Effects of Exercise in Cold Weather
Little is known about adaptation/acclimatisation to exercise in cold. When faced with excessive heat loss the body responds to maintain body temperature by vasoconstriction and enhanced metabolic heat production. Problems associated with exercise in cold are hypothermia, local cold injury (eg frostbite, chilblains/erythema pernio), dehydration (due to dulling of thirst response from cold), respiratory problems (eg bronchospasm), increased fatigue (due to subjective loss of sensation) and increased risk of mechanical injury,
Wind and moisture are just as important as temperature when assessing the severity of an environment for exerciser. Heat loss is greater if wet or if wind blowing. Charts are available to show the ‘wind chill’ to take account for these and guidelines are available about the continuance of events if the wind chill factors is below a certain level.
Precautions for exercise in cold environment:
• use insulative clothing to trap air close to body prevents heat loss
• use multiple layers of clothing progressively remove as warm up progresses
• more stretching if explosive muscle actions are needed
• using additional layers of clothing during breaks in activity
• adequate hydration
• use of cold stress index delay/cancel event if below a certain level
Defined as a core temperature below 35°C (becomes serious when gets down to 32.2°C). Develop fatigue, shivering, loose control of movements (ataxia), disorientated, tachycardia, poor judgment and reasoning later, shivering stops, marked ataxia, significant impairment of mental state, cardiac arrhythmias, later loss of consciousness/coma.
Remove wet clothing; keep out of wind; add heat to body gradually – use blankets, sleeping bags and warm drinks warming must happen in a controlled way and not rapidly.
If severe cardiac monitoring and monitoring of oxygen content, IV access, rectal thermometer, may need CPR and intubation rewarming by venous haemodialysis. Cardiac arrythmias may occur during rewarming.
Muscles are stiffer in cold environments (especially if larger and rapid movements are needed) and nerve conduction is slower ( decreased co-ordination) increased risk for muscle and tendon strains and tears.
Prevention – adequate clothing and warm-up (stretching and aerobic activity).