How does your body adapt to a cold-weather environment? There are primarily three mechanisms to avoid excessive cooling:
- Shivering--the rapid, involuntary cycle of muscular contractions and relaxation
- Non-shivering thermogenesis--the sympathetic nervous system stimulates your metabolism
- Peripheral vasoconstriction--smooth muscle contraction around the arterioles reduces blood flow to your skin
- Dehydration--occurs due to a decreased water level within the body
Treatment: drink water
- Frostbite--occurs as a result of the extremities being exposed to freezing temperature for too long
Treatment: put hands under arm pits, remove and/or keep cold, damp material away from skin
- Hypothermia--occurs as a result of being submerged in cold water for too long
Treatment: go to a warm area, remove wet clothing, dress in warm clothing and wrap in a blanket
How does your body adapt to a hot-weather environment? There are primarily four mechanisms to avoid excessive heating:
- Conduction--10 to 20% heat transfer via direct molecular contact
- Convection--10 to 20% heat transfer via the motion of gas and liquid across your skin surface
- Radiation--60% heat transfer via direct emittance of infrared rays occurs primarily during rest
- Evaporation--20% heat transfer during rest but up to 80% heat transfer during exercise via sweat from your skin being converted from liquid to vapor. In a high-humidity environment, evaporation is limited and your sweaty skin has less of a cooling effect. In a low-humidity environment, evaporation is increased and your skin tends to remain dry for more of a cooling effect.
- Heat cramps--occur as a result of an excessive loss of electrolytes in conjunction with dehydration.
Treatment: go to a shady area, drink a saline and/or an electrolytic solution, stretch, ice massage
- Heat exhaustion--occurs as a result of an excessive loss of water via sweating from the skin.
Treatment: go to a shady area, remove clothing, elevate feet, remove clothing, wrap in a wet towel or sheet, drink cold fluid and/or saline solution
- Heat stroke--occurs as a result of an excessive rise in internal body temperature (i.e., > 104 degrees Fahrenheit).
Treatment: go to a shady area, remove clothing, wrap in a wet towel or sheet, drink cold fluid, cold shower, cold or ice water bath, ice massage
Brian Danley, CFT
"Motivation is what gets you started. Habit is what keeps you going."