5-HD, 5-hydroxydecanoate; AgF, aged female rats; CICUAL, Institutional Committee for Care of Laboratory Animals; CONICET, National Council of Scientific and Technical Research; Calcium; Cardiomyocytes; DAZ, daidzein; DMSO, dimethylsulphoxide; Daidzein; F, Fisher coefficient for variance statistical test; HPLC, high performance liquid chromatography; Ht, total heat rate; I/R, ischemia and reperfusion; ISOF, soy isoflavones; Isoflavones; MACA, Lepidium meyenii root powder; Maca; Mitochondria; Myocardial economy; NOS; NOS, nitric oxide synthases; P, maximal pressure developed in contraction; P/Ht, muscle economy; PICR, post-ischemic contractile recovery; PKC, protein-kinase C; ROS, reactive oxygen species; SEM, standard error of media; TFT, triphenyltetrazolium chloride; YF, young female rats; YM, young male; i.p, intraperitoneal; l-NAME, Nω-nitro-l-arginine methyl ester hydrochloride; mKATP channels; mKATP, mitochondrial ATP-dependent K+ channels; mNCX; mNCX, mitochondrial Na/Ca exchanger; ΔLVEDP, resting diastolic pressure