The heat is on

Summer sun certainly makes exercising outdoors more fun. But if you don't take precautions, getting physical in the heat of day can be hazardous to your health. Sweating is the body's way of staying cool during exertion; you'll sweat off from 1 to 1.5 litres of water an hour in the process. But if you don't drink enough fluids to replace what you've lost, you may expose yourself to heat injury.

The mildest type of heat injury is heat cramps – when your muscles cramp up painfully from losing too much salt and not drinking enough fluids while exercising. As soon as you notice cramping, move to the shade or a cool area and have something to drink. Either salted water (¼ to ½ teaspoon of salt per litre of water) or a sports drink that contains electrolytes will do (make sure you get a sports drink and not an energy drink). Massage and stretch your cramped muscles and you should feel better soon.

Heat exhaustion is a more serious condition, brought on by sweating heavily, along with not getting enough fluids. The body can't deliver enough blood to the brain, skin, and muscles, leading to dizziness, weakness, and fainting.

If the body becomes dehydrated (runs out of fluids), you can end up with life-threatening heat stroke, which can show up suddenly. As the sweating mechanism shuts down, the skin becomes hot and dry, and the body temperature soars, leading to convulsions and permanent brain damage.

If you think someone is suffering from one of these heat injuries, get medical help right away. Meanwhile, move the victim to a shaded area, take off extra layers of clothes, wet and fan the body, and raise the person's legs and buttocks. Make sure to provide him or her with as much water to drink as possible.

Here are some tips to help you avoid heat injury in the first place:

  • Drink plenty of fluids while you're exercising – whether you're thirsty or not. Before, during, and after the activity, aim for roughly a cup every half-hour. You can also consider drinking salted water or a sports drink if you are sweating a lot.
  • To help your body cope with the heat and humidity, get into shape before the season.
  • Don't overexert yourself in hot weather – take a lot of breaks. This is especially true if you've only recently taken up a sport or a particular exercise; your body's more likely to feel the extra stress. 
  • Schedule your sports for the coolest parts of the day, either morning or late afternoon. The sun's rays are strongest between 10 a.m. and 4 p.m. Better yet, exercise indoors in an air-conditioned gym. 
  • Exercise at a slower pace. Working out for a shorter time, but more intensely, won't protect you from heat injury. 
  • Dress for the weather. Wear lightweight, breathable, light-coloured clothes. And don't forget to protect your head, eyes, and skin: wear a hat and sunglasses, and make liberal use of sunscreen.

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