PT on the Net Research

Dangers of Heat and Over Training


Due to the recent heat / training related death in the NFL, we thought it appropriate to consult NASM Director of Athletic Reconditioning, Alan Russell (a Certified Athletic Trainer and Performance Enhancement Specialist) on the dangers, symptoms and treatment of heat-related illness.

Heat illness can begin as simple muscle cramps and progress to heat exhaustion, then finally to heat stroke. Heat Exhaustion is usually characterized by excessive thirst, excessive sweating, moist & clammy skin, dry mouth, fatigue, weakness, mental confusion, and increased body core temperature. Placing the athlete in a cool environment, pushing fluids, and adequate rest will usually provide effective recovery for the athlete. Heat Stroke is characterized by abrupt headaches, absence of sweating, hot & dry skin, increased pulse rate, vomiting, and excessive core body temperature. The integrity of the skin can be confusing. A 1990 study by Shapiro showed that when the illness has progressed to heat stroke, the athlete continues to "sweat" although there is not much of a fluid component due to the excessive fluid loss as the illness progressed. Heat Stroke is a severe thermoregulatory condition and is extremely life-threatening. When Korey Stringer arrived at the emergency room, his core temperature was 108 F degrees. Mortality rates are 80% when the core temperature has risen that high.

Excessive heat and humidity can expedite this condition. When the body moves it creates heat. For the body to effectively cool itself, this heat must be dissipated. Approximately 95% of the heat is lost through the evaporation of body sweat. In high humidity conditions, the air already has a higher concentration of water, so evaporation is limited and slowed. However, the athletes sweat production is not decreased. So you have a situation where the athlete is producing heat faster than it can cool itself (altered thermoregulation). Sweat also has a high concentration of sodium, thus the "salty" taste. With profuse, prolonged sweating a negative balance of sodium & potassium is noted in the body. Without sodium & potassium replacement body functions begin to be impaired. Remember that muscles physiologically require the presence of sodium & potassium for contractions. This is very significant when the strongest muscle in the body is cardiac muscle, which also relies on optimum electrolyte balances.

It is unfair for the media to use this incident to describe an epidemic of heat-related illnesses in organized football. Although it is completely unacceptable that this unfortunate death happened at the NFL level with the quality of medical coverage, we must realize that exercising in the extremes of heat and humidity are normal occurrences. Athletes get cramps, rest a little, drink a little, then get right back into the action. This is a good opportunity for all of us to learn about heat illnesses, how they can affect the body, how to manage emergencies, and most importantly...how to prevent heat illness.