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erugs
02-24-2006, 01:25 PM
Knowing how detail-oriented and inquisitive VFTT'rs are, I thought my fellow readers might be interested in some information about how we don't adapt as well to cold as we do to heat. There is an interesting story in the Winter 2006 issue of the University of NH Magazine that was just delivered to my desk here at UNH that highlights research done on cold weather and "our perception of thirst." Basically, the article briefly describes research done by ice climber/UNH associate professor Robert Kenefick. "The study confirmed what [Kenefick] suspected: in the cold, perception of thirst goes down." Basically, "this is caused by the narrowing of blood vessels and the brain thinks that the body has plenty of fluid." And oddly, the more dehydrated we are the less we recognize thirst. For info junkies, more complete info from this study has been published in the journal "Medicine & Science in Sports and Exercise." Cool, huh?

spaddock
02-24-2006, 02:39 PM
That is way cool. Thanks for that info.

I'm definitely not as thirsty in the Winter compared to summer. Gotta force more liquids into me I guess. Means I should be carrying more water too... :(


-Shayne

Jim lombard
02-24-2006, 02:57 PM
I also have to remind myself often to drink. What helps for me is drinking a big glass of water on my way to the trailhead so I'm well hydrated when I begin.

cbcbd
02-24-2006, 03:11 PM
My experiences have held true to that research. In a sense, I feel less "needy" in the winter time. Add really high altitudes to that and I also sense less hunger. It almost gives you a feeling of invincibility - you need no water, no food... and then the fatigue really hits you ;)

It's funny how the body doesn't adapt well to these conditions and that just leaves you dehydrated and out of energy.

Winter time is very much about being proactive than reactive. By the time you react it could be too late sometimes.

grouseking
02-24-2006, 03:30 PM
On the rare occasions that I do get out hiking in the winter, I do notice that when I force myself to drink, I end up realizing how thirsty I really am and I always end up drinking longer.

Speaking of, I need to go get some water. :o

grouseking

MadRiver
02-24-2006, 03:35 PM
Do you have the citation? The only article I found was published in 2004, which seems a tad old.

giggy
02-24-2006, 03:41 PM
I never have this problem - always thristy with the dry air - the problem I have is peeing too much - when hiking - not a problem - but when climbing -bit trickier - but can (and has) been done :eek: :eek:

now you wonder where all that yellow ice comes from :D :D :D

DougPaul
02-24-2006, 04:24 PM
It sounds to me like the study just agrees with/confirms what I was taught around 1974 by winter school, an "Outdoors Medicine" course by the school medical department, and/or Dr Murray Hamlett:

* The sensation of thirst is reduced in the cold. By the time you are thirsty, you are somewhat dehydrated.

* One should output .5-1 liter of urine per day. Color should be clear or light straw. (However, urine can be colored by certain foods.)

* A simpler rule of thumb is that you should drink enough that you have to pee several times during the day. Same color issues as above.

Doug

NewHampshire
02-24-2006, 04:54 PM
I learned this important lesson a couple of weeks ago on Waumbek. I bonked bad. I had to push mtself up that last pitch to the summit. I dont blame it on hydration since I sucked the magic mix (DougPauls el-chepo electrolyte drink) down like nothing (I had downed 1 and a half liters by summit.) But food was a different matter. I had eaten only a light breakfast and then NOTHING till I got to the top of Waumbek. This weekend Im going prepared. Peanut M&Ms, Granola bars, Fig Newtons, a decent sized lunch complete with cookies for dessert. Ill be well fed as well as probably being pretty popular with the group :D . Ill top that off with my customary 3 liters of fluids.

Brian

Lawn Sale
02-24-2006, 05:53 PM
I almost always forget to drink, then wonder why I either hit the wall or have a headache by the end of the day. Thus I have to force myself, and even then usually only take one or two gulps at a time. I started doing that again last summer as well, but came up with a system where I'd take a drink of water every 100' of elevation gain and stop for a quick bite every 1,000'. On the way down it's whenever I stop, but it's a system that does work for me.

I do have 4 or 5 hydration bladders I'm going to try out this summer, just to see if I can get used to them. I know a lot of people on here swear by them, so we'll see how it goes.

I know I should be drinking more, but it's not something I think about when hiking...unless I'm hiking with Magic, he's good at reminding people!

DougPaul
02-24-2006, 06:30 PM
I almost always forget to drink, then wonder why I either hit the wall or have a headache by the end of the day. Thus I have to force myself, and even then usually only take one or two gulps at a time. I started doing that again last summer as well, but came up with a system where I'd take a drink of water every 100' of elevation gain and stop for a quick bite every 1,000'. On the way down it's whenever I stop, but it's a system that does work for me.
Another system is by the clock--I eat and drink at least once an hour--generally more often. (Works on the level too. :) )

I keep food in my pocket and a water bottle in my pocket or on my belt. (Yes, I like lots of big pockets...) By keeping them readily available, I can frequently eat and drink without breaking stride (or at most a very brief stop). Bladders also work for keeping water readily available (may be difficult to use in the cold--search for threads on the topic if you are interested).

I use the above systems all year round.

Stopping for a long lunch in the cold has the disadvantage that you are likely to get cold. Keeping your stops short avoids this problem.

Another trick is to put your gorp in a wide-mouth plastic bottle. Easy to eat with mittens/gloves on and you can even eat through a facemask.

Doug

hikerfast
02-26-2006, 11:56 PM
i do atkins generally, and i put atkins shake mix in with my 2 liters of water i always bring. this is about 600 calories im drinking during the day, or more(900?) if i make them thick. they taste good so i like drinking them. one day a couple years ago i climbed adams in winter, and when i got to the bottom i realized i never ate my lunch! the water and calories in the 2 liters of atkins shakes kept me going all day. i got a kick out of that. drinking your lunch sure makes it easy. i still bring extra food in case i need it, usually low carb bars that are tasty and easy to eat. i find if stuff tastes good i eat it and drink it.

KayakDan
02-27-2006, 10:01 AM
Recently,we started drinking Gatorade on the trail,and it seems to help. I use roughly the same method as DougPaul.About every half hour we stop and drink. When Mrs KD says she had enough,I always tell her "fine,now one more drink".
It's amazing how fast dehydration will crash your energy in the winter,and you end up cold and tired. Same goes for eating. When I'm moving on the trail,I don't get hungry either. You have to just set a time or place and eat anyways to keep up your energy level.

DougPaul
02-27-2006, 12:34 PM
It's amazing how fast dehydration will crash your energy in the winter,and you end up cold and tired. Same goes for eating. When I'm moving on the trail,I don't get hungry either. You have to just set a time or place and eat anyways to keep up your energy level.
The same fuel and water that supplies the motor also supplies the heater...

Dehydration and low fuel are usually factors in hypothermia and frostbite. Two more reasons to stay fed and watered.

Doug

SAR-EMT40
02-27-2006, 01:15 PM
I can't remember the doctors name as I write this (brain burp) but he operates a medical tent and does studies on Denali as well as treat climbers. His comment on hypothermia is very revealing. He was quoted on one of the classes I had "he has never met someone who was hypothermic who also wasn't dehydrated". That should say something about hydration. Also, it is self feeding, a side effect of hypothermia because of the vasoconstriction is the core receives more blood. The kidneys recognize this as a fluid volume increase and treats it as such. Making you pee even more which dehydrates you even more. I have been told in at least one hypothermia class that it is not unusual in a hypothermia death to see an ice ball of pee around that area. I was told with avalanche rescues if they have an ice ball around them they probably died of hypothermia, if they have an ice mask then probably suffocation and neither they probably succumbed to the trauma on the ride down. Yes, I believe it is possible to have both.

One more comment to add. You cannot burn food as fuel without being hydrated. You can eat, but your body won't use it. At least that is what I was taught in cold weather training. I am talking about protein and fats. I am unsure about carbs and simple sugars.

Keith

SAR-EMT40
02-27-2006, 02:43 PM
Something I thought that everyone knew but I will mention it. The army spent a small fortune to find the perfect cold weather food to help its soldiers in the event they get hypothermic. They spent a great deal of money and a lot of time and they finally came up with the answer. It boiled down to this chemical formula that was suitably impressive but when other experts looked at it, it looked remarkably similar to another chemical makeup.

So, go down to the local food store and pick this hypothermia reconstituting powder up. You will find it at your local grocery store under the trade name Jello. Make sure you purchase the ones with sugar and you will have what the government spent a great deal of money and time researching and is still spending many dollars buying their own special form of. If the person is hypothermic and they can swallow then heat it up with water and allow them to sip/drink it. I always carry a box of Jello in the winter as part of my basic supply. It makes no difference if it is a day hike or overnight camping, I always carry it for hypothermia emergencies. It is also considered to be part of the basic rescue gear required to be carried by all searchers by NASAR, the National association of Search and Rescue.

Don't get me wrong. I don't begrudge the Army doing the research. I think thats great. I just wish they would have bitten the bullet and just went with Jello when they saw how close it was to what they wanted.

Keith

DougPaul
02-27-2006, 03:35 PM
I can't remember the doctors name as I write this (brain burp) but he operates a medical tent and does studies on Denali as well as treat climbers.
Peter Hackett?


One more comment to add. You cannot burn food as fuel without being hydrated. You can eat, but your body won't use it. At least that is what I was taught in cold weather training. I am talking about protein and fats. I am unsure about carbs and simple sugars.
The advice I have seen on survival is that if you are out of water, don't eat. Digestion consumes water. Don't remember any caveats on the kind of food.

Doug

SAR-EMT40
02-27-2006, 04:12 PM
Peter Hackett?

Thanks, yep.



The advice I have seen on survival is that if you are out of water, don't eat. Digestion consumes water. Don't remember any caveats on the kind of food.

You are correct but it takes lots less water to get energy (short term) from simple sugars and carbs. Eating things like proteins and fats can get you very sick when dehydrated. Another nail in your coffin in those conditions. Simple sugars and water are absorbed in the stomach. Fats and proteins have to go through the intestines. At least that was what I was taught.

Keith

forty8
02-27-2006, 04:16 PM
This is an excellent discussion! It's especially poignant to me having had a first winter hiking experience recently. One of the things that really struck me about it was how thirsty I was! I couldn't drink enough. I never get that thirsty in the summer. My reaction seems to be the opposite of what I should have expected. Weird.

Pete_Hickey
02-27-2006, 04:19 PM
You are correct but it takes lots less water to get energy (short term) from simple sugars and carbs. Even though it takes less water than it does for protiens and fats, it still requires water. If one is dehydrated and out of energy, one must weigh whether they would be better being more hydrated and less energy, or more dehydrated with more energy. In my case, I would let the remaining amount of time dictate. If I've only a short amount of time, I would eat.

A few weeks ago, I was in the unfortunate situation of having 6 hours to hike with no water. I decided not to eat at all, so that the food's digestion would not take away my water... That, and the rubber band trick...

SAR-EMT40
02-27-2006, 04:22 PM
I always carry a box of Jello in the winter as part of my basic supply.


One caveat I should mention. I don't just carry this in the winter. People, especially sick and/or injured people, can easily get hypothermic laying on the ground or being wet for extended periods of time during the spring and fall and yes, even during the summer. I actually carry a box all the time, I like strawberry best :D , not just in the winter.

Keith

SAR-EMT40
02-27-2006, 04:31 PM
A few weeks ago, I was in the unfortunate situation of having 6 hours to hike with no water. I decided not to eat at all, so that the food's digestion would not take away my water... That, and the rubber band trick...

I don't know what your specific circumstances were Pete and I am not second guessing but I am curious. If you knew you could move for those 6 hours you might have been better off eating snow and having some food. If you know you can move, eating snow probably wouldn't hurt you as much as being dehydrated. Again, this is me spitballing without knowing the specifics. Maybe no snow to eat or other concerns that I don't know about?

Also what rubber band trick? I have heard of things with pebbles and a couple of things with rubber bands but which one are you talking about? :confused:

Keith

erugs
02-27-2006, 05:07 PM
Do you have the citation? The only article I found was published in 2004, which seems a tad old.

I don't have the citation but will write to Professor Kenefick at UNH and get his input.

DougPaul
02-27-2006, 05:47 PM
You are correct but it takes lots less water to get energy (short term) from simple sugars and carbs. Eating things like proteins and fats can get you very sick when dehydrated. Another nail in your coffin in those conditions. Simple sugars and water are absorbed in the stomach. Fats and proteins have to go through the intestines. At least that was what I was taught.
My info was from the context of desert survival when you have run out of water.

I know that digestion of fats and proteins fails had high altitude and one has to stick to carbs. Presumably related to the oxygen requirements for digestion.

Doug

DougPaul
02-27-2006, 05:58 PM
A few weeks ago, I was in the unfortunate situation of having 6 hours to hike with no water. I decided not to eat at all, so that the food's digestion would not take away my water... That, and the rubber band trick...
Several years ago I did a 25mi, 1800 vert ft, 17.5 hr BC ski. I had stayed well hydrated and had been peeing regularly until I ran out of water 6-8 mi (~2+ hr) from the trailhead. Don't remember if I stopped eating, but I just kept skiing. (Streams were sufficiently frozen that dipping water out of one would have been difficult.) The only thing that I noticed was that I stopped peeing. However, I suspect that my range was limited.

I always have some extra water back at the car...

Doug

DougPaul
02-27-2006, 06:01 PM
One caveat I should mention. I don't just carry this in the winter. People, especially sick and/or injured people, can easily get hypothermic laying on the ground or being wet for extended periods of time during the spring and fall and yes, even during the summer. I actually carry a box all the time, I like strawberry best :D , not just in the winter.
Way back in winter school, hot jello was suggested as a good camping drink. Many found it too sweet for their tastes.

Nobody told us that there were studies backing it... :)

Doug

SAR-EMT40
02-27-2006, 10:58 PM
Many found it too sweet for their tastes.

I agree. I wouldn't/don't use it for everyday use. In fact I only carry it for medicinal purposes. :D

Keith

Zer0-G
02-28-2006, 05:19 PM
Good Thread....

Typically,only in the winter season, I drink full strength gatorade while backpacking. Not so much because I think it is good for me, actually it has way too much sugar for my purposes, but because it is tasty which encourages me to drink more. Additionally, to encourage drinking, I hang my bladder in a custom made bottle bag around my neck and inside my "jacket" and I clip the bite valve onto the strap connected to the bag inside of my "jacket". The bite valve is no more than a few inches away from my mouth for the whole trip and kept out of the freezing air and close to my Body heat. I find this very convenient and supports active hydration which is, as dicussed here, more challenging in the winter. Inside the jacket, nothing freezes and actually the fluid stays warmer and feels better going down than chilly fluids do. I do the same with my snacks. I keep them handy all day long in a pouch hanging inside my jacket. It keeps the food from freezing as well.

I find this approach is like dangling the carrot in front of the donkey and it supports me to get the fluids and solids I need to avoid bonking and to heighten my enjoyment.

You can pack all the water and food that is right and good for you no matter what it is, high tech or PB&J, but all too often I have seen people get dehydrated and go BONK because it is too inconvenient or too cold for them to stop, drop pack, get out the food/fluids eat/hydrate, pull on the pack and get walking again.

I have seen that play out WAY too many times. Never fails. There is always a few people on each trip I go on that fall into that trap.

My point is, make it as convenient as possible to get at your food/fluids/lifeline and you are way ahead of the curve.

DougPaul
02-28-2006, 06:16 PM
Typically,only in the winter season, I drink full strength gatorade while backpacking. Not so much because I think it is good for me, actually it has way too much sugar for my purposes, but because it is tasty which encourages me to drink more.
The maximum amount of sugar in electrolyte drinks is ~8% because more will give you a stomach ache. Many electrolye drinks contain this maximum amount and thus may give you a stomach ache if combined with some foods. For this reason, many dilute their electrolyte drinks.

While one can dilute an electolyte drink, it is hard to alter the ratio of components. If one is sweating heavily, one might want a full amount of electrolyte (primarily sodium and potassium) but less sugar. There is a recipe for homemade electolyte in the thread "long distance nutrition": http://www.vftt.org/forums/showthread.php?t=4914
If you use this recipe, you can alter the concentrations to suit your own needs.

In winter, I generally drink pure water, because I avoid sweating. If I sweat any significant amount, I add some electrolyte to my drink. (The fundamental purpose of the electrolyte drink is to replace the electrolytes lost in sweating.)

Doug

Kevin Rooney
02-28-2006, 06:25 PM
You will find it at your local grocery store under the trade name Jello.Keith -

If you've ever taken Wilderness First Aid from SOLO they also urge people to carry Jello, not only because when added to hot water it's something most hypothermic people will drink, but it can be a life-saver if someone is unconscious from diabetic shock. You can rub the Jello on their gums as a way of getting sugar into their system. Of course, you could use plain sugar also, but the thinking is you're more likely to have Jello than just the sugar.

In terms of hydration - I need 2 liters of something (water in summer, honey-sweetened herb tea in winter) on the average day hike. I make sure I've downed the first liter about 2/3's of the way up the summit. Occasionally, and this happens more in winter for the reasons noted above, I'll find I'm nearly to the summit and have not drunk the liter, so I'll stop and polish it off, whether I "feel" thirsty or not.

In my experience, you're far more likely to crash from too little water than too little food. So, if you bonk - make drinking upwards of a liter a priority, and then have something to eat. In about 30 minutes you'll feel quite rejuvenated.

Also - in terms of electrolyte replacement - there was a thread here several months ago about Morton Lite Salt, which contains 1/2 the sodium but twice the potassium of standard table salt. I now carry some in an old film container, and when I'm sweating alot I'll take a couple of pinches. I used to do the Gatorade thing, but can't bring myself to any longer.

hikerfast
02-28-2006, 06:42 PM
one thing i have started doing is starting to drink a quart of liquid about 10 minutes before i hit the trailhead and finishing it before i head up. usually water but others could drink whatever their pleasure. seems to make a huge difference for me. basicly its like adding another quart to your hiking days liquid immediately. real simple. the best method is to just bring another quart bottle and put it in the car when you head out, that way you make sure you do it each time.

DougPaul
02-28-2006, 08:15 PM
Also - in terms of electrolyte replacement - there was a thread here several months ago about Morton Lite Salt, which contains 1/2 the sodium but twice the potassium of standard table salt. I now carry some in an old film container, and when I'm sweating alot I'll take a couple of pinches. I used to do the Gatorade thing, but can't bring myself to any longer.
Close:
table salt is 100% sodium chloride
Morton LIte Salt: about 50% sodium chloride, 50% potassium chloride

Search on "Morton lite salt". It will bring up this thread plus 4 more. The 4 have info on electrolyte replacement, including my recipe for electrolyte drink.

Doug

Kevin Rooney
02-28-2006, 09:18 PM
Doug -

I think the FDA requires that table salt CONTAIN sodium cloride - around 98% if I recall, but that doesn't mean it doesn't contain other compounds as well, such as iodine, magnesium, calcium and anti-caking ingredients, most of which occur naturally. And, if you buy sea salt at the local coop, as we do, then there are probably other minerals as well.

It gets pretty confusing, especially when some research indicates that the potassium ingested in any way other than by food (bananas, spinach, orange juice, etc) simply isn't available for metabolism by the body. But, many of us still operate on the principle that "well, it can't hurt .." so we take our Gatorade, Morton Lite Salt, etc.

Zer0-G
02-28-2006, 10:26 PM
In winter, I generally drink pure water, because I avoid sweating. If I sweat any significant amount, I add some electrolyte to my drink. (The fundamental purpose of the electrolyte drink is to replace the electrolytes lost in sweating.)

Doug

Interesting. Avoid Sweating, regulation of body heat, Vapor barriers,
(I am a Vapor Barrier believer and I use them extensively and one of the benefits of that is the ability of the body to maintain a micro-climate that promotes less sweating as a result of the moisture being held close to the body as a result of the Vapor Barrier. etc....) climate control...all well and good. Sugar content, bellyaches. All very interesting and I'm just not that scientific. All I know is what is too sweet for my taste, but given certain conditions, what I am more willing to drink. :D And, that's the key. I got to get fluids in and for me PLENTY of them.

I have at least three liters of water/fluids on me when I start and I just drink drink drink, regardless of how much I sweat. Usually to the point where I eliminate copiously and clearly. :o

Even though there is, believe it or not a serious condition that is caused by over-hydration - it was explained to me in my SOLO WFA training - rare but possible. I would be hard pressed to drink that much. (gee, I forget the details...)

In the summertime, I usually supplement part of my water intake with GU-20 throughout the day. It is not as sweet as Gatorade and it is very effective. But in the winter, not feeling as thirsty as other times of year, I just got to have that extra taste to inspire me to drink even when I am not feeling thirsty. I guess it's a pshycological thing.

DougPaul
02-28-2006, 11:28 PM
I think the FDA requires that table salt CONTAIN sodium cloride - around 98% if I recall, but that doesn't mean it doesn't contain other compounds as well, such as iodine, magnesium, calcium and anti-caking ingredients, most of which occur naturally. And, if you buy sea salt at the local coop, as we do, then there are probably other minerals as well.
I was just trying to keep it simple and ignoring the impurities and minor ingredients.

My box of (iodized) salt says "salt, sodium silico aluminate, dextrose, potassium iodide".

My box of Morton's Lite Salt says "salt, potassium chloride, calcium silicate, magnesium carbonate, dextrose, potassium iodide". Must be iodized too.

My numbers were accurate within a few percent. :)

Doug

DougPaul
02-28-2006, 11:48 PM
Interesting. Avoid Sweating, regulation of body heat, Vapor barriers, (I am a Vapor Barrier believer and I use them extensively and one of the benefits of that is the ability of the body to maintain a micro-climate that promotes less sweating as a result of the moisture being held close to the body as a result of the Vapor Barrier. etc....) climate control...all well and good. Sugar content, bellyaches. All very interesting and I'm just not that scientific. All I know is what is too sweet for my taste, but given certain conditions, what I am more willing to drink. :D And, that's the key. I got to get fluids in and for me PLENTY of them.
Way back in winter school I was taught to run slightly cool to avoid sweating (avoids water loss, electrolyte loss, and getting one's insulation damp). One loses a lot of water (no electrolyte) through the heavy breathing in the dry air. And in theory, a VB should reduce water and electrolyte loss.

If the drink is too sweet, you can reduce the amount of sugar if you make your own. Or dilute a commercial drink and add a bit of Lite Salt.

If you do the search on "morton lite salt" and read the threads, many of the details are covered.


I have at least three liters of water/fluids on me when I start and I just drink drink drink, regardless of how much I sweat. Usually to the point where I eliminate copiously and clearly. :o
One of the rules of thumb is to make sure that you pee at least .5 to 1 liter and the color is light straw to clear. Sounds like you are getting there... You might also be drinking a bit more than necessary, but that is generally better than too little. 1.5 liters of water is generally enough for me in winter and up to 3 (occasionally 4) liters in summer.


In the summertime, I usually supplement part of my water intake with GU-20 throughout the day. It is not as sweet as Gatorade and it is very effective. But in the winter, not feeling as thirsty as other times of year, I just got to have that extra taste to inspire me to drink even when I am not feeling thirsty. I guess it's a pshycological thing.
Flavor often helps one to drink enough. I just eat relatively normal food--haven't gone in for these high-tech foods like GU.

Doug

Zer0-G
03-01-2006, 12:09 AM
Flavor often helps one to drink enough. I just eat relatively normal food--haven't gone in for these high-tech foods like GU.

Doug

There is a lot of good info in this thread. I should have been clearer. The GU-20 I referred to is actually a powder that mixes with water and is an electrolyte replacement type supplement. I don't go for the hi-tech foods either. Good old PB&J and Cheese and nuts etc is fine for me. ;)

rhihn
03-01-2006, 05:59 AM
The GU-20 I referred to is actually a powder that mixes with water and is an electrolyte replacement type supplement.

Do you know how this compares to Gatorade or other electrolyte replacement products (effectiveness, taste, cost, ease of use, etc.)?

Zer0-G
03-01-2006, 10:23 AM
Do you know how this compares to Gatorade or other electrolyte replacement products (effectiveness, taste, cost, ease of use, etc.)?

Well, to tell you the truth, I switched Gu20 from Diluted Gatorade upon a recommendation of a friend. Cytomax was also recommended.

I reviewed the labels of both Gatorade and Gu20 and decided, based on my experience and knowledge of the subject, which could stand quite a bit more research to become expert, that Gu20 was a better fit for me. It has way less sugar than Gatorade. I try to avoid excess sugar as much as possible.

I also visited the website and got some additional information. Which I took with a grain of salt, no pun intended. We all know about advertising claims.

http://www.gusports.com/html/gu2o.htm

DougPaul
03-01-2006, 07:21 PM
I reviewed the labels of both Gatorade and Gu20 and decided, based on my experience and knowledge of the subject, which could stand quite a bit more research to become expert, that Gu20 was a better fit for me. It has way less sugar than Gatorade. I try to avoid excess sugar as much as possible.

The basic purpose of the sugar in electrolyte drinks is to increase the speed of absorbtion of the water. It also has some fuel value (simple carbs).

Doug

JohnL
03-01-2006, 08:25 PM
Actually, I believe it is sodium that will speed the absorption of the water, not sugar. Excess sugar above about 8% will actually slow down the absorption.

JohnL

There are two main factors that affect the speed at which fluid from a drink gets into the body:

> the speed at which it is emptied from the stomach
> the rate at which it is absorbed through the walls of the small intestine
The higher the carbohydrate levels in a drink the slower the rate of stomach emptying. Isotonic drinks with a carbohydrate level of between 6 and 8% are emptied from the stomach at a rate similar to water. Electrolytes, especially sodium and potassium, in a drink will reduce urine output, enable the fluid to empty quickly from the stomach, promote absorption from the intestine and encourage fluid retention.

DougPaul
03-01-2006, 09:46 PM
Actually, I believe it is sodium that will speed the absorption of the water, not sugar. Excess sugar above about 8% will actually slow down the absorption.

JohnL

There are two main factors that affect the speed at which fluid from a drink gets into the body:

> the speed at which it is emptied from the stomach
> the rate at which it is absorbed through the walls of the small intestine
The higher the carbohydrate levels in a drink the slower the rate of stomach emptying. Isotonic drinks with a carbohydrate level of between 6 and 8% are emptied from the stomach at a rate similar to water. Electrolytes, especially sodium and potassium, in a drink will reduce urine output, enable the fluid to empty quickly from the stomach, promote absorption from the intestine and encourage fluid retention.
Do you have a credible reference for this info?

My reference is:
Kelly Cordes, "Liquid Lunch", Rock and Ice 102, Aug/Sept 2000, p 52.
Author info:
Kelly Cordes' exercise physiology masters's thesis at the
University of Montanna delt with hydration and thermoregulation.

According to my reference, the sugar concentration, up to a point, increases the absorbtion rate. Too much will slow it. The purpose of the the sodium and potassium is to replace that lost in sweat.

Doug

Lovetohike
03-01-2006, 10:23 PM
Great thread. One strong consideration that I don't think has been specificallyi mentioned, but is an important consideration primarily in warm weather extended exercise. That is hyponatremia, i.e. a condition that results from taking in too much water while exercising. This can result in a very serious dilution of electrolytes and severe problems (cardiac, etc.) It also is more prevalent, I think, in cases when just plain water is taken in, vs. water plus electolytes, but I think it can happen even when some electrolytes are taken in with the water. One guideline I read is that the average recommendation is around 28 oz. per hour, with variations depending on the weight of the person and exact conditions. And, many of these studies were done with marathon athletes, etc. However, an interesting finding was that the runners in the top group tended to hydrate o.k., and the runners in the middle and back tended more towards overhydration. Don't think it would be a problem at all in winter, where this thread started, but it has wandered into hydration in general and it's important to bring this aspect into consideration. Here (http://www.americansportsevents.com/pages/ResourceContent/HYDRATION.htm) is a one link I found that gives some pretty extensive detail on this issue. Very interesting discussion.

C.Tracy
03-02-2006, 04:56 PM
Wow, this is GREAT information. I for one can use it since I sweat fluid out just about as fast as I can put it in, and it does not matter what the temperature is sometimes. I like to drink a liter of water before I reach the trailhead, after that I normally go through 3 to 5 liters during the hike depending on its length and difficulty.Thanks for all the information.