Extreme heat during summer creates serious health risks for people who exercise or play sports outside. Experts at the UCLA Heat Lab say temperatures over 90°F (32°C), especially with high humidity, can push the body beyond safe limits. The National Oceanic and Atmospheric Administration warns that a heat index between 90 and 103°F requires extreme caution, while anything over 103°F is considered dangerous. This is because the body works to stay at a normal temperature of 98.6°F (37°C) by sweating. However, when the air is humid, sweat dries more slowly, which makes it harder for the body to cool down. This can lead to dehydration, heat exhaustion, or even heat stroke.

The Centers for Disease Control and Prevention explains that heat affects many parts of the body, including the heart, lungs, and muscles. Early signs of heat-related illness include muscle cramps, dizziness, and nausea. If not treated, these symptoms can lead to serious conditions like heat stroke or rhabdomyolysis, a rare condition that breaks down muscles quickly. Health experts recommend exercising during cooler times of day, staying in the shade, taking regular breaks, and drinking enough water. Experts also note that people often misjudge how hot they feel, which makes the risk higher. Awareness and preparation are important to stay safe in extreme heat.