Creatine

Creatine, from the Greek kreas = meat, is an amino acid derivative and one of the most widely used sports supplements with the most supporting studies. Phosphorylated into phosphocreatine, it constitutes one of the muscle energy stores and is used as required during rapid and intense muscle contractions. Recommendations for its use are limited to optimal intake not on an empty stomach and for continuous periods of time, preferably in conjunction with the intake of other nutrients. Excess creatine is considered 'safe', as even if abundant, this molecule cannot be converted into fatty acids.

For intake, the literature recommends two different strategies:
1) With uniform intake: 3-5g of creatine per day;
2) With a loading phase: peak intake from 1 week to 20 days with 20g/day (to be divided into 4 daily intakes of 5g each), followed by a maintenance phase at 3-5g per day consistently.