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Thread: go pee

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    Default go pee

    You know when you are in your tent or bag and it's cold out and you have to go pee, but it's COLD out? Well go pee. When you keep extra fluids in your body your body is spending energy trying to keep that liquid heated to body temperature and from what I understand the body prioritizes keeping the core heated over the extremities. Not only that but going pee will let you feel relief and get back to some well earned sleeping.

    * you can pee in a container with a tight seal (recommend bottles over ziplock bags) and jettison the contents and container in the appropriate places the next morning. I prefer to get out of my tent with my headlamp and check out the night and once in awhile get blessed with a shooting star.


    I searched and searched but didn't see a thread on this topic specifically so I guess I get the dubious honor.

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    I doubt that "keeping it in" seriously compramizes warmth. That said, even in sub zero weather, a minute or two outside won't hurt. And I sleep better well emptied in any case. And, of course, there are those shooting stars.
    "It's fun to have fun, but you have to know how." ---Dr. Seuss

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    I don't having a problem walking outside. I don't want to live in urinal.

    And anyone who uses a ziplock has never heard of Murphy's Law.

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    Having taken thermodynamics, that is NOT how heat works. While "holding it in" will affect your body mass, heat loss through all three methods (conduction, convention, radiation) are all independent of mass of the object. They are primarily functions of surface area and temperature difference.

    This is an urban legend that I keep hearing repeated.

    They only down side of "holding it" is that it's really hard to get back to sleep when you have to pee.

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    When you reach 50 plus a pee bottle comes in handy especially when the temp. are in the teens and twenties. With men over 50 the issue is with a mild enlargement of the prostate and it puts pressure on the bladder. Iam 70 and have been using one on my many hikes for twenty years. Just make sure your alert when your ready to shoot for you dont want to have pee all over your sleeping bag and tent.

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    Quote Originally Posted by Amanita View Post
    Having taken thermodynamics, that is NOT how heat works. While "holding it in" will affect your body mass, heat loss through all three methods (conduction, convention, radiation) are all independent of mass of the object. They are primarily functions of surface area and temperature difference.

    This is an urban legend that I keep hearing repeated.
    They only down side of "holding it" is that it's really hard to get back to sleep when you have to pee.
    the body does have to wrok harder to maintain core temerature when it has an extra liter of fluid .
    empty gatorade bottle works .

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    Quote Originally Posted by hikerboy57 View Post
    the body does have to wrok harder to maintain core temerature when it has an extra liter of fluid .empty gatorade bottle works .
    ...one more reason not to drink yellow Gatorade...
    Colorless green ideas sleep furiously.

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    Wasn't there a 2007 thru hiker that exploded inside his tent while trying to hold in his pee? I thought I read that somewhere....
    Last edited by Spokes; 12-02-2011 at 16:19.

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    Quote Originally Posted by hikerboy57 View Post
    the body does have to wrok harder to maintain core temerature when it has an extra liter of fluid .
    empty gatorade bottle works .
    Can you point me to any scientific evidence of this? It is possible that it could be a physiological phenomenon. From a pure thermodynamics standpoint, however, an object with a higher mass will have the same heat loss (in BTUs) as one of lower mass if all other factors are identical (surface temp, ambient temp, surface area, insulation, surface emissivity, airflow, ect).

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    Quote Originally Posted by Spokes View Post
    Wasn't there a 2007 thru hiker that exploded inside his tent while trying to hold in his pee? I thought I read that somewhere....
    No that wasnt from pee, it was from master cleansing. and it wasnt pretty.

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    Quote Originally Posted by Amanita View Post
    Can you point me to any scientific evidence of this? It is possible that it could be a physiological phenomenon. From a pure thermodynamics standpoint, however, an object with a higher mass will have the same heat loss (in BTUs) as one of lower mass if all other factors are identical (surface temp, ambient temp, surface area, insulation, surface emissivity, airflow, ect).
    the physiology is what changes the picture.there is simply more mass to heat.you are right from a pure thermodynamics point of view.as it gets colder, the body will shut down blood flow to the extremeties to keep the area nearest the heart warm.the more fluid you retain, the more masss to heat, robbing the extremeties of blood flow.rocks dont need to manufacture heat.thats the difference.

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    Quote Originally Posted by Amanita View Post
    Having taken thermodynamics, that is NOT how heat works. While "holding it in" will affect your body mass, heat loss through all three methods (conduction, convention, radiation) are all independent of mass of the object. They are primarily functions of surface area and temperature difference.

    This is an urban legend that I keep hearing repeated.

    They only down side of "holding it" is that it's really hard to get back to sleep when you have to pee.

    Doesn't your body work to keep all of it's bits warm by circulating blood? There's no blood flow in the contents of the bladder so errr I don't know.... maybe it's just because one is awake they notice they are cold but I also feel the same if I am hunkering down during a rainy lunchbreak. hmmm
    Last edited by Mike2012; 12-04-2011 at 17:56.

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    Quote Originally Posted by hikerboy57 View Post
    No that wasnt from pee, it was from master cleansing. and it wasnt pretty.

    Yikes!!!!!

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    Quote Originally Posted by hikerboy57 View Post
    the physiology is what changes the picture.there is simply more mass to heat.you are right from a pure thermodynamics point of view.as it gets colder, the body will shut down blood flow to the extremeties to keep the area nearest the heart warm.the more fluid you retain, the more masss to heat, robbing the extremeties of blood flow.rocks dont need to manufacture heat.thats the difference.
    Sorry, the urine is already warm. It takes nothing to keep it that way inside the body. If you are cold emough that your body is robbing your extremities to heat your core, It's past time for more insulation.
    "It's fun to have fun, but you have to know how." ---Dr. Seuss

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    Quote Originally Posted by Spokes View Post
    Yikes!!!!!
    Plus 1 for sure. Another reason to avoid shelters?
    "It's fun to have fun, but you have to know how." ---Dr. Seuss

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    Quote Originally Posted by Feral Bill View Post
    Sorry, the urine is already warm. It takes nothing to keep it that way inside the body. If you are cold emough that your body is robbing your extremities to heat your core, It's past time for more insulation.
    Im not a doctor, but how did the urine get warm? and doesnt it use energy to maintain that warmth?it does take energy to warm your body, doesnt it?or am i wrong? Id like to hear from a physiologist on this one, cuz this is what ive been taught.either way, though , its a lot more comfortable sleeping with an empty bladder. Maybe Ive felt colder because i didnt want to get out of my bag?.

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    Now, my background in thermodynamics is from the engineering standpoint. But the simple fact that the surface area of your body does not change means that you are not losing more heat. As a matter of fact, since the water is already at core temp it would theoretically make it take longer for your body to reach ambient if for some reason your body stopped producing heat (greater starting btus, while heat loss remains constant). The withdrawal of blood to the core is to reduce the surface temp of your skin on the extremities, which reduces delta T vs ambient, which reduces heat loss. The surface area of these extremities is what makes them lose heat faster than your core regions.

    Having to pee in no way changes the laws of thermodynamics.

    Now, if one was extremely dehydrated they might sweat less, thus lose less heat to evaportive cooling. But that will be offset by you drinking water to make up for having peed some of it out. And heating that water will start at ambient temperature, needing to be heated up.

    For reference, heating 1 liter of water up to core temp takes about 35 nutritional calories if it stats pretty close to freezing.

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    When it first occurs to you go out and pee. If you wait you will stay awake for an hour or so thinking about peeing and THEN get out to pee.

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    Quote Originally Posted by hikerboy57 View Post
    Im not a doctor, but how did the urine get warm? and doesnt it use energy to maintain that warmth?it does take energy to warm your body, doesnt it?or am i wrong? Id like to hear from a physiologist on this one, cuz this is what ive been taught.either way, though , its a lot more comfortable sleeping with an empty bladder. Maybe Ive felt colder because i didnt want to get out of my bag?.
    I agree with the other guys. By your explanation here, one would conclude that the best way to stay warm is to go to bed dehydrated so that you don't create urine to warm. It doesn't work that way. You're forgetting that urine is excreted by the rest of your body, and that fluid was already at body temperature long before it enters your bladder. Now what may possibly happen is that your discomfort with a full bladder is causing you to flex your muscles which restricts blood flow, and you might also be moving more and causing drafts.

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    Quote Originally Posted by Amanita View Post
    Now, my background in thermodynamics is from the engineering standpoint. But the simple fact that the surface area of your body does not change means that you are not losing more heat. As a matter of fact, since the water is already at core temp it would theoretically make it take longer for your body to reach ambient if for some reason your body stopped producing heat (greater starting btus, while heat loss remains constant).
    This is the correct view. The urine was already heated. By peeing you get rid of water your body already heated, the difference in the amount of heat you'll lose is probably close to unmeasurable. Imagine if you have a hot water bottle at 100 degrees. How long will it take for the temperature of the bottle to drop to 90 degrees? What if you pour out the water. How long will take for the temperature to drop to 90 degrees.

    The reason to pee is that it's no fun sleeping and dreaming about peeing and waking up and finding yourself in a pee soaked sleeping bag and clothes. Your overall warmth is pretty much a non-issue.
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