I live in the foothills of the Sierra Nevada Mountains and every year people get lost and die in the winter. Normally they are not properly equipped and die from hypothermia. They drive to the snow in their nice warm car and go out to play on a sunny day, when it seems to be deceptively warm. They end up straying of the trails and night sneaks up on them. Without warm clothing, a way to start a fire, food or water, and no survival training, they succumb to hypothermia.
The human body temperature is usually maintained at a constant level of 97.7–99.5 °F. If a person is exposed to cold, and their internal mechanisms cannot replenish the heat that is being lost, the body’s core temperature falls and you are suffering from hypothermia.
Hypothermia can range from mild to severe. Mild hypothermia can be treated with warm drinks, warm clothing and getting warm. Moderate hypothermia is harder to treat. Recommended treatments include heating blankets and warmed intravenous fluids. In severe hypothermia, medical intervention is normally required to save the person’s life.
Hypothermia causes approximately 1500 deaths a year in the United States. Body heat is primarily generated in your muscle tissue, while it is lost through the skin (90%) and lungs (10%). Heat production may be increased 2 to 4 fold through muscle contractions.
A few years ago, a friend and some companions were caught in a severe blizzard in the High Sierra’s. They were forced to spend the night in a lean-to on a ledge. Now they were well dressed and had good equipment, but they were still in danger of hypothermia.
Because they could not get up and move around, they used isometric exercises to help raise their body temperature. An isometric exercise is a form of exercise involving the static contraction of a muscle without any visible movement in the angle of the joint. When you create the tension in your muscles, it creates body heat. Tighten your muscles and hold them tight for a short period of time, maybe 30 seconds. The bigger the muscles the more heat. Be careful not to generate any type of a sweat. My friend, who taught for the US Marine Corp Cold Weather School at Pickle Meadows, said that this helped them stay warmer throughout the night.
Appropriate clothing helps to prevent hypothermia. Synthetic and wool fabrics are superior to cotton as they provide better insulation when wet and dry. Some synthetic fabrics, such as polypropylene and polyester, are used in clothing that is designed to wick perspiration away from the body. Examples would be moisture-wicking undergarments. Clothing should be loose fitting, as tight clothing reduces the circulation of warm blood. See my previous post Hypothermia, How to Dress to Avoid It.
I want to make one correction to my previous post. In it I mentioned that you could lose up to 50% of your body heat from your head and neck. I have since found out that this is incorrect. Covering the head is effective, but no more effective than covering any other part of the body.
Remember that wet rainy weather with temperatures above freezing in the 40 and 50s can be just a dangerous as colder temperatures.
Stay well dressed and warm and carry survival gear.