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A study from New Zealand shows that women who drank a salty solution before exercising in hot weather retained more fluid and were able to exercise longer in hot weather (Journal of Applied Physiology, August 2007). Almost two hours before exercising, trained female cyclists started to drink a salty solution and continued to take this solution six more times over an hour.
They took no fluid during their endurance trial. The salty drink caused their bodies to retain extra fluid before exercising and helped them to exercise much longer and harder than when they took no pre-exercise salty drink. The female hormone, estrogen, causes salt retention, but their performances were not affected by taking birth control pills, a source of estrogen, or at specific times during their menstrual cycles.
Most people object to the taste of salty drinks, so it may be more practical to drink water or the beverage that tastes best to you, and eat salted foods such as peanuts, chips or crackers.