#$%^&*AU2015203791B220170629.pdf#####ABSTRACT A method and compound for treating skeletal muscle mass deficiency in a human subject, comprising antisense compounds with morphorlino subunits that hybridize to myostatin. The treatment aims to return myostatin levels to within a healthy range, as measured by determining the level of heteroduplexs comprising the antisense compound in a sample of subject body fluid.