Body Climate Control
From WildWiki
Contents |
Body Climate Control- Staying Warm, Dry, Hydrated, and Well-Fed
Many students think that being damp and cold is normal when you are living in the wilderness. Early in the course, show them they can stay comfortable in the most challenging weather conditions simply by dressing, staying properly hydrated, eating balanced meals, and monitoring your activity levels properly. A student who is warm, dry, hydrated, and well-fed is going to be a safer expedition member, a more attentive learner, and a more enjoyable companion.
Educational Goals
By the end of the course, students must demonstrate the ability to stay healthy and comfortable while living and traveling in the wilderness. This requires a practical understanding of the effects of clothing, layering, nutrition, hydration, and physical activity on personal comfort. Outdoor leaders must be able to take care of themselves and stressful situations, and still have enough energy left to look after others. You should cover these topics early in the course and help students see the connections between hydration, nutrition, and staying warm and dry. Give them the reasons WHY they may feel cold or uncomfortable and then the tools for HOW they can take care of themselves and their teammates. This involves three main skill areas: clothing and layering, nutrition, and hydration.
Key points
Heat Production
Under normal conditions, our body produces heat through muscular activity and basic metabolism. A healthy body that is well-nourished, hydrated and reasonably insulated maintains its temperature at approximately 98.7 degrees f. When we get chilled, we start shivering. Shivering is a involuntary response intended to generate heat quickly through muscular twitching.
Heat Loss
Heat flows from warm objects to cold via radiation, convection, conduction and evaporation. Radiation is the movement of heat in the form of particles or waves, similar to light or a radio wave. All objects radiate heat. Warmer objects radiate more than cooler ones. Since we are often the warmest object in an area, we have a net heat loss to the environment. Head, hands, and feet have many blood vessels close to the skin which increases their potential for radiant heat exchange. When our bodies are cooler than the surrounding objects, they pick up radiant heat through the same mechanisms.
Convection occurs when a moving medium, such as water or wind, sweeps away an object’s pocket of radiant heat. This is how you loose heat when you stand in a cold stream or a cool breeze.
Conduction is the direct transfer of heat from a warm object to a cool one. A warm butt sitting on a cold rock experiences conduction. Some objects, such as metal, conduct heat better than others, like ensolite.
Evaporation is the process of changing a liquid into vapor. It takes heat for this transformation to occur, so evaporating sweat cools your body. This is why a wet bandanna on your head, or dipping your hands or feet into water feels so good on a hot day. Dry climates help evaporation occur quickly; wet climates hinder evaporation.
Dressing For The Cold
Cotton Clothing works well in hot climates because it holds moisture against the skin, promotes evaporation, and accelerates heat loss. For these same reasons, you should not wear cotton on cold or wet days.
Modern fibers and layering systems provide lightweight, functional clothing that can keep you warm and dry if used properly. Layering clothes creates dead air spaces which trap warm air and provide insulation. Clothes made from wool, pile or polarfleece have hollow fibers that create air spaces that trap air. Breathable wind gear prevents heat loss from convection. Polypropylene underwear wicks moisture away from your skin before and cooling evaporation takes place. Hats and gloves also provide a great deal of warmth by minimizing radiant heat loss.
Rain gear helps keep other layers dry but since it is non-breathable, you get soaked with sweat if you exercise in it. When temperatures are mild, you will often be more comfortable hiking in polypro and wind gear on rainy days. When it is cold and rainy go ahead and hike in rain gear with a light layer of polypro underneath to minimize sweating. In either case, once you get to camp, change into dry clothes before you cool down.
Staying Warm
helpful hints for your students (and you!)'
Staying warm takes work, but getting rewarmed takes a lot of work. When the wind is howling through your tent, it is difficult to drag yourself outside to start the stove and cook a meal or get more water, but staying properly hydrated and healthy takes a little bit of knowledge and a lot of self discipline.
1) Layers allow for more flexibility throughout the day
2) Start cold. That is, you should be border line uncomfortably cold prior to physical activity (like beginning a hike or paddle day). Your body will warm up as you exercise- if you bundle up in the am, you’ll be sweating out those layers in about 25 minutes.
3) The simplest way to manage your body temp is to manage your level of activity. If you are too warm, slow down. If you are cold, speed up. This minimizes a lot of starting and stopping to layer and de-layer.
4) Food and water are critical to body temp- see discussion on nutrition and dehydration below.
5) Keep a “bomb-proof” in camp layer that stays dry. Put it in your sleeping bag and only pull it out when you are in camp and can be sure that you can stay dry. Do the same thing with one pair of socks.
6) Take advantage of sunny warm days by drying out every piece of clothing you can.
7) You can dry out socks by sleeping with them under your kidneys. You can also wear a “sock bra” while you are hiking or paddling to dry off socks with your body heat.
8) Drinking a “super cocoa” before bed- cocoa plus butter- will help keep the fire stoked during cold nights.
9) Change out of trail clothes for sleeping- even if they don’t feel wet, they have retained moisture that will draw heat from your body. A light polypro layer for sleeping that stays dry all the time works well.
10) Boiling water and putting it in a nalgene to sleep with keeps you warm.
11) Get into your sleeping bag warm by doing jumping jacks or sit ups or some other form of activity. Remember, your bag does not get you warm, it keeps what warmth you bring into it there.
12) Hats and hot drinks are miracle workers for keeping warm.
Nutrition and Hydration
Nutrition and hydration play essential roles in keeping us warm. The calories our bodies burn come from the food we eat. Carbohydrates burn quickly. Fats, on the other hand, take up to three hours to kick in, but they provide twice as much energy per gram as carbohydrates. When staying warm is a struggle, eating a balance of the two will provide you with the energy you need.
In cold weather, breakfast is critical to maintaining energy and warmth over the course of the day. Eat a power breakfast containing lots of carbo’s. eat fats at bedtime to have fuel early in the morning when the carbo’s have metabolized. When the conditions are harsh, a proven strategy is to snack all day long and through the night. Remember this mantra: lunch starts right after breakfast and ends right before dinner. Snacking is preferable to a long, drawn-out lunch which puts students into food coma and is less efficient for traveling.
Carbo-loading
If the word “carbohydrate” were Latin it would mean efficient, readily available source of energy. Body fuel. To allow your body to function at the high level you’ll be asking of your diet will need to be 60% carbs. Pasta, grains, potatoes, cracker mixes, fruit drinks fruits, cereals and cocoa are great source of these little beauties. Carbs come in a couple of forms, and each has a different function. Simple sugars are sweet foods and drinks that are absorbed easily into the blood stream and provide a quick start, but one that doesn’t last long. Another form of carbohydrates is complex carbs. This variety takes longer to break down, but also lasts longer to get you through the long haul. Grains, breads, pastas, potatoes, and legumes fit into this group
Fats are your Friends
Fat is not a four letter word. In fact, fats are an essential nutrient in your diet – as essential to good health as protein and carbos. Fats are actually the most concentrated form of energy around, having twice the energy of carbohydrates! Fats are not only a great source of energy and keep your skin healthy, they keep you warm! Fats are important in the function and structure of body tissue as well. This is not to say that all types of fats and lots of fats are good health for a nonactive diet. However, while you are on trail, 25-30% of your diet should be composed of fats. This sounds like a lot, but considering the rate at which your body is moving and your metabolism is ticking, you’ll need all 25%. The easiest and best way to add fat to your expedition diet is through margarine, oil, nuts and nut butters and cheese. Not only do these items give you the fat you need but they also add a whole lot of taste to pastas and breads. In short, your body needs fat. Don’t skip in this area of your diet. Keep in mind that 95% of the fat you ingest will digest and the fats you can easily take in a ration.
Proteins
Protein is the basic material of every body cell. It is the creature that rebuilds tissue. Protein is also a component of enzymes and hormone, which play an important role in metabolism and digestion. Everything you are is protein: hair nails skin and blood. At least 15% of your diet should be made up of proteins. You will find, however, that many foods you think of as being high in protein (milk, eggs, meat) are not practical to take as part of a ration. Therefore, substitutes must be found – powdered milk, for example.
Keep in mind, too, that there are two many types of proteins: complete and incomplete. Complete proteins include milk, fish, egg, and cheese and they are primarily found in animal foods. On the other hand, incomplete proteins are more abundant in a ration-type diet: corn, grains, legumes, nuts, peanuts, and other plant foods. When combined in a certain manner, these incomplete proteins suddenly become complete to give you what you need. For example, beans and rice, pea soup served with corn bread, bread with peanut butter.
Hydration
Hydration is integral to heat production. A well-hydrated body utilizes its food more efficiently and has better circulation. Cold temperatures increase urinary output, thus accelerating dehydration. Drink 3-4 qts. per day normally, 5-6 qts. in the cold or at altitude. Your urine will be clear and copious if you are well hydrated.
As the American Heart Association so eloquently puts it, “Water is essential for survival.” As we know, they tend to be right. Yes, folks, hydrate. Water is not critical for nutrition, it also helps to cleanse your body, digest and regulate body temperature and keep cells healthy. A person can go for several days without food but the length of time without water is much shorter. Your body is 50-70% water, and you need to replenish that constantly.
The AHA recommends drinking 6-8 glasses of water per day, and that’s if you’re not exercising. Your body needs that much and more once your really active. Ideally, you should drink at least 4 quarts of water per day enough to keep your urine clear and copious. You will find that water will cure many of your ills – dizziness when you stand up, sore muscles, low motivation, etc.
Teaching Considerations
Often conditions dictate that you cover this topic on the first day of the course. Start with simple facts, then expand on them until all expedition members are able to take care of their personal comfort. You can integrate the topic into lessons on cooking, hydration, trail technique, cold injury awareness, and leadership.
Students learn a great deal by watching their instructors manage their own personal climate control. An inappropriately dressed instructor should not be surprised when his students follow his example. Model impeccable standards. Put on an extra layer the minute you stop for a break in the trail. Carry a hot drink with you when you make camp visits. Take off your cotton t-shirt when it starts to rain. Your students learn best by mimicking your actions.
Resources Peters, E. Mountaineering: The Freedom of the Hills. 5th ed, 1992, pp65-78 Forgey, WM. Death by Exposure, hypothermia, 1985, ICS Books, pp33-35, 8-11
