Heat injuries, heat disorders, heat-related illness: all refer to a medical condition arising from failure of the body to properly regulate its heat level, resulting in over-heating. Heat injuries are common in physical activities of a strenuous nature (sports, outdoor activities, endurance events, outdoor recreation sports, outdoor power sports, outdoor water sports). These activities do not need to take place in an outdoor setting for someone to be at risk of developing a heat injury. It is important to realize that heat injuries can have very serious consequences including damage and failure of major organs in the body leading to death.
Certain factors can increase the risk of heat injuries.
- Weather conditions. Hot, humid and sunny environments are associated with higher incidence of heat injuries. The temperature of a person’s skin is lower than that of his body core, usually 86-90 degrees Fahrenheit. Thus when the air temperaure is higher than this, heat is gained by the body through radiation. If the air humidity is high, this reduces sweat evaporation and leads to decrease in heat loss through sweating. It should be appreciated that heat injuries can occur at night if the conditions of heat and humidity are high. In sunny weather, there is heat gain from the solar radiation. There is less heat gain and improved heat loss when the weather is cloudy, cool and breezy.
- Prolonged high intensity physical exercise or activity. Such activity increases the body’s heat gain as a result of repeated muscle contractions, while the duration of the activity may prolong a person’s exposure to unfavorable environmental conditions and a greater risk of heat injuries.Insufficient hydration status, illness and insufficient cardiovascular and sweating response are other factors that increase risk.
- Heat injuries represent a continuum of a medical condition rather than the usual per¬ception of distinct injuries: heat cramps, heat exhaustion, and heat stroke.
- The current opinion on muscle cramps is that these arise from muscle fatigue and not necessarily from over-loss of electrolytes. However, exercise in hot conditions with excess loss of sweat may be related to muscle cramps, which are then sometimes known as heat cramps.
Heat stroke exhaustion is conventionally considered as due to the inability of the cardiovascular system to meet the needs of both the contracting muscles and the supply of blood to the skin for sweating processes. The common signs symptoms of heat stroke include thirst, fatigue, weakness, and headaches. Heat stroke is generally considered when the body core temperature exceeds 104 degrees Fahrenheit, and represents a failure of the body’s temperature regulation mechanisms. The person will have experienced the signs of heat exhaustion and may then show signs of decreased sweating, feeling faint or dizzy, mental irritation (confusion, altered consciousness, irrational behavior), and finally collapse. In addition, there may be feelings of thirst, by which time the body has already started to dehydrate. Salt staining of clothing indicates a loss of minerals associated with excessive sweating.
Once a person shows signs of heat injury, treatment should begin immediately. This includes:
- Reducing the intensity of physical exertions, stopping if necessary
- Movement to a cooler location (eg. more shade, breezy, under a fan, in an air-conditioned room)
- Consumption of water or electrolyte-containing fluids, preferably cooled to lower body core temperature and to improve absorption
- Removal of clothing to assist with cooling, wherever practical
- Application of cooling methods (towels soaked in cold water, ice packs, immersion in cold water, etc)
