Heat and humidity are on the rise, and while the weather invites people to exercise outdoors, it’s important to understand how to safely work out in warmer climates. According to the Centers for Disease Control and Prevention, an average of 702 heat-related deaths and 67,512 emergency department visits occur each year in the United States. With hot weather putting extra stress on the body, Exercise and Movement Science program director Jason Sawyer, Ph.D., offers recommendations for how people can make smart health decisions while engaging in effective workout sessions during the summer months. 
 
Choose morning or evening workouts 

For those who are new to exercising or used to training in a thermoneutral environment, the body needs seven to 14 days to adjust to exercising in the heat.

“You can exercise in the heat in small doses before that, but it’s really about listening to your body, making sure you allow for appropriate recovery, and dressing in loose and lightweight clothing,” says Sawyer. 

Exercisers should avoid working out between 11 a.m. and 2 p.m., which are the hottest hours of the day; instead, early morning or late evening training sessions offer cooler and potentially less humid alternatives.

“What we really want to avoid is hot, humid climates because that decreases our ability to evaporate sweat off of our skin, which is what cools us down,” Sawyer says, adding that people should be aware of their solar load and should wear sunblock.  
 
Drink plenty of liquids 

Staying hydrated is essential, especially when people may begin a workout slightly dehydrated.  

“A person wants to drink 16 to 24 ounces for every pound of sweat they lose,” Sawyer says. “If you weigh yourself before and after exercising, you want to make sure that you are consuming enough fluids.” 

For those exercising for an hour or less, Sawyer recommends drinking water; however, individuals who are training for more than an hour may also want to consume an electrolyte-based drink, such as Gatorade or Powerade. Electrolytes can help people maintain a healthy fluid balance and avoid an imbalance that could result in dehydration. Sawyer notes that people who sweat heavily or exercise for an hour or less on a hot and humid day may also benefit from consuming an electrolyte-based drink. 
 
Listen to your body 

Checking in with how you feel is important when exercising in the heat. According to Sawyer, there are three heat-related illnesses people should be aware of. 

The first — and least severe of the three — is heat cramps. These muscle spasms are caused by rapid water and electrolyte loss through perspiration and can occur in the calves, quadriceps, hamstrings and abdominals. Sawyer recommends applying pressure to the affected area and moving to a cooler spot to replace fluids as needed. 

Sawyer notes that heat exhaustion is a level up from heat cramps. Signs of this heat-related illness include heavy sweating, clammy skin, complaints of dizziness or headaches, and a fast but weak pulse.  

“During this time, you want to move into a cooler climate and consider cooling down with ice packs or a wet towel,” Sawyer says. 

The most severe of the three is heat stroke, which calls for medical response. Heat stroke occurs when the body’s internal temperature is 103 degrees or above, and warning signs include a severe headache, nausea, and display of confusion. Sawyer explains that a person’s skin will be hot and red but dry to the touch since they have stopped sweating in order to retain blood volume. 
 
Have an alternative workout plan 

The weather may not always be in an exerciser’s favor — especially during hot days where temperatures reach the high-80s and 90s. Therefore, an outdoor training session may need to be moved indoors. 

For those with access to workout equipment, Sawyer suggests running on a treadmill in an air-conditioned room or completing exercises with a kettlebell or dumbbell. Still, there are many options that require minimal equipment. 

“You can always do a high-intensity interval training (HIIT) program, which is referred to as Tabata-style workouts,” Sawyer says.  

In HIIT, individuals complete a circuit of resistance training exercises at high intensity over a short amount of time. Sawyer recommends doing one exercise for 20 seconds, followed by 10 seconds of rest. A person would then move onto the next exercise and repeat the circuit. After one set is complete, individuals take a two-minute rest break and repeat the process until they’ve completed two to four sets. Sawyer notes that individuals receive cardiovascular benefits from HIIT, and exercise templates can be found online. 

“It’s really a time efficient way of exercising,” Sawyer says, adding that the workout — not including a warmup or cool down — will take eight to 12 minutes.