Death in the heat: Can football heat stroke be prevented?

Exertional heat stroke has claimed the lives of nearly 100 high school and college athletes in the past 50 years, mostly in the first two to four days of football practice. Although it is a preventable cause of death, 21 relatively anonymous young athletes died between 1995 and 2001, after several years with no exertional heat stroke deaths in high school and college football. The recent deaths of two professional athletes have focused attention on exertional heat stroke and the prevention strategies that can save lives in the future.

To reduce morbidity and mortality, the same rapid response is required for a "heat attack" as for a heart attack. It is clearly evident from the road race and armed services exertional heat stroke experience that prompt recognition and aggressive on-site treatment saves lives and reduces morbidity. The adage from these experiences is "treat heat first and transfer later."

It is not the absolute degree of tissue temperature elevation that is important in survival, but rather the length of time that the body temperature is elevated above a critical level in the range of 106ºF. In mathematical terms, reducing the area under the heating-cooling curve above the 106ºF line in degree-minutes is critical to the outcome of heat stroke no matter what the initial or peak core temperature. Preventing heat stroke deaths in football will take a team effort on the part of all involved in the sport, including the administrators, coaches, and athletes to recognize and treat heat stroke victims without delay.

Reviewing the circumstances of several recent exertional heat stroke deaths suggests some simple interventions and performance markers that will improve the safety profile for football players. In all physical activity, especially in full football gear, the ambient conditions are critical for safety. It has always perplexed me that people are willing to say it is too cold to play but unwilling to concede to the heat. The occurrence of exertional heat stroke can be reduced with simple measures that accept the athlete’s work load limitations in the heat, and the risk of dying from heat stroke can be eliminated with early recognition and rapid treatment.

The football players who died of heat-related causes in the past few years share some common elements. First, and probably most important in the cascade of events, it was hot and humid at the time of the incident. Second, it was the second or third day of practice and the players were not acclimated to the heat and humidity. Third, they were large young men and boys with an increased heat capacitance. Fourth, they all vomited during the current or preceding practice and were allowed to continue participating in practice. Fifth, they were not performing in practice up to their usual or expected level of skill. And finally, the players were wearing more than shorts and T-shirts before they were acclimated to the heat.

Attention to the training and competition environment is, in my opinion, the most important factor in reducing the incidence of exertional heat stroke. Uncompensible heat stress conditions are common in the early football season. Although it is important that athletes are exposed to heat to acclimatize to the potential game conditions, it is not worth the risk of dying in known high-risk conditions, and heat exposure must be introduced in gradually increasing doses. The complicating and exacerbating factor in football is the uniform. The uniform, all or in part, has a high (insulation) R-value that traps heat by limiting evaporative and convective heat loss during and after activity. Athletes in full uniform exercised for 30 minutes and rested for 30 minutes do not return to baseline body temperature and will elevate the core temperature with each repeat bout of exercise. The effect is lessened, but not negated, by removing the football pants to expose more skin for heat loss.

Large players can accumulate and store more heat than their smaller counterparts. This is useful for continued activity in hot conditions until critical temperature thresholds are exceeded and the excess heat must be removed for survival. From the clinical perspective, this allows the athlete to participate too long in hot conditions and increases the risk of tissue damage from prolonged elevation of body tissue temperature.

The logical prevention strategies that must be instituted at all levels of football practice include a heat and humidity cascade linked to allowable work load, including intensity and duration. Within the work-rest parameters, fluid and salt replacement should be accomplished on a combined mandatory and ad libitum schedule to maintain optimal fluid status. The model practice schedule should accommodate acclimatization of the players with special precautions for those who have a history of heat collapse or are at increased risk due to large mass (body mass index > 30).

Players should have three to five days of conditioning and drills in shorts and T-shirts that could include the helmet after one or two days, and three to five days of helmets and shoulder pads before allowing the full uniform in practice. Pads and helmets should be removed to promote body heat loss when not needed for protection. The amount of uniform should also be tailored to the heat and humidity utilizing a graph, especially in the early season during double sessions while the athletes are adjusting to the heat.

When reduction strategies fail, early recognition is the key to player survival. A heated brain does not function well, so depending upon the judgment of the athlete with an elevated core temperature is not adequate for heat safety. However, an athlete who complains of not feeling well or not "being right" should be given the latitude to cool or be checked to ensure that the rectal temperature is not elevated above 103ºF. The onset of heat stroke in football players seems sudden and rapid, but reviewing death cases in football heat stroke victims shows some common, although sometimes subtle, indicators of impending catastrophe. Coaches and teammates must be vigilant and feel free to report athletes who are vomiting or who have changes in routine performance.

I have often made the statement that football is a "brain stem" sport. Not to denigrate the sport, as it requires focus and cognitive function to perform well, but to emphasize that many of the routine activities of practice have been repeated so many times by players that they can perform reasonably well even when the brain is not fully engaged or when it is overheated. A player who staggers and stumbles, misses assignments in blocking drills, or does not perform to expectation in the heat may not be "goofing off" or "not trying," but instead may be in trouble with the heat. Coaches and athletic trainers need to look closely at players who are performing below par and evaluate their heat status. In hot conditions, we should institute the buddy system to have players watch out for each other, as with swimming to prevent drowning or with Nordic skiing in the cold to prevent frostbite. This will take some of the pressure off the coaches and allow players to help each other.

Vomiting is not normal during exercise, especially in the heat. Vomiting occurs because the gastrointestinal tract is no longer working properly and the ingested fluids are not absorbed. Two things happen in the vomiting athlete. First and most obvious, sweat losses are not replaced, so the athlete becomes dehydrated and at greater risk for heat stroke, as both sweating and vascular heat transport are decreased. Second, the loss of electrolyte through emesis will further complicate the clinical picture and treatment of heat stroke. An athlete who vomits in football practice, especially during the first few days of double sessions, should be assumed to have heat injury and is at great risk for heat stroke. These athletes should never be returned to practice on the same day and should be evaluated by an athletic trainer or physician familiar with football and heat illness prior to return practice on the following day.

On-site cooling in a tub of ice water to bring the temperature down rapidly is life-saving and practice sites should be equipped with tubs to immerse players who show signs of heat injury or heat stroke. In my field experience, treating runners with exertional heat stroke in ice water tubs, the rectal temperatures can be reduced from above 108ºF to below 102ºF in 20 to 40 minutes. Heat stroke and heat injury can be identified with a rectal temperature measurement, and if a rectal temperature cannot be obtained it may be best to cool the athlete while waiting for the emergency medical transport team to arrive. When athletes falter in hot conditions, one should consider it a heat attack and cool the athlete immediately in a tub of cold water.

The incidence of exertional heat stroke in football practice is reducible with attention to environment, acclimatization, equipment, and hydration; and heat stroke death in football practice is preventable with early recognition and on-site core temperature reduction. Recognizing heat stroke before the final collapse requires a change in football attitude and close observation of player performance and well being.

A prominent coach in the 1950s stated to a player’s father that the practice conditions with no water in the heat were necessary because, "it is war out there on the field," to which the father of the heat stroke victim replied, "I’ve seen war; football is a sport." It is time to accept that, as with adding water to the practice sites, it is time to utilize the temperature-humidity scales and acclimatization to protect the players.

Reprinted with permission from Current Sports Medicine Reports, Vol. 3, No. 1, February 2004.