Spinal cord injury results in the inability to walk due to paralysis of the leg muscles. Because of loss of leg function, the ability to maintain normal levels of physical activity is severely impaired, with persons becoming wheelchair-dependent to get around their home or the community. Associated with this dramatic decrease in activity level, there are several changes that take place in the body: rapid gain of fat tissue and loss of muscle mass, reduction in physical fitness, decrease in the inability to normally regulate the heart and blood vessels, and severe difficulty in moving one's bowels. These physical impairments limit social and professional activities, adversely impacting the quality of life.

Thanks in large part to technological advances, there are new options to permit upright walking for persons with leg paralysis. Termed powered exoskeletal systems, these systems support the paralyzed individual through motorized bracing of the feet, ankles, legs, pelvis, and lower trunk. The operator of this apparatus is required to use crutches or a walker for balance and stability while standing, stepping, and walking. Over-ground ambulation is accomplished with appropriate weight shifts by the user, computer signals, and powered motors at the hip and knee joints. To walk over ground, the operator must actively place his or her body appropriately in preparation for the next step. The process of walking is an action of leaning forward, losing and then regaining balance, very similar to that of a toddler learning to walk. The execution of this pattern of movement places demands on the neuromuscular and sensory systems of the user, but this is a good thing because there is potential for improvement in these systems.

Because the use of this walking technology has been fairly recently developed for use by those with spinal cord injury, some of the most basic aspects of its application have not yet been measured. Thus, the primary objectives of this work are to document how long it will take to reach specific functional gains, such as speed and distance after 36 sessions of training with these devices. As such, because of increased activity of maintaining upright posture and the actual maneuver of walking in the exoskeleton, it is possible that there will be beneficial changes to body composition and the ability to move one's bowels. The preliminary studies by the investigators to date support the goals that walking in the exoskeletons will improve bowel function and body composition. It may also be anticipated, although not yet proven, that other positive changes will occur due to increased physical activity and loss of body fat; these other potential benefits include an improved blood cholesterol profile (e.g., higher HDL, or "good," cholesterol), better cardiovascular function, an increased sensitivity of the body to the actions of insulin, and an improvement in certain sex hormones (testosterone and estrogen levels), which can favorably influence muscle, fat, and bone. Therefore, it is hoped that the physical activity of standing and walking with these exoskeletal devices would lead to favorable changes in one's body composition and health and therefore would be expected to result in a better quality of life.

This research will take place at three centers that are working together on this project. They are the James J. Peters VA Medical Center in the Bronx, NY, the Kessler Foundation Research Center in West Orange, NJ, and the University of Maryland Rehabilitation and Orthopaedic Institute in Baltimore, MD. We will enroll up to 64 volunteers over a 4-year period. In order to qualify for the study, individuals must be 18 to 65 years old with a history of spinal cord injury at least 6 months ago. Participants will need to commit to a 6-month long study. Half of the enrolled volunteers will first be enrolled in exoskeletal walking training three times per week for 12 weeks, and the other half will be observed doing their usual activities for the same 12-week period. The volunteers will then be switched so that the usual activity group will have an opportunity to do exoskeletal walking. Walking ability as well as assessment of body composition, bowel function, medical health, and surveys for assessment of quality of life will be assessed at various time points during the study including the start, at the switch-over point, and at the study end.

Our proposed study will generate information for caregivers and their patients concerning exoskeletons that define the time commitment it takes to reach clinically relevant milestones for meaningful functional gain. If training in an exoskeleton is demonstrated to improve the health of those with chronic spinal cord injury, this may provide the impetus to change the basic approach of professionals caring for those with spinal cord injury, as well as to influence third-party (insurance) reimbursement decisions regarding use of this novel apparatus. Users of the exoskeletal devices, regardless of level of lesion, will potentially gain mobility and may be anticipated to have associated health benefits, all of which could translate into an improved quality of life.