Spinal cord injury (SCI) occurs at an annual rate of 50-60 per million in North America. Paralysis is also accompanied by drastic changes in independence and quality of life. SCI occurs mostly among younger individuals, half in people 16-30 years of age. Two-thirds of all SCIs are incomplete (iSCI), with some preserved neural connections relaying information to and from the brain. People with iSCI benefit most from improvements in walking. In addition to increasing independence, walking helps persons with iSCI remain active, with a variety of beneficial health-related outcomes. Therapy that can significantly increase sensorimotor function to these individuals living with iSCI for multiple decades would be hugely significant.~Currently, the most common strategies for restoring walking after an iSCI are manually intensive, including over ground walking with weight and balance support provided by multiple therapists, or with the use of expensive robotic support with controversial outcomes. Thus, the overarching goal of this proposal is to investigate if a non-specific gait rehabilitation paradigm based on motor-assisted arms and legs cycling in AIS C and D iSCI individuals generalizes to improvements in walking that outperform conventional gait specific training (Specific Aim 1). The researchers will also investigate biomechanical and motor coordination changes and adaptations tied to these functional improvements (Specific Aim 2), and the neural mechanisms that explain functional improvements and their retention over time (Specific Aim 3).~Specifically, in Specific Aim 1 the researchers will investigate the clinically-relevant gait improvements afforded by the cycling intervention. In Specific Aim 2 the researchers will focus on studying the detailed biomechanical basis for the gait improvements. In Specific Aim 3 the researchers will investigate the neuroplastic mechanisms underlying the gait improvements. For these Aims, the researchers will measure the walking gains with a battery of standard clinical tests focused on motor function, sensation, balance and spasticity (Specific Aim 1). The researchers will use motion tracking, force plates, and EMG measurement to monitor the kinematics and kinetics of gait, the neuromuscular coordination, and oxygen consumption as a measure of these energetics of walking (Specific Aim 2). In addition, the researchers will conduct a battery of physiological tests at 3-week intervals intended to detect changes in the strength of descending and ascending spinal pathways (Specific Aim 3).
The purpose of this study is to examine the ability of simultaneous motorized upper and lower extremity cycling training to regulate spinal movement patterns in order to potentially restore functional abilities (i.e., walking) in individuals with an incomplete spinal cord injury. The researchers hypothesize there will be improved walking function following motorized cycling.