Should I drink water when I exercise, or not?

When you exercise hard or in hot weather, you sweat and breathe off huge amounts of fluid. Losing fluid reduces blood volume to make you tired. Anyone who exercises vigorously can increase their endurance by taking in fluids, and competitive athletes can increase their endurance by taking in extra fluids just before the start of their event and drinking fluids regularly during events that last more than an hour. Be sure to replace salt as well as fluid you lose when you sweat. Don’t force yourself to drink large amounts of water.

A study presented at the Experimental Biology meeting in San Diego (April 11-15, 2003) demonstrated that drinking water helps athletes to exercise longer. Ten college students drank four, eight or 12 eight-ounce glasses of water per day for 12 weeks. On four glasses of water per day, they had five percent lower blood volume than on eight glasses, and ten percent lower that on 12 glasses. Lowered blood volume should not effect non-exercisers, but regular exercisers can increase their endurance by drinking more fluids.

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