Injuries, Spinal Cord

Spinal cord injury (SCI) results in lower limb muscle loss, bone loss, and high fat mass that impede the recovery of physical function, increase bone fracture risk, and worsen health and quality of life. These deficits result from reduced activity after SCI and may be worsened by low testosterone, which is present in many men with SCI. In older men with low testosterone who do not have SCI, testosterone therapy (TRT) is known to increase muscle mass, muscle strength, and bone mineral density, and to reduce body fat. However, it is not known if TRT is effective in men with SCI. The purposes of this study are to determine the effectiveness of TRT in men who have low testosterone and difficulty walking after chronic motor incomplete SCI and to assess whether a process in the body that changes testosterone to dihydrotestosterone (DHT; another hormone that is stronger than testosterone) impacts the effectiveness of TRT in the impaired lower limbs and in other tissues after SCI. The researchers hypothesize that TRT will improve muscle and bone in the impaired limbs of men with chronic incomplete SCI and reduce fat mass, and that finasteride (a drug that blocks that blocks a process that changes testosterone to DHT) will influence prostate symptoms but not the musculoskeletal or body composition benefits produced by TRT.

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.