The present invention generally relates to compositions and methods for treatment of subjects in need of muscle growth, muscle repair, improved muscular and neuromuscular control, and treatments for neuromuscular and neurological disorders, including brain disorders. In some cases, the composition may include nitric oxide and/or peptides such as thyrotropin-releasing hormone (TRH) and/or GnRH (gonadotropin-releasing hormone). The nitric oxide and/or peptides may be present within a first phase comprising a lecithin, such as phosphatidylcholine. In certain embodiments, the lecithin is present in liposomes, micelles, or other structures containing nitric oxide and/or peptide. The composition can take the form of a gel, a cream, a lotion, an ointment, a solution, a solid “stick,” etc., that can be rubbed or sprayed onto the skin, e.g., onto a location where muscle growth, muscle repair, or improved muscular and neuromuscular control is desired, or on another suitable portion of the skin. Other aspects of the present invention are generally directed to methods of making or using such compositions, methods of promoting such compositions, kits including such compositions, or the like.
