Cat. No.: H128-1/10-629E
HC Pub.: 110001
Being physically active provides many health benefits, but during extreme heat it can put you at risk even if you are healthy.
Your risk increases if you have:
If you are taking medication or have a health condition, ask your doctor or pharmacist if it increases your health risk in the heat and follow their recommendations.
Heat illnesses can lead to long-term health problems and even death. These illnesses include heat stroke, heat exhaustion, heat fainting, heat edema (swelling of hands, feet and ankles), heat rash and heat cramps (muscle cramps) and are mainly caused by over-exposure to extreme heat or over-exertion for a person's age and physical condition.
Your body produces heat, especially during physical activity. Hot air and exposure to direct sun rays or hot surfaces also heat your body. This heat is lost by contact with cool air and by sweat production which cools your body as it evaporates. Weather conditions play a big role in how your body regulates its temperature. For example, if it's windy, sweat evaporates faster, which helps to cool you. However, high humidity slows down this process, contributing to increased body temperature.
Your body is not used to (not acclimatized to) extreme heat at the beginning of the summer. You are also not acclimatized if you don't exercise regularly during hot weather.
Protect your health - watch for symptoms of heat illness, which include:
If you experience any of these symptoms during extreme heat, immediately move to a cool place and drink liquids. Water is best.
Heat stroke is a medical emergency! Call 911 or your local emergency number immediately if you are caring for someone, such as a running partner, who has a high body temperature and is either unconscious or confused.
While waiting for help - cool the person right away by:
Never leave people or pets in your care inside a parked vehicle or in direct sunlight.
Drink plenty of cool liquids, especially water, before you feel thirsty. Thirst is not a good indicator of dehydration. By the time you feel thirsty, you are already dehydrated.
If you can, reschedule strenuous outdoor activity to a cooler part of the day or another day. There are also many ways in which you can still be physically active while avoiding the heat, such as:
Before heading out, check the Air Quality Health Index (AQHI) in your area, if available - air pollution tends to be higher during extreme heat. When active, you are more sensitive to air pollution because you breathe deeply and allow more air to enter your lungs.
If you are in an area where mosquitoes are active, protect yourself with insect repellent and follow the manufacturer's directions.
Try not to expect the usual performance from yourself during extreme heat.
Move into the shade, drink water and remove gear such as a helmet or equipment to let your body cool off.
Exposure to direct sun will heat your body and can result in sunburn. Sunburned skin loses its sweating efficiency, which impairs your body's ability to regulate its temperature.
Allow your body to recover after heat exposure. Spend a few hours in a cooler tree-shaded area or somewhere that's air conditioned, such as your home, a shopping mall, grocery store, public building or public library.