Creatine monohydrate is the most studied form of creatine. No other form of creatine has a through body of research demonstrating its positive effects for bodybuilders and athletes. Also, hundreds of studies conducted on thousands of research subjects using this form of creatine have demonstrated that it does not cause any negative side effects - no unwanted water retention, bloating, cramps, etc. Creatine monohydrate has however been proven in hundreds of studies to increase muscle size and strength and to improve performance during repeated bouts of high-intensity exercise.