Do you really need sports drinks when exercising? Sure, it's important to replenish lost fluids during exercise, but good old H2O will generally work just fine.
Though they certainly won't hurt you, there's really no need to use sports drinks unless you exercise vigorously for a prolonged period of time. If you do, you'll lose sodium and potassium which sports drinks will replace. Otherwise, just drink water, but be sure to drink enough.
A 45-minute exercise session demands 2-3 cups two hours before, 1-2 cups just before and 8 ounces every 20 minutes or so while exercising. After exercising, drink what you need to quench your thirst.
See your Fitness USA instructor if you have any questions.