We are always preaching about staying hydrated during the Selection course as well as in your preparation train up beforehand. And practicing proper hydration has to be practiced during the Selection course, regardless of the season or you will most assuredly fail.

The military is unlike almost every other profession because we work outside, regardless of how hot and humid it is. And in Special Operations, we saddle our troops down with about 100 pounds of “lightweight gear” to boot.

Did you know that hydration just one percent below optimal, can affect mood, make it more difficult to concentrate, and produce a headache? And it goes without saying that if you become dehydrated by even relatively small percentages of your body weight, your physical performance will also decline dramatically.

Dehydration goes hand in hand with contracting a heat illness, like heat cramps, heat exhaustion or the potentially fatal heat stroke. But first, we get to the basics. What exactly is dehydration and how does one get it?

Dehydration occurs when more water is being lost by your body than is being put in. Our bodies get dehydrated through urine and sweat, and through respiration, we’re constantly using and losing water. Even while sleeping, we will use water as it passes out of our system with every breath we exhale.

Brain Function and Dehydration:

Our brains are made up of about 75 percent water, and even the slightest bit of dehydration will affect the way it functions. First, it alters the way we think and feel as our circulation begins to slow down. This slows blood flow, which means less oxygen is traveling to all parts of the body, including our brain.

If the condition begins to worsen, our cognitive function is further affected, leading to delirium. If anyone has seen the documentary on SFAS called “Two Weeks in Hell” where a candidate during the Log PT smoke session got dehydrated and began to get delirious. The cadre medic pulled him from the pit and then asked him if he knew where he was. The candidate hesitated and then answered, “Hashbrowns?” as a question. Thankfully, rest and I.V. fluids will soon have the affected person as good as new.

Severe dehydration, however,  can cause unconsciousness and even cause the unlucky individual to lapse into a  coma, and then finally leading to death.

How Much Water Is Enough:

That’s a good question.  And there isn’t a straight textbook answer as everyone’s bodies are different. And other factors come into play as well such as Age, General Health, Level of Activity and Climate can all affect the amount of water that is needed to keep yourself hydrated.

The Army and most medical professionals will tell you not to use thirst as a gauge of hydration because, by the time you are thirsty, you’re already dehydrated enough to have it affect your mood and brain function.

Most medical professionals say to the safe amount we should all be drinking is eight to ten eight-ounce glasses of water per day. More on hot days, and increase the amount depending upon the greater the physical activity.

While we all consume sports drinks, and they will help you not only rehydrate but to replenish electrolyte loss, they aren’t really necessary. As long as we eat everything in our meals, we will refuel our bodies and electrolyte levels just fine. And those tend to have a bunch of sugar, and like anything else, moderation is the key

And as a reminder, never put sports drinks in a Camelbak hydration system or a canteen as they’ll foster bacteria growth.

Acclimatization Is Very Necessary:

It used to be thought of as an old wives tale that people could acclimatize to the heat. But it is a fact. And if you are attending Selection in the early fall or early spring months, the weather can be quite hot in the southern United States. Getting acclimatized takes about two weeks with a couple of hours of exposure per day, but most of it can be accomplished in as little as five-to-seven days.

If at all possible, if you’re traveling from a cooler climate to the south for Selection in the warmer months, if at all possible, try to arrive early and begin your acclimatization.

However, something to keep in mind is that, even in the winter months, hydration is just as important. Many soldiers will not drink as much water in the winter as they do in the summer and it can cause them just as easily to dehydrate. And the cold can suppress your thirst.

So remember, during Selection, especially on the timed ruck gates, or during Land Navigation, ensure that you’re consistently sipping from your hydration systems. Just becoming slightly dehydrated can cause you to make some bad decisions and you don’t need that while out on the course. Drink as if your life depends on it…because it does.

Photo: DVIDS

Originally published on Special Operations.com