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Having completed another chilly open-water swim and with the approach of winter, I decided to write about the effects of hypothermia. Hypothermia is defined as a decrease in body temperature, significantly below 98.6 degrees F, upon exposure to a cold environment. The warning signs of hypothermia include: slurred speech, loss of coordination of the hands, inability to walk and mental confusion.
The warning signs of hypothermia reflect the body's efforts to protect itself from the cold. At first the brain sends signals to the skin to close down circulation. This is because the blood returning from the skin to the internal organs is cold and will chill the inner body. It is re-warmed by passing next to arteries which are bringing warm blood away from the body's center. This works amazingly well in some individuals. Normal body temperatures have been detected in English Channel swimmers whose skin temperatures had dropped to 59 degrees F. If the body continues to cool, it shuts down blood circulation to the arms and legs.
When cold, the body attempts to generate heat by shivering which is the rapid contraction and relaxation of the muscles. More than half of the energy produced by shivering is usable heat. Conserving generated heat is done through natural insulation. Muscle, skin, and fascia provide 50 percent of the body's insulation; the other 50 percent is provided by body fat. Senior citizens are more vulnerable to hypothermia since their internal thermostats operate less efficiently.
To protect yourself from hypothermia it is important to dress properly, eat heartily and train for the cold. Cold is felt first in the fingers, toes and ears. Items which protect these areas, such as an insulated cap, conserve body heat. The best foods for staying warm are carbohydrates and fat. Up to 60 percent of the calories you eat are used to heat the body; the remaining 40 percent fuel the muscles. Avoid drinking alcohol - it dulls the body's reaction to the cold. You can train your body to tolerate cold to some extent. Repeated exposure to the cold eventually acclimatizes the body by training it to produce more heat.
The following is a listing of the effects of various drops in body temperature.
The treatment for hypothermia is gradual rewarming. This should be done using a warm bath, hot water bottles and blankets, or another human body. Good luck, be careful and enjoy your winter training.
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