Playing under a clear blue sky is absolutely critical and pivotal in sports. However, it's important that you play in a safe surrounding. Among these is the temparature. If it's cold, players tend to wear long sleeve shirts and possibly even gloves.
Playing when the sun is out is a different story. This is because there's no telling what it will be. It could be warm with a cold breeze or, at worst, a blazing heatwave. It's in the cases of the latter that breaks are taken. Even when these are granted, that doesn't mean that everyone involved will be safe. Playing in those conditions can take it's toll on people and can lead to serious conditions.
Prolonged exposure to heat causes significant stress on the human body, which may lead to heat exhaustion and/or the exacerbation of pre-existing health conditions. This is particularly concerning for those who spend time outdoors, such as those who participate, spectate, officiate and volunteer at outdoor sporting events (Mason, King, Peden, Leicht, Franklin, 2024).
Increased exposure to extreme heat increases the risk of heat-related illness, which can range from minor symptoms such as cramps and fatigue to potentially fatal conditions such as heat stroke. Heat-related illnesses are preventable with appropriate action plans. Therefore, it's crucial to implement measures to mitigate the risks posed by extreme heat during sporting events to ensure the safety and well-being of those participating, officiating, working and attending (Mason, King, Peden, Leicht, Franklin, 2024).
Exercising in hot conditions increases body core temperature and excessive humidity prevents the body's ability to regulate this heat load through sweating. Athletes who are at greatest risk of heat-related illness include those who aren't properly acclimatised to the environmental conditions; have pre-existing health conditions; play high intensity sport and wear protective equipment that prevents evaporative heat loss (Mason, King, Peden, Leicht, Franklin, 2024).
During these extreme environmental conditions, officials, spectators, workers and volunteers may also be in danger as they are required to stand or move in these hot conditions for extended periods of time. During outdoor sporting events, where shade, cooling and ventilation are limited, there is an increased risk of heat-related health events, especially for those unacclimatised to the climate in which an event is being held. Approaches to alleviate the impact of heat on health and performance are crucial to ensure that all who attend are unharmed during these popular sporting events (Mason, King, Peden, Leicht, Franklin, 2024).
As temperatures rise across the globe, it's paramount that organisers and governing bodies of mass-gathering sporting events consider the impact of extreme heat on all individuals who attend, including: athletes; officials; spectators; volunteers and workers. The burden of heat on mass-gathering events is wide ranging (Mason et al., 2024).
Ultimately, there must be awareness of the impact of extreme heat on health at mass-gathering sporting events at the individual (e.g. pre-cooling, drinking breaks), organisational (e.g. time and place of competitions, adjustment of rules and regulations) and infrastructure levels (e.g. instillation of water dispensers, green roofs and facades) (Mason et al., 2024).
Overmotivated athletes can overheat by doing too much too fast or trying to endure too long. An Australian runner, out of shape, sped to the front of a hot race and kept going hard until he dropped from heat stroke at 4.5 miles (Eichner, 2006, cited, Lee et al., 1990). The same happened to a novice runner who, on a mild day, sped up at the end of a six-mile race (Eichner, 2006, cited, Hanson et al., 1979). Both runners were lucky to live; speed and metabolic rate influence rectal temperature in distance racing (Eichner, 2006, cited, Noakes et al., 1991).
Agonising tableaus of endurance were seen at the 1984 Los Angeles Olympic Games and the 1995 Hawaii Ironman Triathlon. In Los Angeles, marathoner, Gabriela Andersen-Scheiss, not trained for heat, entered the stadium dazed and wobbling. In a final lap that seemed to last forever, she waved off help and collapsed at the finish. In Hawaii, seven-time winner, Paula Newby-Fraser, losing her lead, skipped aid stations late in the run and collapsed near the end. After rest, cooling and hydration, she was able to walk to the finish (Eichner, 2006, cited, Eichner, 1998).
Similar lessons come from the military. A soldier died of heat stroke marching at night, carrying extra weight. He completed just 2.5 miles (Eichner, 2006, cited, Assia et al., 1985). Running generates about twice the heat of marching. Of 82 heat-stroke cases in Israeli soldiers, 40% were from brief exercise, as in the first three miles of a run. Overmotivation was a risk factor (Eichner, 2006, cited, Epstein et al., 1999
In summer sports, it’s not the heat but the heat and humidity. In football, body temperature rises - in a sawtooth line - ever higher the longer practice goes on. So, during a hard practice in full gear, heat stroke is possible at any combination of ambient temperature above 80 °F (26.7°C) and relative humidity above 40% (Eichner, 2006, cited, Kulka & Kenney, 2002).
Athletes in the heat can sweat 1-2L an hour and most athletes drink less than they sweat. The result is dehydration. Dehydrating only counts to 2% of body weight - just five pounds in a 250-pound linebacker — can impair physical performance (Eichner, 2006, cited, Walsh et al., 1994). Dehydration increases heart rate and decreases cardiac output. Perceived exertion of the work increases as dehydration drains mental sharpness and willpower along with muscle power and endurance. Dehydrated players also heat up faster (Eichner, 2006, cited, Latzka & Montain, 1999).
Early warning signs of impending heat stroke may include: irritability; confusion; apathy; belligerence; emotional instability or irrational behaviour. The coach may be the first to note that a player, heating up, can no longer think clearly. Giddiness, undue fatigue and vomiting can also be early signs (Eichner, 2006).
Paradoxical chills and goose bumps signal shutdown of skin circulation, portending a faster rise in temperature. The player may hyperventilate - just as a dog pants — to shed heat; this can cause tingling fingers as a prelude to a collapse. Incoordination and staggering - "running like a puppet on a string"- are late signs, followed by collapse with seizure and/or coma. Upon collapse, as in all three football players who died in 2001, core body temperatures can be 108 °F (42.2 °C) or higher (Eichner, 2006).
The cooler athletes stay, the better they play. In team sports, take frequent cooling breaks. Provide shade, ice water and misting fans for rest breaks. As the temperature rises, reduce practice pace and duration and increase rest breaks. Have players sit in cold tubs after practice. Hold practices earlier and later, with more time between - time for rest, recovery and cooling (Eichner, 2006).
In hot road races, tips include: stay hydrated; run comfortably; avoid long sprints; "read" your body; and seek help early for illness. Confusion can limit self-diagnosis, so race monitors can help. Runners in trouble can become belligerent, refusing to stop until they collapse. Naïve crowds may urge on suffering athletes, chanting, "Keep going, you can make it." Monitors can recognise early warning: incoherence; irrational or bizarre behaviour or poor competitive posture (Eichner, 2006, cited, Eichner, 1998).
Hydration helps prevent heat stroke but there is no advantage to consuming fluid in excess of sweat loss. Likewise, it’s not necessary to overhydrate the night before or during the hours prior to a long run or practice. Teach athletes to drink for their needs. During training, have them weigh in before and after a workout and learn to adjust fluid intake to minimise weight loss (Eichner, 2006).
If weight loss does occur, rehydration after activity is critical; drink 20-24 ounces of fluid for every pound of weight loss. Also, eat foods with a high water content (fruits & vegetables). A sports drink beats plain water because it has sugars to fuel muscles and brain, flavouring to encourage drinking and sodium to hold fluid in the body and help replace sweat losses (Eichner, 2006).
Extreme heat makes it especially hard for your body to cool down, so you need to be extra careful if you exercise or play sports when it's baking outside. Your brain tries to keep your body within a degree or two of 98.6 °F and it does so in part by triggering sweat. When sweat dries, it carries away heat from your body's surface (Associated Press, 2025).
When sweat can't do its job — because your body is generating a lot of heat or it's too hot and humid to cool down — you are at risk of becoming dehydrated or even getting a heat-related illness such as heat exhaustion or heat stroke (Associated Press, 2025).
Bharat Venkat, an associate professor at UCLA and the director of the UCLA Heat Lab, says heat can impact the entire body. "We’ll often talk about heat cramps. We’ll talk about heat exhaustion. We will talk about heat stroke," he said. "But it’s actually much wider than that. Heat can really impact every system in our body, our hearts, our lungs" (Associated Press, 2025).
The higher the temperature, the harder it is for the body to stay cool but humidity plays a big role too. High humidity makes it feel hotter than the temperature because it makes sweating less effective. There's so much water in the air already that it can't take up much more - including the water in your sweat (Associated Press, 2025).
The heat index, which factors in humidity and is included on many weather forecasts, provides a sense of how hot it really feels and what's dangerous for prolonged exposure or strenuous activity (Associated Press, 2025).
The National Oceanic and Atmospheric Administration (NOAA) says people should start exercising "caution" when the heat index reaches 80 to 90 degrees and "extreme caution" from 90 to 103 degrees. It labels everything over 103 "danger" or "extreme danger." NOAA has a chart that shows how the heat index is affected by humidity. For example, a day that is 90 °F (32 °C) can hit the "danger" level with 70% humidity (Associated Press, 2025).
If you want to exercise in the heat, here are some tips to say safe, according to the U.S. Centers for Disease Control and Prevention:
- Time your exercise and outdoor activities for the coolest parts of the day.
- Try to exercise in the shade as much as possible.
- Take frequent breaks.
- Drink lots of fluids and limit drinks that are high in sugar, caffeine and alcohol. Don't wait until your are thirsty to drink more.
- Exercise with someone so you can check on each other or pair up with a team-mate (Associated Press, 2025).
If you start to feel any of these symptoms, stop exercising, get to a cool place and seek medical care:
- Muscle cramping or muscle weakness
- Shortness of breath
- Dizziness
- Headaches
- Nausea (Associated Press, 2025).
"Athletes and other folks who regularly engage in strenuous activity often think that they can handle it," UCLA’s Venkat said. "But a lot of studies have shown that we’re really bad at gauging how hot it is" (Associated Press, 2025).
A common heat-related illness is heat exhaustion, which can be marked by rapid heartbeat, fast breathing, headache, nausea and muscle weakness or cramping. It can develop into the more serious heat stroke, when your body can no longer control its temperature. Symptoms include confusion or slurred speech, seizures or even loss of consciousness (Associated Press, 2025).
Heat also increases your risk for a rare condition called rhabdomyolysis, which causes the rapid breakdown of muscles. If you think you or a fellow athlete are in danger, call for help, give them fluids — preferably water — and try to cool their bodies with cold water or cold compresses (Associated Press, 2025).
Even if you think you can deal with the heat, Venkat said, "It’s better to kind of take a step back and take it easy" (Associated Press, 2025).
Playing in the heat can certainly be dangerous. It should never be taken for granted. Athletes should always adhere to the safety measures. It's vital that athletes stay fit and healthy. A panic will happen should one pass out as a result of a heat related illness.
Reference List
Eichner, E.R. (2006). 'Heat Stroke In Sports: Causes, Prevention and Treatment,' Sports Science Exchange, 15 (3).
Franklin, R.C., King, J.C., Leicht, A.S., Mason, H.M., Peden, A.E.. (2024). 'The impact of extreme heat on mass-gathering sporting events: Implications for Australia and other countries,' Journal of Science and Medicine in Sport, 27 (8), pp. 515-524. doi: 10.1016/j.jsams.2024.04.015.
The Associate Press. (2025). Exercising or playing sports in extreme heat can be extremely dangerous. Available from: https://www.nbclosangeles.com/news/national-international/exercising-or-playing-sports-in-extreme-heat-can-be-extremely-dangerous/3731727/ (Accessed: 1 July 2025).