Creatine probably does not increase your risk of renal failure. These reports were generated from the fact that a large protein load increases glomerular filtration pressure and rate. Conversely, we know that progressive kidney damage can occur in people with PRIOR renal dysfunction where there has been nephron dropout. Forcing a high filtration strain on the remaining glomeruli has been shown to accelerate renal failure (MDRD study) Hence, the false logic. There have been no credible studies showing that a high protein (or creatine) diet cause problems in patients with normal renal function.
Creatine is probably the only supplement I can think of that actually does work. There is no liver association, and the liver never even sees or handles it. Creatine is the high energy phosphate bond donor in the muscle, which provides immediate energy for muscle contraction.
The KEY function of Creatine is to allow you to work out harder than you otherwise would be capable of. This is good news and bad news. While it increases the efficiency of muscle contraction (and therefore your workout), it also pushes these fibers overboard and you end up being sore as hell the next day. Sometimes, serious injuries can occur. It would not be applicable to motocross/SX, but would be for strength weight lifting, football, etc.
