The aim of this study is to understand what happens to muscle and bone in spinal cord injured males after four months of training using stand training, with body weight support (BWS), with testosterone replacement therapy (TRT), and electrical stimulation (ES). Specifically, researchers will investigate nerve, muscle, and bone changes in the lower limbs in response to stand training and ES when combined with TRT compared to i) standing alone with TRT; ii) stand training alone with placebo; iii) stand training alone and ES with placebo.