The advertising says the sports drinks replace the electrolytes in sweat, so I looked that up. The concentration of Powerade and Gatorade seem to be about half that of sweat. That is not a problem for me since I believe people need to replace their water at a faster rate than they sweat it out. Meaning that water also leaves by respiration and by urination.
Composition of Sweat
Na 0.9g/L
K 0.2 g/L
Ca 0.15 g/L
Mg 0.0013 g/L
Powerade zero has
Na 0.41g/L
K 0.0907 g/L
The chart at right gives numbers from First Endurance, who makes a sports drink give similar numbers for sweat, and argues for a salt heavy beverage.
Sweat has many other ingredients like ascorbic acid (vitamin C, chloride ion, lactate, urea, creatine and uric acid). Link
Lactate was
