How Hot is Too Hot?
Training or competing in extremely hot weather can be dangerous and potentially fatal if the athlete suffers heat exhaustion or heat stroke. This is a combination of activity type, surface temperature, athlete hydration, training techniques and cooling strategies. Heat exhaustion occurs when the body loses excessive water and salt, typically through sweating, and can progress to heatstroke if not treated promptly. Heatstroke happens when the body’s temperature control system fails, leading to a dangerously high body temperature and potential organ damage. ( 1)
Heat Exhaustion:
Symptoms: Heavy sweating, dizziness, nausea, vomiting, rapid breathing and heartbeat, headache, muscle cramps, and extreme thirst.
Core Body Temperature: Elevated but generally below 104°F (40°C).
Treatment: Move to a cool place, loosen clothing, apply cool cloths, and drink plenty of fluids.
Heatstroke:
Symptoms: High body temperature (above 104°F or 40°C), confusion, altered mental status, loss of consciousness, seizures, hot and dry skin (or profuse sweating), and a rapid, strong pulse.
Core Body Temperature: 104°F (40°C) or higher.
Treatment: Call 911 immediately. This is a medical emergency that requires immediate attention to prevent serious complications or death. The athlete will likely require IV fluids, cooling , and medical attention and monitoring. ( 1)
Measuring Temperature of the Training Environment
There are times that athletic events need to be altered or cancelled due to extreme heat , but what is the temperature that this decision is made? First, the temperature must be measured on the training or competition surface, as various surfaces create different heat profiles, and other factors such as site specific humidity and wind play a factor. Traditionally , the media reports “dry bulb “ temperature, or the temperature and then relative humidity of the air. This is expressed as a “heat index” or “ feels like” temperature in what the air feels like to humans when they are outside. International sporting organizations such as the International Olympic Committee, use a measure called “ Wet Bulb “ Temperature. ( WBGT) Wet Bulb temperature is defined as “the lowest temperature to which air can be cooled by the evaporation of water under the current atmospheric conditions”. ( 2) It takes into account temperature, humidity, radiant heat from sunlight, and wind speed, 1 meter above the playing surface. Wet Bulb temperature focuses on the actual cooling capacity of the air. Wet Bulb Temperature is always lower than a heat index value in hot environments.
How Hot is too Hot to Train and Compete?
General extreme heat advice suggests that it is not safe to exercise with a wet bulb temperature of greater that 35° C, and humans have a challenge performing any work in that heat. However most sport organizations will use 32° C WBGT as the limit for safe sport participation . An example is that a “ dry” heat temperature of 40°C and 50% humidity equals 30.9°C WBGT.
Advice for sports participation depends on multiple factors. The type of sport such as soccer vs field events in athletics, or football ( with equipment ) vs archery. It involves the equipment/clothing required to participate in the sport, the ability for athletes to take breaks to cool off and re-hydrate, and ability to stand in shade out of direct sunlight. All of these factors will determine play time changes and breaks , as well as if the event can continue or needs to be rescheduled.
Many sports have their own extreme weather policy either provincially or nationally. This includes swimming water temperature for swim meets, triathlons, etc.
There are available apps that will estimate Wet bulb temperature. Sport PEI also has an advanced temperature gage that measures Wet Bulb temperature on the field of play. It can be borrowed for events that may have to monitor heat for participation and it is available in the Sport Performance Hub. Contact shouse@sportpei.pe.ca.
- Mayo Clinic 2025 Website https://www.mayoclinic.org/diseases-conditions/heat-exhaustion/symptoms-causes/syc-20373250#:~:text=Complications,that%20can%20result%20in%20death.
- CDC 2018 Evaluation of Occupational Exposure Limits for Heat Stress in Outdoor Workers — United States, 2011–2016.