Dressing For Outdoor Activities And Adequate Water Intake
This short document will give you basic guidelines on choosing clothes for day hikes in hot,humid weather.
We begin with some basic knowledge of how the body responds to vigorous activity.
Exercise produces heat. The human body must stay within about a degree of normal or it will suffer damage from overheating. This is why a high fever is so serious.
The brain cannot tolerate 103 degrees for long without serious damage.
The human body has two principal methods of controlling excessive heat and coolingitself: convective heat loss and evaporative heat loss.
Convective heat loss is the cooling you feel when a breeze hits you.
Evaporative heat loss is the cooling you get from sweat evaporating from your skin.
You might be wondering what this has to do with the proper clothes but it will become clear in a minute.
During a hike you cannot really control convective cooling. Either there is a breeze orthere is not.
But you can control evaporative cooling and it is connected to your water intake and yourclothes.
As you hike on a hot day, your body heats up and begins to sweat to cool itself. Obviouslyyou are losing water and you've probably noticed other minerals too, that's why sweat is salty.
Now, as our bodies are 80% water, losing water is not a good thing.
You must replace this water regularly or the body will lose its ability to cool itself as well as function in general.
Water is needed for almost every important physiological function of the body, from burning energy- the energy you use during the hike-, to eliminating waste and toxins- yes, pooping and peeing-, to digesting the food you use to create the energy in the first place.
So you must drink water to replace what you lose through sweating, and you must ensure that the sweat on your skin evaporates so the evaporative process cools you.
How much water must you drink during a hike?
This varies from person to person, but it does not vary much.
During a hot, humid, windless day (no convective cooling) you will need about 1/2 gallon or 2 liters of water for every five miles. Yup, that's a lot. Nope, you shouldn't try to tough it out.
Drink the water and enjoy the hike.
You can also use time as your measure. You should drink 10-12 oz., or 300-350 mL every 20
30 minutes. It's better to spread out the drinking instead of waiting to drink 16oz./500mLall at once. The way to do that is to take a sip or two every time you stop for a break, to take a picture, to look at the view, or look at the map.
How should you carry your water?
During a long day hike you might need up to 1 gallon/4 liters of water. You will probably be able to refill along the way. Here is my only recommendation for anything specialized.
Get yourself a Nalgene bottle or two. They are almost indestructible, can survive a fall
onto rocks or pavement, have gradations marked on the side in ounces and liters so you know how much you’re drinking, and are just great little pieces of gear. You’ll be surprised by how quickly you’ll become irrationally attached to your Nalgene bottle and its color.
They come in lots of sizes. A good option would be a 1 liter/32 oz. bottle and a smaller
.5 Liter/16 oz. one you can carry comfortably in your hand. I like to carry two of the
1 Liter/32 oz. bottles. The big one costs about $9 at EMS, REI, Campmor, Ramsey Outdoor, or any other sporting goods or outdoor goods store.
They're worth it.
Certainly you can use cycling water bottles, other sports bottles, or the plastic bottles water usually comes in.
How do you know if you are drinking enough water?
As it says in one respected backpacking guide, your urine should be "clear and copious".
You've probably noticed that when you drink a lot of water your urine is clear. Yellow urineis a sign that you are a little low on water. It's not life-threatening, just a sign.
Also, don't wait until you are thirsty to drink. Drink BEFORE you are thirsty. A good ruleis to take a few good sips every time you stop to take a picture, enjoy the view, or take abreak.
You should also drink lots of water in the days before the hike. If your urine is clear and copious on the morning of the hike, before you begin, you're off to a good start.
Of course, if you’re drinking a lot of water you’ll probably have to pee while on the trail and people sometimes hold it in for hygienic reasons (Dirty hands). There is an easy solution: Bring some of that no-water-needed hand sanitizer.
Take a pee, sanitize your hands, and Bob’s yer uncle.
If the hike will last longer than three hours, bring lunch. Anyone who’s been on a hike longer than three hours can tell you how hungry walking on hills can make you.
It's also good to have some snacks during the hike. Choose according to taste. Energy bars,chocolate and nut candy bars like Snickers, GORP (Good Ol' Raisins and Peanuts), granolabars, peanut butter and jelly sandwiches, etc. You want a little bit of fat, a little bit of protein, and some carbs as well.
Snack like a chipmunk: lot's of little bites.
Now we get to the clothes.
So, you're drinking enough water to replace what you're losing through sweat and now you wantyour clothes to soak up the sweat and let it evaporate. Cotton is not the best material forthis. It's not horribly bad but it's not the best.
If the cotton is thick it will absorb lots of fluid but will take a while to dry through evaporation. So until it evaporates it's keeping that warm fluid right next to your skin.
If the cotton is thin, it quickly gets saturated and stops absorbing the sweat so the sweat stays right ON your skin.
What is the solution? Most experts recommend t-shirts and shirts made of polyester and/or nylon. If you have swim shorts you've probably noticed how fast they dry. That's because they're almost always polyester or nylon or a blend. You might have heard of fancyfabrics called Cool-Max, MTS2, Duofold or Capilene. These are just special polyester fibers made by different companies. Supposedly they move the sweat away from your body more quickly and let it evaporate more quickly. They are pricey but unnecessary for beginners. A simple polyester outdoor t-shirt from any local outdoor gear/clothes shop will do. An even less expensive option is a cotton/polyester blend t-shirt or polo style shirt or button-down shirt. 85% poly-15% cotton is a common blend and works very well. You don't need to spend a lot if you’re just getting started.
It’s not that the “technical” clothes aren’t worth the money. You just have to decide if they’re worth it to you or not for three long day hikes a month.
For bottoms, shorts in cotton, polyester, or nylon are a good choice. Any swim trunks are really good. You can jump in a river or lake during the hike, get out, be dry in a flash, and continue walking. The quick drying also applies to nylon and polyester tops.
If you must wear trousers, you can get polyester and/or nylon hiking pants but they're at least forty dollars if they're not on sale.
We recommend against hiking in jeans or even shorts made of heavy cotton in hot, humid weather. Rain can hit you at any time and probably all of us know how uncomfortable wet jeans are. Lightweight cotton/poly blend chinos are excellent. If you must wear 100% cotton, make sure it’s a lighter weight.
For sockswe recommend you stay away from 100% cotton. It gets wet with sweat, stays wet, keeps the skin wet, and can cause ablister. Nothing ruins more hikes than painful blisters. Polyester/cotton or nylon/cottonblends are good. Lightweight wool (like the Smartwool brand), wool/cotton, or wool/polyester blends are good too.
Some people find even lightweight wool too warm but many like how dry it keeps your feet. Let your taste and comfortbe your guide.
You don't need fancy boots or hiking shoes. A good pair of running shoes, trail runners, or sturdy walking shoes are all you need.
A hat or baseball cap to give your eyes a little shade is always nice. Even a simple tennis visor helps. Sunglasses can't hurt. If you are wearing short sleeves or shorts and you burn easily, don't forget your sunscreen.
Thanks to Robert, Renya, Francisco, Emily, and Paradox for their suggestions and critiques.