Staying Hydrated

During the summer heat, dehydration is inevitable. You are going to sweat. And performance starts to decline when you lose as little as 3% of your body weight in sweat. For a 150 pound person, that is about 4.5 pounds. At 15 to 20%, it can become life threatening.

Test your loss by weighing yourself (without clothes and shoes) before and after several runs. Each pound you loose, is about 16oz. of fluid loss. So if you sweat of a pound in 30 minutes of running, you should be drinking at least 16oz of fluid during the run. 

Drink plenty before the exercise. Never start a race dehydrated. For longer events, use sports drinks to replace the carbohydrates and electrolytes. Don't wait until you are thirsty to drink. Thirst is a sign of dehydration. Replace any loss quickly after the event. Watch for any signs of heat exhaustion or heat stroke. STOP - find shade and drink! Beware of hyponatremia. You loose a lot of sodium through sweat and replacing it with plain water can dilute the sodium level in your blood, which can set off an electrolyte imbalance. In severe cases this can be very serious.

 Just be careful.