People with spinal cord injuries may experience muscle tightness or uncontrollable spasms. This study is being conducted to investigate whether transcutaneous spinal stimulation can improve these symptoms. Transcutaneous spinal stimulation is a non-surgical intervention by applying electrical currents using skin electrodes over the lower back and belly. The investigators want to see how well the intervention of transcutaneous spinal stimulation performs by testing different levels of stimulation pulse rates. Also, transcutaneous spinal stimulation is compared to muscle relaxants such as baclofen and tizanidine, commonly given to people with spinal cord injuries, to reduce muscle stiffness and spasms. By doing this, the investigators hope to discover if transcutaneous spinal stimulation similarly reduces muscle spasms and stiffness or if combining both methods works best. This could help improve treatment options for people with spinal cord injuries in the future.