Heat Illness: Dangers of Athletic Practices in the Summer

Pre-season sport practices will be kicking off over the next few weeks. With the excitement of another season fueling summer practices, comes the dangers of playing in hot and humid conditions. There are three forms of exertional heat illness which players, parents, and coaches should be familiar with. These are heat cramps, heat exhaustion, and heatstroke. For more about what exertional heat illness is and is not, read here.

Three Forms of Exertional Heat Illness

Heat cramps are the least serious and typically involve painful cramping of large muscles (commonly the calf muscles). Heat cramps are caused by sodium loss and dehydration which accompany high rates of sweating. Treatment of heat cramps involves moving the athlete to a cooler environment and administering fluids such as sodium containing sports drinks. Prevention strategies include remaining hydrated during practices and liberal use of sodium containing foods or beverages.

Heat exhaustion is a more serious disorder characterized by fatigue, dizziness, nausea, vomiting, fainting, and a weak, rapid pulse. In such cases, the body’s cardiovascular system is unable to meet the needs of the body as it becomes dehydrated. The underlying cause is dehydration caused by fluid loss from sweating. Athletes who are unfit or not acclimated to the heat are more susceptible. Treatment involves resting in a cool environment with the feet elevated to facilitate blood return to the heart. Administration of fluids (water or a sodium containing beverage) is also recommended.

Heatstroke is a life-threatening disorder requiring immediate medical attention. It is caused by an inability to control core body temperature. A core body temperature exceeding 104 degrees, confusion, disorientation, and unconsciousness are hallmark signs. If left untreated, body temperature will continue to rise progressing to coma and even death. Rapid cooling of the body in an ice bath is the best form of treatment. If cold-water immersion is unavailable the athlete should be wrapped in cold wet sheets while others fan the body.

Impact of Humidity

High humidity means the air contains many water molecules. In these instances, the air cannot accept much more water. During exercise in the heat, excessive body heat is lost through evaporation of sweat at the surface of the skin. If humidity is high, sweating will be much less effective in releasing body heat because evaporation is inhibited. Even though sweat secretion will continue during the exercise bout, without evaporation the rate of core body temperature may continue to rise. Therefore, high humidity increases the likelihood of experiencing any of the three forms of exertional heat illness.

Preventative Steps

Athletes can take preventative steps to minimize the detrimental effects of playing in hot environments. Strategies which promote heat adaptation have been shown to assist with an athlete’s ability to tolerate and perform in hot and humid environments. Adaptation requires a series of gradual progressively increasing temperatures in order to produce sufficient adaptations. Longer and more frequent heat exposures produce heat adaptation benefits resulting in the greatest capacity and performance benefits. Regimens lasting more than 14 days show the greatest benefits.

Coaches and parents should take preventative steps when threatening conditions are present. Practices in the early morning or evening can avoid the severe heat stress of midday. Fluids should be available and athletes should be given drink breaks every 15 to 30 minutes. Weighing athletes before and after exercise can help estimate individual sweat rate and fluid needs. Fluids containing electrolytes and carbohydrate can provide benefits over water alone. Light colored, lightweight, loose-fitting clothing should be worn whenever possible. And finally, heavy use of equipment (i.e., football pads and helmets) should be minimized or avoided early in the practice season when athletes are not yet fit or acclimated to the heat.


  1. Bergeron, M. F., Bahr, R., Bärtsch, P., Bourdon, L., Calbet, J. A. L., Carlsen, K. H., … Millet, G. (2012). International Olympic Committee consensus statement on thermoregulatory and altitude challenges for high-level athletes. British Journal of Sports Medicine, 46, 770–779. https://doi.org/10.1136/bjsports-2012-091296
  2. Kenney, W. L., Wilmore, J., & Costill, D. (2015). Physiology of sport and exercise (6th ed.). Champaign, IL: Human Kinetics.
  3. Tyler, C. J., Reeve, T., Hodges, G. J., & Cheung, S. S., (2016). The effects of heat adaptation on physiology, perception and exercise performance in the heat: A meta-analysis. Sports Medicine, 46(11), 1699–1724. https://doi.org/10.1007/s40279-016-0538-5

Subscribe to Our Newsletter and Receive Similar Articles

Want to move better without pain? Join thousands of others who subscribe to our newsletter and get exclusive access to more helpful tips and exercises. Here's an example issue of our newsletter, so you can get a preview of what you are signing up for.

* indicates required