Although the warmer months are popular for training, scorching summer temperatures can quickly mean serious trouble for athletes.
Runners can encounter all kinds of health threats, including dehydration, heatstroke and, in extreme cases, death.
“It’s incredibly important to be aware of the temperature when exercising outdoors,” said personal trainer and former Olympic athlete Samantha Clayton, who is also Herbalife Nutrition’s director of worldwide fitness and education.
“The thermic stress that you put on your body when training in excessive heat is not great for [it],” she said.
“There’s a reason why a big bulk of marathons are early in the spring and fall,” said Runner's World Chief Running Officer Bart Yasso, who has run in extreme July temperatures of Iraq, Kuwait and California's Death Valley.
However, sweltering conditions don't always stick to the summer months. Marathons and races held during spring and fall have been called off because of unusually warm weather.
One person died and hundreds of runners fell ill as temperatures surged to the upper 80s Fahrenheit at the 2007 Chicago Marathon, prompting officials to cancel the race for the first time in 30 years.
Running in warm weather is perfectly doable, said Yasso, provided that runners look after themselves and adjust their paces accordingly.
Below are five expert tips for enduring and conquering the brutal summer heat.
Recognize the signs of illness
According the Centers for Disease Control and Prevention (CDC), extreme heat kills more than 600 people annually in the United States.
If a runner's body is signaling a problem, experts advise paying close attention.
It’s imperative to recognize symptoms of potentially deadly heatstroke, which happens when the body can't regulate its own temperature, according to the Boston Athletic Association (BAA).
Symptoms include vomiting; nausea; changes in mental state, including delirium and confusion; and rapid breathing and heart rate.
Experts recommend to stop running and possibly seek medical help if you feel dizzy or your skin feels strangely hot or cold.
The BAA stated that those with a history of heatstroke have a higher chance of experiencing heat illness in the future.
Let your body adjust to heat
Experts recommend that athletes give their bodies ample time to acclimate to performing in higher temperatures.
The gradual process takes between 10 and 14 days in higher temperatures, according to Dr. Chad Asplund, vice president of the American Medical Society for Sports Medicine (AMSSM).
Hydrate, but don’t overdo it
As little as 2 to 4 percent of water loss will significantly hinder an athlete’s performance, Asplund said.
Exercising elevates the body’s core temperature, putting runners at risk for heat exhaustion or life-threatening heatstroke, said Asplund, who has treated soldiers and athletes inflicted with sometimes fatal heat-related illnesses.
Experts advised runners, especially those prone to cramps, to consider electrolytes when rehydrating. The salt and sugar help carry fluids to cells faster than water by itself.
Yasso recommended carrying your fluid replacement of choice, be it a sports drink or water, if running between 30 and 45 minutes in warm weather.
Urine should appear light yellow when rehydrating after runs and maintaining a normal hydration status, Asplund said.
If feeling parched, experts suggested seeking shade in a cool place.
Although it’s rare, over-hydration can occur. Runners who drink an excess of fluid are at risk of potentially fatal hyponatremia, or water intoxication, Asplund said.
Heed the dangers of humidity
Humidity will make any warm-weather run feel more oppressive than normal.
High humidity impedes the rate of sweat evaporation from the skin, making it harder for the body to cool.
It also rapidly raises the body’s core temperature, Asplund said.
Because of this, the elevated temperature can literally cook an athlete’s insides, according to the BAA.
“If the weather is hotter or more humid than usual, the best thing to do is slow your pace – and your expectations – if you are racing,” Asplund said.
He also recommended getting familiar with the temperature, humidity and heat index of where you’re running that day.
Protect yourself from the sun
Experts agree that running in the early morning or during sunset are ideal times for avoiding extreme temperatures.
Clayton recommended training indoors whenever possible, and if it isn’t, try sticking to shaded areas.
The BAA advised that runners wear sunscreen containing at least 15 SPF and choose sunglasses that protect against harsh UVA and UVB rays.
If the weather is too hot, a hard workout may need to be rescheduled or modified, said Asplund.
“Heat exposure is cumulative, so in the very hot months, plan to have at least 8-10 hours of heat respite per day to offload some of the heat,” he said.
For more safety and preparedness tips, visit AccuWeather.com/Ready.