* Dont drink too much. Over-hydration (excess fluid intake) is becoming a serious problem because most endurance athletes believe that dehydration is their biggest enemy. However, there have been many hospitalizations and even deaths of marathon runners caused by over-hydration. The death of a female runner in the March 2002 Boston Marathon proved to be from hyponatremia (a diminished amount of sodium in the blood) caused by over-hydration. The same cause was attributed to the death of a Colorado woman who ran the 1998 Chicago Marathon. Signs to watch for include a severe headache, bloating, puffiness from water retention (i.e. tight shoes, rings, and watches), confusion, and seizures. To prevent over-hydration, it is important not to drink more than you sweat and urinate. In addition, eating a sodium-rich diet in the days leading up to a strenuous endurance activity should allow you to retain fluids more efficiently.