Hydration

Does someone have a reference regarding the hydration requirements of a person hiking, hunting, nordic skiing?

How much water do you need per day.

In what enviroment/temerature?

Let's use 3000 feet, dry conditions at 68 degrees F.

A solid reference would be appreciated.

the united states army field manual, known for dealing with the needs of large groups of people:
here.

You are asking for three very different types of activity. Nordic skiing is a very aerobic activity. Hiking can be considered aerobic but it is mostly a low impact activity that affects the muscular/skeletal systems before the heart/lungs. (This does not consider the individual fitness, amount of weight being carried, temperature, altitude and elevation.) Hunting also has a wide variance of aerobic potential but is is mostly a walking, stalking, sitting environment. Depending on the animal, birds would add very little to effort but hauling a deer would be quite taxing physically.

All this activity also does not include how each individuals body processes exertion, heat and sweat rates.

Still with me? So all this being said as a general rule of thumb I recommend drinking between 4-6oz of water every hour awake. This is not guzzling a liter every 4 hours, this is consistent imbibing every hour. This is also in line with most philosophy of drinking 12 oz of water 6x per day or 8oz of water 8x per day. With increases in consistent activity, nordic skiing by example, a person could/probably should be looking at closer to 1 liter per hour.

It is not advisable to 'pound' water or guzzle a liter at a time, regardless of activity. Consistent sipping will allow the kidneys to flush toxins out of the blood and keep your core temperature lower.

There is no one answer.

Things that factor in:
-physical condition
-activity type and duration
-temperature
-humidity
-general health
-what you eat
-medication
-injury

You should be peeing clear and colorless. You should do so several times a day. That is the closest there is to "one answer".

@IronRaven

Well put. I suppose I will also through out the cliche, "if your thirsty its too late."

Back in the 80s a few military organizations went to a [censored]/drink on demand standard in the field during hot weather. August in Camp Blanding, pushing 100F, no wind, 100% humidity can eat your lunch.

At the first sign of dragging, other times entirely randomly, someone would tell you to take a leak. If you couldn't produce a good stream you were told to drink a canteen full of water. Other times they would just tell you to drink, just making sure.

Mostly it was the macho guys who were too tough to drink, and a few country boys who think 'you sweat less if you don't drink', as if that was a good thing, that had issues. They were usually the ones who got 'bear caught' and fell out. It can come up fast. One minute I was talking to a guy who looked a bit winded and the next he was on the ground having convulsions. Serious enough a situation that we flew him out by helicopter packed in ice.

We had had problems but after that it was [censored]/drink on demand.

Cold weather doesn't drop the bodies from dehydration as quickly. It kind of sneaks up on people. Cold seems to suppress the feelings of thirst. Under such conditions dehydration can make you feel colder, make you more prone to frostbite and generally decrease physical and mental performance. Having a few people who had to be surgically 'opened up' with a glorified apple corer due to 'fecal impaction' caused by dehydration, described as the worse case of constipation imaginable, caused a greater emphasis to be placed on proper hydration.

Good times.

I would peacefully disagree with your comment on Cold weather not causing dehydration as quickly. I may be parsing your words or thoughts, but coldness is a false sense of hydration security.

Perhaps because people don't stay out in the elements as long in cold or the activities are not as vigorous but people get dehydrated at alarming rates because of this false sense. A cold wind will absolutely dehydrate a person.

As to to the drink on demand in the military. i remember those times very well. A deep booming voice saying loudly, "HYDRATE".

I use that with my son to this day.

Dehydration can also contribute to hypothermia. If it hadn't happened to me, it wouldn't have occurred to me. Then I looked it up, and guess what?!

"Cold weather dehydration can lead to total body core cooling."
http://www.thefarm.org/charities/i4at/surv/cold.htm

Sue

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.

The usual places to find something so specific are personal training clinics or specialized medical/ rehab facilities for endurance athletes.

There are several variance as you state, but my primary endurance activities are cycling and road running which is how the test would be performed. This first test is a baseline for off season training. Another would be done at peak season training for comparison. I've also tried to set it up for the baseline to be done in winter and the peak to be done in the desert summer. Covering most of my bases.