The lipid-carrying function of carnitine has already been discussed. However, this amino acid/vitamin also has an anabolic function: if taken immediately before a bodybuilding session, in quantities of 2g, over a period of 21 days, it can increase the amount of testosterone receptors on the membranes of muscle cells (in the reference study, the chemical form was L-carnitine-L-tartrate). This effect results in an increase in muscle mass (and strength).