The FDA classifies Gatorade as a low sodium beverage. Sodium plays a key factor in maintaining fluid balance and is essential for rapid fluid absorption. Gatorade is formulated with 110 mg of sodium per 8oz to help replace lost fluids and restore fluid balance. However, less sodium in a rehydration drink is less effective in replacing what you lose in sweat. It contains no caffeine or carbonation, which are the last things you want in a rehydration beverage.
Carbonation inhibits drinking and can cause throat burn and stomach bloating.
Caffeine and alcohol impair rehydration by promoting urine production and fluid loss.