Heat illness: A general term for problems caused by activity in high temperatures.
Heat Emergencies: Heat cramps, heat exhaustion and heatstroke are all degrees of heat emergency. Action should be taken to cool the person and be prepared to call for medical attention if shock, seizures or fainting occur.
Signs and First Aid for Heat Emergencies
Heat cramps: Painful spasmodic contraction of muscles, usually abdominal or legs, caused by work in extreme heat.
Heat syncope: Fainting or sudden loss of strength due to excessive heat gain. Medical attention (calling 911) is encouraged if the person faints.
Heat exhaustion: Signs include heavy perspiration, weakness, fainting, vomiting, and cold, pale and clammy skin. It is possible that the person has a normal temperature. They may experience collapse, with or without loss of consciousness. This may be suffered in high heat/humidity, largely resulting from the loss of fluids and electrolyte imbalances (i.e. loss of sodium).
Heat stroke: The skin is hot, dry, and red (hyperpyrexia). Often heat stroke is proceeded by heat exhaustion and its symptoms. Other signs include rapid heartbeat, confusion, loss of consciousness. This the final stage in heat exhaustion, when the body is unable to lose heat, body temp above 106F occurs, and death may ensue.
Consider the small range of body temperatures above normal within which we humans may survive: about 8 degrees!
Sunburn: Redness and pain. In severe cases swelling of skin, blisters, fever and headaches.
Remember that the higher one's intensity of activity, the greater the energy produced, the faster one runs the more internal heat that is produced. Think of the ambient temperature conditions will feel about 20F hotter while you're training or racing. Where is that internal heat going to go if the conditions outside your body are as hot as your body or higher? Don't cook yourself to illness or worse.
Athletic training is not intentional suffering. Let's "train, don't strain."
Sources: Coach Gary Westlund, ACSM H/FI, Marathon Coach for The Arthritis Foundation/MN - Joints in Motion Teams and American Diabetes Association/MN, TEAM DIABETES
Auerbach PS. Wilderness Medicine. 4th ed. St. Louis, Mo: Mosby; 2001:240-316.
DeLee JC, Drez Jr. D, Miller MD, eds. DeLee and Drezs Orthopaedic Sports Medicine. 2nd ed. Philadelphia, Pa: Saunders; 2003:763.