I think a lot of people don't understand how dry cold air is.
Those big clouds of vapour you see every time you breath out is water you are losing out of your lungs.

+1 on most of the above. Water is not optional - your body and mind does not function properly, and you freeze much faster without fluid. Peeing color is the best indicator...


Poor ydration severly limits your ability to fight off cold. A hot drink is best if you are cold, but a cold drink is infinitely better than no drink. You may want to adjust your drinking cold water into periods with surplus heat (i.e. high activity, or when moving). Eating snow is not recommended - it requires calories to melt, and burning those calories requires more water than you gain. (You CAN eat SOME snow in periods of high activity -- but you will NOT be able to gain much fluid this way. Think of it more as an extra "cooling device").


Oh, and one point about nordic skiing: There is no law that states that nordic skiing needs to be an aerobic activity. I do both a "hiking skiing", which is at a leisurely, low aerobic pace and as a training exercise I ski as fast as I can (high intensity aerobic). Depends on what kind of trip I do, whom I go with and what our purpose is. Also, I ski with heavier gear at my "hiking skiing" trips. Going downhill with telemark turns is just too much fun.... Using skis that are somewhere inbetween "nordic racing skis" and slalom, we call them "mountain skis" as you can use them skiing off tracks in the mountains. I reserve the thin, light ultra-fast-track running "nordic skis" for aerobic training purposes only.

Definitely true. I have had occasion ro review field notes I had taken in a severely dehydrated state and it was clear that my judgment, especially my estimates of distance, was shutting down... Just when you need to think clearly.

If urine is anything other than clear, it is time to take in more fluids. (if possible)

Generally true and a valuable guideline it shouldn't be applied dogmatically. Certain drugs, vitamins, and some foods, can cause urine to be more colorful and seem to indicate dehydration when no such condition exists.

Outdoor_Quest, I'm just curious. Are you asking this question from a "How much water should I plan to take along?" perspective, or more of a "How much should I be drinking during this activity?" perspective? We've had some good answers to the latter question, but the former question is very difficult to answer because of all of the variables involved.

The best answer is probably just doing a personal experiment yourself in the conditions you're interested in, observing how much you drink and whether you think it was adequate or not, and making a decision based on that experiment. Some people are apparently part-camels while others seem to run out of water while the car is still in sight.

Interestingly enough, I am trying to schedule a sweat output test to see my exact rates under exertion.

I am getting a lot of feedback, thank you.

I will check that Army field manual.

To answer Arney's question, I am looking at how much should a
person drink in one day.

Personally, I take a full camel back bladder on my outings and based on the feed back above, I probably don't drink enough while hiking. This was an issue in Glacier Park last summer when I drank the bladder down on a 8 mile hike. I was able to replenish quickly but, still, should probably have done so more frequently.

Interesting. How are you going to measure your water loss? Based on how much you drink?

Personally, I've tried doing this experiment a number of times and I just weigh myself before and after some activity. The difference in weight, minus an adjustment for water I drink along the way, gives me a decent idea of how much I lost and how much I might still be short, even after drinking.

One thing about cold weather activity that irks me and might skew your experiment (at least it does for me) is thermal diuresis--i.e. the diuretic effect of the cold. Within 20 minutes of going out into the cold from a warm place, I suddenly have a really full bladder that I need to pee away. It's not THAT critical, but you will overestimate your water loss during some activity if you weigh yourself before the thermal diuresis kicks in when you first go outside. I mean, you really are losing that water, but it's not actually activity-related water loss.

@Arney.

The sweat rate test is not self administered. Its done in a clinical setting under specific conditions. It will tell you your loss rates and can also tell you specific minerals that are sweated out.

I will use the information to adjust my water and electrolyte intake.

I do the weight pre/post workout technique as often as I can. Even bringing a scale in my car to my outdoor workouts every now and then.

Oh wow, you're going so far as getting your sweat content analyzed? That's pretty darn cool. What kind of facility are you getting this performed at? Doesn't sound like something you'd typically get done at the local hospital.

Even so, it's still a simulated environment. And sweat composition varies over time for various reasons, like from off-season into peak shape, or from cooler months into hotter months, so it's still an approximation. But very interesting.