That's what I was thinking runin. 60-80 ounces isn't that much, I'd call that moderate. Hyponitremia, too little electrolytes, could cause the twitching. Water, or plasma, itself doesn't conduct electricity very well- that's why you add you need an electrolyte, like hydrochloric or sulfuric acid in batteries. If you're low on electrolytes the message doesn't get across correctly so things start to misfire. I get most of my electrolytes from V8 (high in sodium and potassium) since I'm not much of a sports drink guy. If you don't eat much sodium or get much potassium from fruits and vegetables, consider a sports drink and see if it helps.