How to avoid passing out in the heat


As Canadians, we often spend all winter complaining about the cold, then when summer finally comes, we complain about the heat (or the humidity)! Regardless of those complaints, we know that most Canadians are more physically active in the summertime. With the dog days of summer upon us, we have to watch out for heat-related illnesses.

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Our bodies use various techniques to dispel heat. One technique is blood vessel expansion in the skin, called “vasodilation.” This means that warm blood is brought to the surface of the skin, and radiation of heat from that blood through the skin cools the body. But when you’re dehydrated, vasodilation in the lower body can lead to fainting.

Another technique is sweating. The evaporation of sweat from the surface of the skin cools the skin, bringing down the body’s temperature. But too much sweating can lead to dehydration and a critical loss of dissolved salts in the blood. When exercising in the heat, replacing fluids, particularly with something that contains some salts, like most sports drinks, is better than drinking just plain water. If the fluid or salts aren’t replaced adequately, muscle cramping can result.

As the body continues to warm up despite these natural cooling techniques, the heart can begin to beat too quickly, and blood pressure can start to drop. This can lead to dizziness or lightheadedness. The brain starts to malfunction, and you could develop a terrible headache, or become disoriented or confused. Vomiting and diarrhoea can also occur.

It’s when you stop sweating that things are really dangerous. This means that the body is so dehydrated that it can’t make sweat in order to cool off anymore. This is usually a late stage sign of heat illness and is called heat stroke. The person suffering heat stroke may be agitated, hysterical, or may even become comatose. This is a medical emergency.

The best ways to avoid heat-related illness are:

Watch the weather forecast, especially for extreme heat warnings, and avoid exercising outdoors when these warnings are issued.

Reduce your outdoor exercise time on hot days, or take frequent breaks to get into the shade.
Drink lots of fluids, prior to an during exercise, especially ones with salts, like most sports drinks. Avoid alcohol and caffeine, as these can worsen some of the symptoms and signs of heat illness.

Wear loose-fitting, light coloured clothing that allows wicking away of moisture and reflection of heat. Wear performance man-made fabrics as opposed to cotton.

Exercise with a friend. Since confusion is one sign of heat illness, you yourself may not know you’re suffering from a heat illness, but your friend may see the signs, and call for help. Always keep a cell phone with you.

Have a safe summer, and enjoy the heat!