Prolonged heat stress during exercise can lead to heat illness, serious health complications and even fatalities in athletes of all ages.

  • Heat-related illnesses are a real concern for all athletes, but parents and coaches need to be extra conscious of young athletes who may not know when they need to take a break.
  • Exertional heat stroke is one of the top three causes of sudden death in athletes.
  • Exertional heat-related illnesses must be treated immediately with rapid body cooling.
  • Heat-related illness isn’t confined to hot days – individuals are also susceptible on days with moderate temperatures and high humidity.

Exertional Heat Illness and Exertional Heat Stroke

Exertional heat illness, or exertional heat-related illness, can affect athletes during high-intensity or long-duration exercise and result in collapse, muscle cramping, heat exhaustion, or exertional heatstroke – which can become life-threatening if not treated.  Source Exertional Heat Illness during Training and Competition

Exertional heat stroke (EHS) is the most severe form of exertional heat illness, and is characterized by a body core temperature of >40° C and symptoms or signs of organ system failure – most frequently central nervous system dysfunction.

The clinical changes associated with EHS can be subtle and easy to miss if coaches, medical personnel, and athletes do not maintain a high level of awareness and monitor at-risk athletes closely.  Source Heat-related illness in sports and exercise


What happens when you get heat stroke?

Have you ever suffered from exertional heat stroke? This condition is caused by intense activity in the heat and is one of the top three killers of athletes and soldiers in training. Douglas J. Casa explains heat stroke's tremendous effects on the human body and details an action plan in case it ever happens to someone you know.

Who's At Risk?

While certain people are more prone to collapse from exhaustion in the heat (i.e., those who are not heat acclimatized, using certain medications, dehydrated, or recently ill), exertional heat stroke (EHS) can affect seemingly healthy athletes even when the environment is relatively cool.  Source Exertional Heat Illness during Training and Competition

Heat-related illnesses are a real concern for all athletes, but parents need to be extra conscious of young athletes who may not know when they need to take a break. Parents and coaches need to pay even more attention to those who play sports that require wearing heavy protective equipment, like American football. Studies have shown that the risk of developing a heat-related illness is 11.4 times higher in American football than all other sports combined. Source Heat-Related Illness and Young Athletes: 3 Important Things Parents and Coaches Need to Know

The number of injuries associated with exertional heat illness in the United States – most of which involved young people playing sports – increased by more than 130 percent between 1997 and 2006.  Source Exertional Heat-Related Injuries Treated in Emergency Departments in the U.S., 1997–2006

Management and Adaptation Solutions

Rest Breaks

Ensure athletes are able to take regular cooling breaks in shaded areas or cool spaces to prevent overheating.

Aerobic Conditioning

People who are in better shape have a lower pre-exercise core temperature and sweat earlier when exercising, enhancing heat loss from the body during exercise compared to less fit individuals.

Heat Acclimatization

Heat acclimatization is a process of repeatedly (7-14 days) exposing oneself to hot conditions to gain physiological and perceptual benefits. This process of slowly getting used to the heat is a recommended prevention method.

During the first 10 to 14 days of heat exposure, athletes should gradually increase the duration and intensity of their exercise or activity. This is especially important for children and teens who may be out of shape and/or considered overweight (BMI over 25). The National Athletic Trainers’ Association suggests a 14-day period in its high school-specific guidelines for preseason heat acclimatization.

It’s also important to understand that heat-related illness isn’t confined to hot days. Individuals are also susceptible on days with moderate temperatures and high humidity (source).

Pre-Exercise Cooling / General Cooling

The main intention of pre-exercise cooling and cooling in general – such as submerging the body in cold water, or being in a cold room, drinking cold fluids including ice slushies and wearing cooling vests – is to lower the body’s temperature before exercise to extend the body’s heat storage capacity to delay the onset of fatigue and reduce the risk of heat related illness.

The effectiveness of these strategies in altering core temperature may be limited as their benefits may not be able to be sustained throughout the duration of exercise. To counteract this limitation, considerations can be made to consider cooling during breaks and during exercise itself (if possible).  Source Efficacy of Heat Mitigation Strategies on Core Temperature and Endurance Exercise: A Meta-Analysis


Staying hydrated is one of the easiest ways to help prevent heat-related illness. Coaches and parents need to make sure unlimited amounts of water are available for athletes during practices and games, but it is also important for them to stress that athletes need to drink water before and after activity as well.


Early Recognition and Cooling in Case of Heat Illness

Early recognition of a heat-related illness is paramount to survival because the signs and symptoms are generally nonspecific:

  • Disorientation
  • Dizziness, weakness
  • Unusual behaviour
  • Headache
  • Vomiting

Heat stroke is a medical emergency – call for help immediately, and then cool the person down before moving them. Casualties should be immersed in cold water while waiting for emergency services to arrive. Tool tip Learn more about heat in the body.

Learn more

For information on personal cooling and heat illness detection and management, please see our section on managing and adapting to heat in the body.

Page Contributors

Jason Lee, Nicola Gerrett