FRIDAY, July 22 (HealthDay News) -- With temperatures soaring across much of the United States, people should use caution when engaging in aerobic activity outdoors or in facilities without air conditioning, the American Council on Exercise warns.

Dr. Cedric X. Bryant, the council's chief science officer, offered the following guidelines for avoiding heat-related injuries when working out in hot, humid conditions:

• Drink water. Consume a large amount of water 30 minutes before exercise and at least six ounces every 20 minutes during a workout. Once finished exercising, continue drinking water even after you are no longer thirsty. If exercising for more than 60 minutes, you may substitute a sports drink for water.
• Get your body accustomed to the heat. It takes up to two weeks of combined heat exposure and exercise for your body to acclimatize to the environment. Once your body has adapted, you will sweat sooner, sweat more, and lose fewer electrolytes through sweat, resulting in a lower body core temperature, a decreased heart rate response to exercise, and lower potential for dehydration and electrolyte depletion.
• Slow down. Lowering the intensity level of your workout will reduce the strain on your body and improve its ability to regulate temperature.
• Dress right. Don't wear waterproof clothes. These fabrics will prevent the evaporation of sweat from the skin and increase the risk of heat injury.
• Be smart. Temperature and heat can significantly affect your body's ability to respond to heat stress. Consider cutting back on exercise when the temperature rises above 90 degrees Fahrenheit and relative humidity is above 60 percent.

More information

The U.S. Centers for Disease Control and Prevention provides more tips on how to prevent heat-related illnesses.