How to stay hydrated during your workout

You should follow the same guidelines when exercising indoors. Even if the air conditioning is on, you still sweat a lot if you spend 45 minutes or more on a stepper, treadmill or stationary bike. Don’t assume you have to be outdoors for serious dehydration to occur.

Don't wait until you're thirsty to start drinking. The sensation of thirst is triggered by the hypothalamus in the brain. It measures the concentration of salts in your blood. As blood volume decreases due to sweating, your concentration of salts goes up, and the hypothalamus sends the signal to start drinking. By the time you feel thirsty, you are already dehydrated.

How can you be sure you're drinking enough water? When your urine is clear, rather than yellow, you are sufficiently hydrated. Make sure you keep drinking water after exercise. If you can weigh yourself before and after a workout, a good rule of thumb is to drink one pint of water for every pound you've lost.

Don't forget that caffeinated beverages are diuretics. These drinks make you pee and lose fluid quickly, so you’ll need an additional glass of water for each cup of coffee or fizzy drink you have. Alcohol also dehydrates you, so for every beer or vodka you enjoy, match it with a glass of water.

All of these recommendations are, of course, in addition to the eight glasses of water per day that we know you are already drinking.