Many people aren't conditioned to the physical stress of outdoor activities and are unaware of the potential dangers of being outdoors in cold weather. When winter sports enthusiasts fail to take certain precautions, accidental hypothermia can result. Hypothermia is a drop in body temperature to a subnormal level. It occurs when a person's body can't produce enough energy to keep the internal body temperature warm enough. It's a potentially fatal condition.
Heart failure is the cause of death in most cases of hypothermia.
Children, the elderly and those with heart disease are at special risk. As people get older, their ability to maintain a normal internal body temperature often decreases. Because elderly people seem to be relatively insensitive to moderately cold conditions, they can start to suffer the effects of hypothermia without knowing they're in danger. People with coronary heart disease often suffer attacks of chest pain called angina pectoris when they're outside in a snowstorm. Some studies suggest that harsh winter weather may increase a person's risk of heart attack due to overexertion.