to
    vaporize that
    > water, it is simply getting to hot because the Sauna is adding
    calories in the
    > form of radiant heat to the body.
    >
    > So while evaporating sweat does require calories, those calories do
    not
    > necessarily need to be food calories and in the case of the sauna,
    they would
    > seem to come from the sauna rather than the persons metabolic
    processes.
    >
    > 2. The body is about 25% efficient in converting food energy
    (calories) into
    > mechanical energy. The other 75% is heat and sweating cools you off.
    >
    > If you want to do this exactly, you need to measure these things
    exactly and
    > that includes measuring your actual energy expendature rather than
    just
    > estimating it.
    >
    > Your question is sort of like asking if one needs to include the heat
    lost
    > through the radiator when computing the fuel mileage of the car. The
    answer is
    > that the heat lost through the radiator is accounted for via the
    efficiency of
    > the engine.
    >
    > So when they suggest that you burn 350 x 45min/30 min = 525 calories
    rowing,
    > this is just a guess. If you do the energy balance and assume a 25% efficiency, this corresponds
    > to a value of 200 watts mechanical
    energy output
    > and about 400 calories would be heat which then be transferred to the
    air via
    > the evaporation of water on the skins surface.
    >
    > Jon Isaacs

    Good answer. One thing I've seen in various studies is that with a Concept II type rower, the ratio
    of mechanical output to total energy burned is lower due to accelerating and decelerating the whole
    body mass. Greater efficiency can be achieved with a constrained setup.

    Phil Holman
     
  5. In article <[email protected]>, Ernie Trish wrote:
    > I have a calorie burn question.
    >
    > Various online sources indicate that a vigorous rowing session will burn about 300-350 calories
    > per 30 minutes depending on a lot of factors. My understanding is that these figures are measuring
    > the amount of calories the muscles use for the workout. Simple enough.

    No. It's not just the amount of calories used by the muscles. It's the total amount.

    Your body operates at about 25% efficiency, so your output would be about 200 watts.

    > The question I have is whether to add both the calories used by the muscles during rowing AND the
    > calories used to maintain the sweat mechanism in determing how many total calories I have burned
    > while rowing. Adding the

    No. The 300-350 calories figure is your total energy expense.

    Cheers,
    --
    Donovan Rebbechi http://pegasus.rutgers.edu/~elflord/
     
  6. Amit

    Amit Guest

    [email protected] (Ernie Trish) wrote in message
    news:<[email protected]>...
    > I have a calorie burn question.
    >
    > Various online sources indicate that a vigorous rowing session will burn about 300-350 calories
    > per 30 minutes depending on a lot of factors. My understanding is that these figures are measuring
    > the amount of calories the muscles use for the workout. Simple enough.
    >
    > I have also been reading about calories required to help the body sweat during excersise (example
    > article at: http://www.infraredsauna.net/medicalinformation.html). This reference and similar ones
    > indicate each gram of sweat we produce requires about 0.586 kilo calories. Since I typically sweat
    > 1.4-1.5 kg (about 3.3 lbs) during a 45 minute rowing session this would be 820-880 kilo calories.
    >
    > The question I have is whether to add both the calories used by the muscles during rowing AND the
    > calories used to maintain the sweat mechanism in determing how many total calories I have burned
    > while rowing. Adding the 'sweat calories' more than doubles the calorie figure and as such has a
    > big impact on the dieting aspects of the workout.
    >

    The total number of calories burned depends on the external work done and the extra evergy that is
    used because the human body is not 100% efficient (25% is a more likely number). The additional
    energy is dissipated as heat and I suppose one can correlate that to the amount one sweats.

    The 300-350 cal/30 min figure you quote above sounds like the total energy used, ie. it accounts for
    the inefficiency. If you have a way to measure your workload you could multiply that figure by 4 to
    get the total nuber of calories you used.

    ex. Typically I might do 1000kJ/hr accorinding to my trainer. If efficiency is 25%, and there are
    about 4 kJ in 1 cal. I'm burning 1000 cal/hr.

    I could see a rower buring about the same number of calories in an hour, but not say two times more,
    which is why I think the figure above is the approx. total energy used.

    -Amit
     
  7. Ernie Trish

    Ernie Trish Guest

    Thanks for the replies,

    If I have got this correctly, the body uses energy like other instruments at less than 100%
    efficiency. Not being dissimilar in concept, common units such as watts and joules are appropriate
    when discussing body energy. Like machines, a byproduct of inefficiency is heat which for its own
    reasons the body can't have so it develops the sweat mechanism.

    Based on the referenced article (http://www.infraredsauna.net/medicalinformation.html) I had made an
    assumption that the sweat mechanism itself was an active process (pores dilating or some such) that
    had a calorie value associate with it. I am hearing now that this is true but that it is accounted
    for in the commonly sited calorie expenditure numbers for rowing (300-350 calories per 30 minutes).

    Do I have it correct that all the calorie estimates are not measured directly but derived from
    assumptions about wattage, joules, and metabolic efficiency? Is this how the Polar heart rate
    monitors estimate calories? I am guessing not.

    [email protected] (Ernie Trish) wrote in message
    news:<[email protected]>...
    > I have a calorie burn question.
    >
    > Various online sources indicate that a vigorous rowing session will burn about 300-350 calories
    > per 30 minutes depending on a lot of factors. My understanding is that these figures are measuring
    > the amount of calories the muscles use for the workout. Simple enough.
    >
    > I have also been reading about calories required to help the body sweat during excersise (example
    > article at: http://www.infraredsauna.net/medicalinformation.html). This reference and similar ones
    > indicate each gram of sweat we produce requires about 0.586 kilo calories. Since I typically sweat
    > 1.4-1.5 kg (about 3.3 lbs) during a 45 minute rowing session this would be 820-880 kilo calories.
    >
    > The question I have is whether to add both the calories used by the muscles during rowing AND the
    > calories used to maintain the sweat mechanism in determing how many total calories I have burned
    > while rowing. Adding the 'sweat calories' more than doubles the calorie figure and as such has a
    > big impact on the dieting aspects of the workout.
    >
    > Regards, Ernie
     
  8. Phil Holman

    Phil Holman Guest

    "Ernie Trish" <[email protected]> wrote in message
    news:[email protected]...
    > Thanks for the replies,
    >
    > If I have got this correctly, the body uses energy like other instruments at less than 100%
    > efficiency. Not being dissimilar in concept, common units such as watts and joules are appropriate
    > when discussing body energy. Like machines, a byproduct of inefficiency is heat which for its own
    > reasons the body can't have so it develops the sweat mechanism.
    >
    > Based on the referenced article (http://www.infraredsauna.net/medicalinformation.html) I had made
    > an assumption that the sweat mechanism itself was an active process (pores dilating or some such)
    > that had a calorie value associate with it. I am hearing now that this is true but that it is
    > accounted for in the commonly sited calorie expenditure numbers for rowing (300-350 calories per
    > 30 minutes).
    >
    >
    > Do I have it correct that all the calorie estimates are not measured directly but derived from
    > assumptions about wattage, joules, and metabolic efficiency?

    Yes

    >Is this how the Polar heart rate monitors estimate calories? I am guessing not.

    From heart rate there must be an estimate of power output from a user programmed set-up value. From
    that an integration of varying heartrate (power output) together with say a 25% efficiency, will
    come up with an estimate of calories burned. Likely not very accurate, IMO +/- 10%.

    Phil Holman
     
  9. W K

    W K Guest

    "Terry Morse" <[email protected]> wrote in message
    news:[email protected]...
    > Ernie Trish wrote:
    >
    > > I have a calorie burn question.
    >
    > I've been using a Polar 720 heart monitor, which produces a calorie estimate for each workout. I
    > find it handy, since it gives me an idea of how much to eat that day.

    Most people have bodies equipped with hunger mechanisms that calculate how much exercise you've
    done, how many calories are in your food, allowing your body weight to stay pretty much the same no
    matter what you do.

    If I do say 2 hours my body has done the calculations and cries out until for more until I have
    taken in the appropriate amount of calories.
     
  10. W K wrote:
    > Most people have bodies equipped with hunger mechanisms that calculate how much exercise you've
    > done, how many calories are in your food, allowing your body weight to stay pretty much the same
    > no matter what you do.
    >

    That should really be past tense. Most people used to be equipped with this internal calculator.

    --
    Perre

    Remove and/or replace the DOTs as needed to reply
     
  11. Harold Buck

    Harold Buck Guest

    In article <[email protected]>, "Phil Holman"
    <[email protected]> wrote:

    >
    > From heart rate there must be an estimate of power output from a user programmed set-up value.
    > From that an integration of varying heartrate (power output) together with say a 25% efficiency,
    > will come up with an estimate of calories burned. Likely not very accurate, IMO +/- 10%.
    >

    You mean when the rowing machine says I burned 831 calories, it might not be exactly that many?

    --Harold Buck

    "I used to rock and roll all night, and party every day. Then it was every other day. . . ."

    - Homer J. Simpson
     
  12. Jon Isaacs

    Jon Isaacs Guest

    >If I have got this correctly, the body uses energy like other instruments at less than 100%
    >efficiency. Not being dissimilar in concept, common units such as watts and joules are appropriate
    >when discussing body energy. Like machines, a byproduct of inefficiency is heat which for its own
    reasons the body can't have so it
    >develops the sweat mechanism.

    Right

    >Based on the referenced article (http://www.infraredsauna.net/medicalinformation.html) I
    >had made an
    assumption that the sweat mechanism
    >itself was an active process (pores dilating or some such) that had a calorie
    value associate with it.

    The sweat mechanism is designed to cool the body like a radiator cools the body. The energy cost to
    the body ought to be compared to the energy cost of running an internal combustion engine's water
    pump. It takes a bit but it has little to do with the heat equations.

    >Based on the referenced article (http://www.infraredsauna.net/medicalinformation.html) I
    >had made an
    assumption that the sweat mechanism itself was an active process (pores dilating or some such)
    that had a calorie value associate with it. I am hearing now that this is true but that it is
    accounted for in
    >the commonly sited calorie expenditure numbers for rowing (300-350 calories per 30 minutes).

    Forget that article, they are trying to convince people to buy their equipment so that they can burn
    fat without exercising. It just doesn't work that way. Consider the water pump analogy.

    >Do I have it correct that all the calorie estimates are not measured directly
    but derived from assumptions about wattage, joules, and metabolic efficiency?

    Probably. If you have a way of actually measuring your work output, then you should be able to get a
    reasonable measurement of how much work you have actually done.

    If you were riding a bicycle equipped with a PowerTap, it would be continuously measuring your power
    output and storing it so it tells you how much actual work you have done. From that you can estimate
    the number of calories you have burned.

    But numbers like 300-350 calories for 30 minutes of rowing are just ball park figures that could
    vary by a factor of two in either direction.

    >Is this how the Polar heart rate monitors estimate calories? I am guessing not.

    I believe the Polar HRMs guess your work output based on your accumulated heart rate information.
    This again is just a guess and obviously may differ between individuals.

    Making the actual measurements of calories burned is quite complicated I believe and beyond the relm
    of trying to guess it based on HR or other factors.

    For my money, i would believe the number based on the actual work performed would be the most
    accurate, but such devices are relatively expensive.

    But please, when you see a website trying to sell InfraRed Sauna's as a weight loss technique, be
    suspicious and be cautious about buying their potentially bogus hype.

    Jon Isaacs
     
  13. Phil Holman

    Phil Holman Guest

    "Harold Buck" <[email protected]> wrote in message
    news:[email protected]...
    > In article <[email protected]>, "Phil Holman"
    > <[email protected]> wrote:
    >
    > >
    > > From heart rate there must be an estimate of power output from a
    user
    > > programmed set-up value. From that an integration of varying heartrate (power output)
    together
    > > with say a 25% efficiency, will come up with an estimate of calories burned. Likely not very
    > > accurate, IMO +/- 10%.
    > >
    >
    >
    > You mean when the rowing machine says I burned 831 calories, it might not be exactly that many?
    >
    > --Harold Buck

    What do you think Harold? Does the machine know your efficiency or your reciprocating mass?

    Phil Holman
     
  14. In article <[email protected]>, "Phil Holman"
    <[email protected]> wrote:

    > "Ernie Trish" <[email protected]> wrote in message
    > news:[email protected]...
    > > Thanks for the replies,
    > >
    > > If I have got this correctly, the body uses energy like other instruments at less than 100%
    > > efficiency. Not being dissimilar in concept, common units such as watts and joules are
    > > appropriate when discussing body energy. Like machines, a byproduct of inefficiency is heat
    > > which for its own reasons the body can't have so it develops the sweat mechanism.
    > >
    > > Based on the referenced article (http://www.infraredsauna.net/medicalinformation.html) I had
    > > made an assumption that the sweat mechanism itself was an active process (pores dilating or some
    > > such) that had a calorie value associate with it. I am hearing now that this is true but that it
    > > is accounted for in the commonly sited calorie expenditure numbers for rowing (300-350 calories
    > > per 30 minutes).
    > >
    > >
    > > Do I have it correct that all the calorie estimates are not measured directly but derived from
    > > assumptions about wattage, joules, and metabolic efficiency?
    >
    > Yes
    >
    > >Is this how the Polar heart rate monitors estimate calories? I am guessing not.
    >
    > From heart rate there must be an estimate of power output from a user programmed set-up value.
    > From that an integration of varying heartrate (power output) together with say a 25% efficiency,
    > will come up with an estimate of calories burned. Likely not very accurate, IMO +/- 10%.

    Your "must" about the set-up value is correct, but amusing, because I have a Cateye CC-HB100
    HRM/computer that, while it does provide a calories-burned estimate, has _no_ user-programmed value.

    It's basically a good, functional computer. I've had some problems with cut-out of the HR, but that
    may be just because I need to change the transmitter battery. My other dislikes are: no max HR (but
    it has average HR) and it can't save multiple wheel sizes for quick switches between bikes.

    It should be said that the bogo-calorie measurement should still be useful for comparing the
    relative amount of work done on different rides.

    --
    Ryan Cousineau, [email protected] http://www.sfu.ca/~rcousine President, Fabrizio Mazzoleni Fan Club
     
  15. Harold Buck

    Harold Buck Guest

    In article <[email protected]>, "Phil Holman"
    <[email protected]> wrote:

    > "Harold Buck" <[email protected]> wrote in message
    > news:[email protected]...
    > > In article <[email protected]>, "Phil Holman"
    > > <[email protected]> wrote:
    > >
    > > >
    > > > From heart rate there must be an estimate of power output from a
    > user
    > > > programmed set-up value. From that an integration of varying heartrate (power output)
    > together
    > > > with say a 25% efficiency, will come up with an estimate of calories burned. Likely not very
    > > > accurate, IMO +/- 10%.
    > > >
    > >
    > >
    > > You mean when the rowing machine says I burned 831 calories, it might not be exactly that many?
    > >
    > > --Harold Buck
    >
    > What do you think Harold? Does the machine know your efficiency or your reciprocating mass?

    It had better after making me program that info into it.

    --Harold Buck

    "I used to rock and roll all night, and party every day. Then it was every other day. . . ."

    - Homer J. Simpson
     
  16. Phil Holman

    Phil Holman Guest

    "Harold Buck" <[email protected]> wrote in message
    news:[email protected]...
    > In article <[email protected]>, "Phil Holman"
    > <[email protected]> wrote:
    >
    > > "Harold Buck" <[email protected]> wrote in message
    > > news:[email protected]...
    > > > In article
    <[email protected]>,
    > > > "Phil Holman" <[email protected]> wrote:
    > > >
    > > > >
    > > > > From heart rate there must be an estimate of power output from a
    > > user
    > > > > programmed set-up value. From that an integration of varying heartrate (power output)
    > > together
    > > > > with say a 25% efficiency, will come up with an estimate of
    calories
    > > > > burned. Likely not very accurate, IMO +/- 10%.
    > > > >
    > > >
    > > >
    > > > You mean when the rowing machine says I burned 831 calories, it
    might
    > > > not be exactly that many?
    > > >
    > > > --Harold Buck
    > >
    > > What do you think Harold? Does the machine know your efficiency or
    your
    > > reciprocating mass?
    >
    > It had better after making me program that info into it.
    >
    > --Harold Buck

    So what is your efficiency and how did you measure it?

    Phil Holman
     
  17. W K

    W K Guest

    "Per Elmsäter" <[email protected]> wrote in message
    news:[email protected]...
    > W K wrote:
    > > Most people have bodies equipped with hunger mechanisms that calculate how much exercise you've
    > > done, how many calories are in your food, allowing your body weight to stay pretty much the same
    > > no matter what you do.
    > >
    >
    > That should really be past tense. Most people used to be equipped with
    this
    > internal calculator.

    Ah well, it only ever did work well in one direction. No nagging mechanism to stop you eating too
    much as there is for eating too little. Could you find one person - apart from perhaps Callista
    Flockhard (sp?) - where this doesn't work.
     
  18. Andy Coggan

    Andy Coggan Guest

    "Donovan Rebbechi" <[email protected]> wrote in message news:[email protected]...
    > In article <[email protected]>, Ernie Trish
    wrote:
    > > I have a calorie burn question.
    > >
    > > Various online sources indicate that a vigorous rowing session will burn about 300-350 calories
    > > per 30 minutes depending on a lot of factors. My understanding is that these figures are
    > > measuring the amount of calories the muscles use for the workout. Simple enough.
    >
    > No. It's not just the amount of calories used by the muscles. It's the total amount.
    >
    > Your body operates at about 25% efficiency, so your output would be about 200 watts.

    This is true for cycling, but not necessarily for rowing. In particular, a significant amount of
    energy may be wasted by accelerating the body's mass with each stroke as the seat slides back and
    forth. The legs must constantly be accelerated while cycling, but due to intersegmental energy
    transfer, the energy required to do so is eventually completely recouped and applied to the pedals -
    I don't know if this is also true with respect to the kinetic energy "invested" in the torso when
    rowing, but I somewhat doubt it.

    Andy Coggan
     
  19. Andy Coggan

    Andy Coggan Guest

    "Phil Holman" <[email protected]> wrote in message
    news:[email protected]...
    >
    > "Harold Buck" <[email protected]> wrote in message
    > news:[email protected]...
    > > In article <[email protected]>, "Phil Holman"
    > > <[email protected]> wrote:
    > >
    > > >
    > > > From heart rate there must be an estimate of power output from a
    > user
    > > > programmed set-up value. From that an integration of varying heartrate (power output)
    > together
    > > > with say a 25% efficiency, will come up with an estimate of calories burned. Likely not very
    > > > accurate, IMO +/- 10%.
    > > >
    > >
    > >
    > > You mean when the rowing machine says I burned 831 calories, it might not be exactly that many?
    > >
    > > --Harold Buck
    >
    > What do you think Harold? Does the machine know your efficiency or your reciprocating mass?

    I think Harold's sarcasm would have been more obvious if he'd written "831.000000000" Calories.

    Andy Coggan
     
  20. Andy Coggan

    Andy Coggan Guest

    "Ryan Cousineau" <[email protected]> wrote in message
    news:[email protected]...

    > > From heart rate there must be an estimate of power output from a user programmed set-up value.
    > > From that an integration of varying heartrate (power output) together with say a 25% efficiency,
    > > will come up with an estimate of calories burned. Likely not very accurate, IMO +/- 10%.
    >
    > Your "must" about the set-up value is correct, but amusing, because I have a Cateye CC-HB100
    > HRM/computer that, while it does provide a calories-burned estimate, has _no_
    > user-programmed value.
    >
    > It's basically a good, functional computer. I've had some problems with cut-out of the HR, but
    > that may be just because I need to change the transmitter battery. My other dislikes are: no
    > max HR (but it has average HR) and it can't save multiple wheel sizes for quick switches
    > between bikes.
    >
    > It should be said that the bogo-calorie measurement should still be useful for comparing the
    > relative amount of work done on different rides.

    Unless, or course, it is hot...or if you ride at altitude....or if you didn't sleep well the night
    before...or if you've been sick recently....or if you're racing instead of training....or if there's
    more variability in your effort during one ride vs. another...or any of the other myriad factors
    that influence the HR-power relationship.

    Andy Coggan
     
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