A somewhat controversial/unproven supplement is creatinine monohydrate, an ergogenic. It usually comes from both our diet and our body's own production. Creatinine is produced in our body's liver, pancreas and kidneys and is part of our body's energy cycle.
Creatinine Monhydrate is claimed to increase our intramuscular levels of creatinine phosphate, a high energy compound. It figures into the high-energy phosphate (ATP) used in most metabolic reactions in voluntary as well as involuntary movement.
Muscle builders use this to build bulk in muscles as well as to make them lift still heavier weights. Aerobic athletes such as runners or bike riders benefit as well. However, in the normal individual, it can aid in work-outs, helping a person not only look, but perform better muscularly.
It can help to take 5 to 15gm a day as a supplement.
It is claimed to be without side-effects, although at the time of writing no long-term studies have been carried out. It can cause muscle cramping, which is easily combated by taking some extra magnesium.