Though I am considered one of the more fit individuals in my very athletic circle, I sweat profusely, more than a Fin in Ecuador! Some friends have told me that this indicates an efficient physiological makeup, however, I have always associated it to obesity and lack of fitness. What is the truth about sweat?

— Michael P. Shannon, Ft. Collins, Colorado

Your friends are right. Sweating is your air conditioning system: As you exercise your body generates heat, which must be dissipated. One thing we don't tolerate well is a high body temperature, and without some form of cooling you'd chug through a few minutes of activity, then fall over dead. So your AC kicks in. It routes blood to your periphery (skin) and your sweat glands start secreting a weak saline solution (that's why it's salty). The sweat on the surface of the skin acts to cool it down by a process known as evaporative cooling, thereby lowering the temperature of the blood. The upside is you keep going, the downside can be dehydration; you can lose up to three liters of water per hour.

Just as the wonderful odors that are unjustly associated with sweat are very individual, so are sweat rates. Women, for example, tend to sweat less than men do, and you appear to have been graced with a set of over-achieving glands. Part of your sweatiness can be attributed to your level of fitness. Highly trained persons tend to sweat earlier in exercise, over a larger portion of the body and with higher sweat rates. Obese individuals may have high sweat rates but this is primarily due to an inefficient cooling system. Fat acts as an insulator, meaning these folks roast inside when they are doing even low levels of exercise and are trying to keep body temperature within reasonable limits.

With your high sweat rates you should be hydrating regularly before, during and after exercise. One of the primary limitations of athletic performance is dehydration; limit fluids coming in and your AC can't keep you cool. Use water or a fluid replacement product that has electrolytes and low levels less than seven percent concentration) of carbohydrate, preferably in the form of glucose polymers.