Spinal cord injury (SCI) produces bone, muscle, and neural impairments that increase fracture risk and impede recovery of physical function. Locomotor training (LT) increases muscle size and promotes recovery of muscle function and walking in some persons with incomplete SCI. It is unknown if testosterone replacement therapy (TRT) improves these factors in men who have walking dysfunction and low testosterone after incomplete SCI. In addition, the combined effects of LT plus TRT remain unknown in men with incomplete SCI.~For this pilot study, men with chronic incomplete SCI involving spinal level L1 or above or complete SCI involving spinal levels T2-L1, with upper motor neuron signs, who have low testosterone and walking dysfunction will receive 6-months of TRT alone or TRT with LT. TRT injections will be given weekly. LT will involve 35 sessions of treadmill walking with assistance and overground walking (4 sessions per week) during the initial 2-3 months of TRT. Participants will be assessed at study entry and at 1-6 month intervals thereafter. Testing will include measurements such as a magnetic resonance imaging (MRI) scans, dual energy x-ray absorptiometry (DEXA) scan, and muscle performance and walking tests. Participants will also undergo safety tests, including physical exams, electrocardiogram (ECG), prostate digital rectal exam, and blood tests to assess hematocrit, liver enzymes (AST and ALT), prostate specific antigen (PSA), and other health markers. The treatment groups will be compared with a non-treatment control group comprised of men with incomplete or complete SCI who receive no treatment. Participants enrolled in the non-treatment control group will undergo the same tests described above.
This pilot study will determine the feasibility of implementing a combinatory rehabilitation strategy involving testosterone replacement therapy (TRT) with locomotor training (LT; walking on a treadmill with assistance and overground walking) in men with testosterone deficiency and walking dysfunction after incomplete or complete spinal cord injury. The investigators hypothesize that LT+TRT treatment will improve muscle size and bone mineral density in men with low T and ambulatory dysfunction after incomplete or complete SCI, along with muscle fundtion and walking recovery in men with T low and ambulatory dysfunction ater incomplete SCI.