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  1. #1
    3 summits of Athens
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    Am i properly hydrated?

    Several times i wonder if my fluid uptake is sufficient and what are the standards of the proper hydration. Normally i drink 200ml of isotonic drink in 20mins of ride in a cool air and more often in the summertime. Only rarely does it happen that i need to urinate after 2-3 hours of cycling though i don't feel thirsty. Does not feeling thirsty is a reliable sign of good hydration or a good fluid loading should send me behind the bushes every hour? In times when i have been compulsively drinking too much in order to fill my bladder i would feel an unpleasant balloning at my stomach that made my breathing more shallow..What about my riding buddy who is a lion on the saddle and refuses to sip a drop until we stop for rest-say 90 mins on-and even carries his bottle in his backbag!

  2. #2
    Mettle to the Pedals Dewbert's Avatar
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    A knowledgable friend of mine tells me that you're properly hydrated when your urine runs clear (or nearly so).

    Anybody else know if this is accurate or reasonable?
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  3. #3
    Senior Member DannoXYZ's Avatar
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    Quote Originally Posted by Dewbert
    A knowledgable friend of mine tells me that you're properly hydrated when your urine runs clear (or nearly so).

    Anybody else know if this is accurate or reasonable?
    Not necessarily because it can also result from other physiological symptoms as well. The rates of deaths from hyponatremia has been on the rise. It's partly from inadequate intake of electrolytes and partly from excessive water consumption. These victims have had clear urine before their deaths; they're overly hydrated. A lot of people see nutrition in clear-cut, yes/no, black&white, all-or-nothing terms of extremes (no fats, no sugars, no salts, etc.). They also go to the other extremes with "drinking water is good, so A LOT of it's even better". So they sit around watching TV and drinking water. They'll bring bottles with them everywhere and sip on water constantly.

    The problem with this is that not much excess water is stored, it's excreted out as urine. Due to the ion-gradients in the kidneys (salt-column), you cannot just pee pure-water, minerals and salts are always flushed out as well. Mineral-deficiencies are a very common ailment with those who drink only distilled water. So.. in the process of getting to the "pure" clear urine, you end up having to drink 2-3x as much water as necessary for completely re-hydration. You've dumped a whole bunch of salts and minerals out of your body as a result.

    Combined with the mistaken "no-salt" nutrition, you become severely depleted in electrolytes. Many don't realize that electrolytes must be replenished based upon activity, just like water. An active athlete will actually require 200-600% more sodium and other electrolytes daily compared to sedentary couch-potatoes. Common symptoms of low electrolytes show up as muscle-cramps and light-headedness when standing up quickly. So.. there's no simple "always" answer. Water should be consumed on an as-needed basis to replace the amounts that have been sweated away.

    Additinally, you also have to balance water vs. nutrient absorption in digestion as well. Pure water absorbs the fastest, however you also need to take in nutrients. Too high a concentration of solids or carb-complexes will slow down water-absorption. The RAAM folks sacrified water-intake for nutrient intake since they needed as many calories as possible per hour; the riders always ended the day slightly dehydrated as a result. Most people can usually settle on around a 200-cal/hr intake of nutrients with electrolytes. Then about 500-750 ml/hr of water depending upon activity intensity and ambient temperatures. A better way to judging adequate hydration level is to weigh yourself before the workout. Then weigh yourself afterwards and make sure take in enough water to weigh roughly the same (minus weight of recovery foods).
    Last edited by DannoXYZ; 01-03-06 at 04:56 AM.

  4. #4
    Senior Member DannoXYZ's Avatar
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    Quote Originally Posted by mimis
    Several times i wonder if my fluid uptake is sufficient and what are the standards of the proper hydration. Normally i drink 200ml of isotonic drink in 20mins of ride in a cool air and more often in the summertime. Only rarely does it happen that i need to urinate after 2-3 hours of cycling though i don't feel thirsty. Does not feeling thirsty is a reliable sign of good hydration or a good fluid loading should send me behind the bushes every hour? In times when i have been compulsively drinking too much in order to fill my bladder i would feel an unpleasant balloning at my stomach that made my breathing more shallow..What about my riding buddy who is a lion on the saddle and refuses to sip a drop until we stop for rest-say 90 mins on-and even carries his bottle in his backbag!
    Sounds like you're fine, so you don't need change anything drastically. What causes this "compulsive drinking"?

    Thirst is not a good indicator because with intense exercise, the elevated levels of adrenaline and epinepherine will give your brain that dopamine "high" and masks all sensations of thirst. This is part of the "flight-or-fight" survival response that is used to prevent death at all costs. A short burst of energy will let you escape a dangerous situation or fight your way out of it. Thirst and hunger are the last things you need to be concerned with in a life-or-death situation. Numerous studies have already been done with hikers and runners on this, no need to rehash it. Basically drink based upon ambient-temperatures/humidity, time and duration/intensity of exercise. About 500-750ml/hr should be fine. Surprizingly, riding in cold-weather doesn't reduce water-requirements much because the core body-temperatures will be similar anyway.

    Your buddy's gonna get heat-stroke or heat-exhaustion and die if he keeps this up. Many a hikers have died from just a couple of hours in the sun with just light exercise. Triple the intensity on the bike and he's asking for trouble...
    Last edited by DannoXYZ; 01-02-06 at 11:40 PM.

  5. #5
    Long Distance Cyclist Machka's Avatar
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  6. #6
    sch
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    You should be aware there is a limit of 750-1000ml/water or fluid that can be absorbed per hour by the gut. If you exceed this level the stomach simply fills up and serves as a reservoir. The hyponatremia hoorah has been associated with slow marathon runners who are out on the course for 5hrs or more and drink a lot. When one compares fluid uptake of water versus sugar/electrolyte solutions it turns out that a few % of sugar maximizes fluid uptake compared with water or sweeter solutions. Hence the very mild sweetness of *ade.
    Steve

  7. #7
    3 summits of Athens
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    This has been a very scientific approach to this matter doc, certainly made me wiser. It's true that few hours after each long ride i have symptoms of postural hypotension but never have had muscle cramps while riding or in any other activity. So, i should take your analysis and drink isotonics alone? I can recall the longest of my rides (200-300km last spring) how i was craving for salty food and MEAT on the last part of them! Considering i sweat too much in the summertime even at rest do you think i should drink isotonics along with water during the day?

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