There is provided novel amino acid ester compounds comprising at least one nitric oxide releasing group and pharmaceutically acceptable salts thereof, and novel compositions comprising at least one amino acid ester compound comprising at least one nitric oxide releasing group, and, optionally, at least one nitric oxide donor and/or at least one therapeutic agent. Also provided are compositions for increasing nitric oxide physiological levels in a subject, methods for increasing nitric oxide physiological levels in a subject, methods for improving a subject's muscle strength, athletic performances and/or lean body mass gain and or performance in a subject.