The problem is every time you pee, sweat, or breathe with your mouth open, you lose potassium amongst other electrolytes. So if you're exercising you're doing at least 2 of the 3 and your body can't replace the electrolytes fast enough to compensate. OTHO: if you're not experiencing any problems like leg cramps or extreme fatigue and are recovering ok, as always, go with what works for you.