Creatine but not betaine supplementation increases muscle phosphorylcreatine content and strength performance - Favero, Serena del; Roschel, Hamilton; Artioli, G. G; Ugrinowitsch, Carlos; Tricoli, Valmor Alberto Augusto; Costa, André; Barroso, Renato; Negrelli, Ana Lua; Otaduy, Maria Concepción; Leite, Cláudia da Costa; Lancha Junior, Antonio Herbert; Gualano, Bruno (Amino Acids, 2012)