Which is a better way to stay hydrated while hiking outdoors: large quantities at infrequent intervals or smaller amounts frequently?
September 27, 2010 8:34 AM   Subscribe

Which is a better way to stay hydrated while hiking outdoors: large quantities at infrequent intervals or smaller amounts frequently?

Obviously this depends on the details, but I'm curious how it depends on the details. For starters, suppose it's a mild hike with little elevation change (not enough to trouble most active people), 1-2 hours long, in a desert environment. Would it be at all sensible to drink all your water up front for such a thing? Somebody once gave me that advice, and the way they phrased it made me think that they were getting their hydration advice from the Fremen of Arrakis, which would seem reasonable to me if we were hiking in stillsuits. So I guess the short version of the question is how long (and/or strenuous) a hike would you have to be taking before drinking all your water up front would be a bad idea. (Let's leave aside the fact that you should always have extra water in case you get stuck longer, the weather is hotter, or the hike is more difficult than you thought. So when I say "all your water", I don't really mean all your water.)

There was this question back in April, which is closely related, but it degenerated into an argument about whether you should drink before you're thirsty*. This is not really the part of the issue that I'm most curious about right now.

*Sadly, the argument seemed to consist of the drink-before-thirst people saying "Well by definition, if you're thirsty, your body needs water," and the skeptics saying "Can somebody please cite a study that actually proves this?" There was nothing resembling a resolution. If you feel you must get into this here, recognize that it's a contentious issue, so don't do it without evidence beyond "common sense".
posted by ErWenn to Health & Fitness (10 answers total) 2 users marked this as a favorite
Your body doesn't really store water. It takes what you need from what you provide, then dumps the rest to the bladder.

Drinking little and often means that your body can constantly take up water from your gut without having to discard any excess.
posted by le morte de bea arthur at 8:44 AM on September 27, 2010

In my experience, it partially depends on overall temperatures, activities and how much and what sort of food you're taking in as well. The advice of drinking all of your water ahead of time in a desert is a bit of a misinterpretation around water rationing with respect to desert survival.

Your Fremen-like advice probably went something like this: "Rationing water when stranded or lost in a desert, given a constant level of activity, is a bad idea because you can misinterpret signs of severe dehydration and die before you've consumed all of your water, and when your activity is fairly constant, your rate of dehydration won't change much so you should take all of your water now because there's no benefit to taking it later and great risk at delaying" -- which is fine when you're doing it to survive the midday desert heat and wait until night to break camp and try to get wherever it is you need to go; but that doesn't necessarily translate to optimal water intake while hiking in temperate conditions.

You need water to digest food and keep yourself cool while exerting yourself. My basic rule of thumb is to have water intake match food intake, plus a little extra. If you're eating on a fairly frequent basis (ie. nibbling on a bag of trail mix or GORP) then you should have water at similarly frequent but small doses. If you're more the type to load up on a big breakfast, break for lunch with sandwiches and maybe eat an entire Clif bar in between, then you'll need to chase that with larger gulps. Add intermediate water sips for strenuous segments or just for maintenance.
posted by bl1nk at 9:07 AM on September 27, 2010

The key is to get all your body needs without taking on excess. That would be a function of temperature, humidity, elevation and your pace or activity level.
posted by JohnnyGunn at 9:46 AM on September 27, 2010

Also, the main thing is that your urine should be mostly clear yellow (unless you've been diagnossed with diabetes insipidus or you are drinking extreme volumes of water).

Drinking too much in addition to physical exertion can stress your kidneys and lead to an electrolyte imbalance.
posted by The 10th Regiment of Foot at 9:56 AM on September 27, 2010

Best answer: This is a matter of some debate in ultrarunning circles, and although probably the majority of people subscribe to the "steady drip" theory of drinking small amounts frequently, there is a vocal (and, in terms of race results, very successful) minority who subscribe to the "camel" approach wherein large amounts of water are taken as needed/at large intervals. The fact that this is not a settled question among a group of people who take seriously endurance exercise in sometimes extreme conditions, and for prolonged times, suggests that personal preference may play a large roll.

I will say that in the heat of a long day, at distances over about 25 miles, I, personally, cannot drink enough to generate appreciable urine, so it matters very little whether I'm taking in 20 ozs at once, or two ozs here and there. I'm using* all the water either way.

*Of course, urination is also a use of water, and a vital use.
posted by OmieWise at 10:22 AM on September 27, 2010

Best answer: This isn't the exact situation you're asking about, but I just read a study (Int J Sport Nutr Exerc Metab. 2010 Apr;20(2):139-44.) which indicates that smaller amounts more frequently might be better.

This study compared the effects of a rapid bolus and a slower metered water-consumption rate on urine production and postexercise rehydration. Participants (n = 8) dehydrated by 2% body weight through moderate exercise in an environmentally controlled chamber (35 degrees C, 55% relative humidity). Breakfast and lunch were standardized for all participants during each 8-hr data-collection period. Rehydration was performed using a volume of water equal to that lost during exercise either as bolus consumption (100% of volume consumed in 1 hr; BOL) or metered consumption (12.5% of volume every 30 min for 4 hr; MET). Urine volume was used to assess hydration efficiency (water retained vs. water lost) and net fluid balance at 8 hr. Mean urine outputs were 420 ml (MET) and 700 ml (BOL). A paired-samples t test showed that hydration efficiency was greater for MET (75%) than for BOL (55%; p = .018). These data suggest that metered administration was more effective in maintaining fluid balance. These findings suggest that rehydration rate is a factor in fluid-balance response. For situations in which available fluid volume is restricted, greater hydration efficiency is highly desirable.
posted by suncoursing at 10:27 AM on September 27, 2010 [1 favorite]

The best way is to hydrate well before you begin and bring enough water for you to drink throughout the day even if you didn't do the initial hydration.

The best way if you are going to be encountering multiple water sources is to hydrate well before you begin and drink a lot at every water source while carrying only about 1 liter between sources.

I don't think there is a hard rule on how strenuous the activity is compared to how much water you would be "allowed" to drink beforehand. I think that will depend a lot on the person. I can eat a lot of liquid and food with no problem before and after hard physical activities. Some people I know can't really eat anything and barely drink anything about 30minutes before to an hour after of laborious activity.
posted by zephyr_words at 11:19 AM on September 27, 2010

I'm firmly in the camel camp, mostly because I like to pee as little as possible while hiking. I drink water about a liter at a go. I don't know if its better for your body but I have noticed that I use a lot less water overall for the same amount of effort than most of my friends. And I don't have to mess around with mold growing in my camel baks and all that jazz.
posted by fshgrl at 12:31 PM on September 27, 2010

> the main thing is that your urine should be mostly clear yellow

Yes, can we get some clarification on this? It came up in a question I asked about thirst/hydration previously.

Do some people seriously claim that one's urine shouldn't be coloured at all? That it should look like water, or you're unhealthy in some way?
posted by AmbroseChapel at 8:39 PM on September 27, 2010

Response by poster: Sorry for not responding earlier. I actually forgot I'd asked this question.

Thanks to everyone for the responses. Sounds like there's still no consensus for many of these situations.
posted by ErWenn at 7:19 PM on October 1, 2010

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