Creatine
 

Science has established that supplementation with creatine monohydrate increases muscle size and strength during resistance training. These beneficial effects are thought to occur via the accumulation of creatine in muscle cells which appears to increase phosphocreatine stores in muscle. Phosphocreatine is the primary energy substrate used to regenerate ATP (the biological currency of energy in working muscles). Therefore, boosting phosphocreatine stores with creatine may allow for greater amount of work performed during individual training sessions and a more powerful growth stimulus. However, a recent study has shown that creatine monohydrate may enhance energy production in other ways.

Canadian researchers have discovered that supplementation with creatine monohydrate in rodents increased the aerobic breakdown of glucose and reduced the production of lactic acid. Aerobic means requirement of oxygen. The aerobic energy production pathway is the major pathway of energy metabolism that produces the largest amounts of ATP. The accumulation of lactic acid in working muscle is the by-product of energy metabolism without oxygen and is a major cause of fatigue and muscle failure.

Therefore creatine monohydrate supplementation may enhance energy production in working muscles in more ways than previously suspected. Supplementation with creatine may enhance phosphocreatine stores and boost aerobic energy production. However, remember that this study used Creatine monohydrate, not creatine-ester which does not have any scientific evidence of its effectiveness.

lol ester worked for me thought, im not sure which i like better though esterfied or monohydrate