Arm and Leg Cycling for Accelerated SCI Recovery

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, motor-assisted arms and legs cycling with functional electrical stimulation (FES) to the main muscles of the legs (A\&L\_FES group), or motor-assisted arms and legs cycling with FES to the main muscles of the legs and transcutaneous spinal cord stimulation (tSCS) at the cervical level (A\&L\_tSCS group) in AIS C and D iSCI individuals generalizes to improvements in walking that outperform conventional gait specific training, e.g., body-weight supported treadmill training (BWSTT; control group) (clinical assessments). The researchers will also investigate biomechanical and motor coordination changes and adaptations tied to these functional improvements (biomechanical assessments), and the neural mechanisms that explain functional improvements and their retention over time (neurophysiological assessments).

In the clinical assessments the researchers will investigate the clinically-relevant gait improvements afforded by the cycling intervention by measuring the walking gains with a battery of standard clinical tests focused on motor function, sensation, balance and spasticity. In the biomechanical assessments the researchers will focus on studying the detailed biomechanical basis for the gait improvements by using motion tracking, force plates, and EMG measurement to monitor the kinematics and kinetics of gait, and neuromuscular coordination. In the neurophysiological assessments the researchers will investigate the neuroplastic mechanisms underlying the gait improvements by conducting a battery of physiological tests to detect changes in the strength of descending and ascending spinal pathways.

• Change in 6-minute walking test (6MWT) [Time frame: Changes across baseline, after 3 weeks of training, after 6 weeks of training, after 9 weeks of training, after 12 weeks of training, and 6 months after completing training.]
• Change in balance with the Berg balance scale (BBS) [Time frame: Changes across baseline, after 6 weeks of training, after 12 weeks of training, and 6 months after completing training.]
• Change in walking ability with the WISCI [Time frame: Changes across baseline, after 6 weeks of training, after 12 weeks of training, and 6 months after completing training.]
• Change in Modified Ashworth Scale (MAS) [Time frame: Changes across baseline, after 6 weeks of training, after 12 weeks of training, and 6 months after completing training.]
• Change in step length [Time frame: Changes across baseline, after 6 weeks of training, after 12 weeks of training, and 6 months after completing training.]
• Change in step time [Time frame: Changes across baseline, after 6 weeks of training, after 12 weeks of training, and 6 months after completing training.]
• Change in double support time [Time frame: Changes across baseline, after 6 weeks of training, after 12 weeks of training, and 6 months after completing training.]
• Change in range of motion (ROM) [Time frame: Changes across baseline, after 6 weeks of training, after 12 weeks of training, and 6 months after completing training.]
• Change in joint-joint cyclogram area [Time frame: Changes across baseline, after 6 weeks of training, after 12 weeks of training, and 6 months after completing training.]
• Change in the number of muscle synergies [Time frame: Changes across baseline, after 6 weeks of training, after 12 weeks of training, and 6 months after completing training.]
• Changes in interlimb (upper-lower limb) modulation [Time frame: Changes across baseline, after 6 weeks of training, after 12 weeks of training, and 6 months after completing training.]
• Changes in the strength of cortico-spinal connectivity [Time frame: Changes across baseline, after 6 weeks of training, after 12 weeks of training, and 6 months after completing training.]