People with spinal cord injury have impaired movements of their arms and/or legs, due to paralyzed muscles. However, when we externally stimulate those muscles using electrical stimulation, muscles can be made to contract to generate different limb movements and physical activities such as walking, standing, and grasping. People with spinal cord injury can also use electrical muscle stimulation to train muscles and maintain muscle strength, which will in turn prevent other complications such as pressure sores, low-impact fractures, and deep vein thrombosis from occurring. Thus, rehabilitation using electrical muscle stimulation is very advantageous for this patient population.
However, one aspect that often limits the use of electrical stimulation is the rapid onset of muscle fatigue. One can potentially explain the muscle fatigue following electrical stimulation by the fact that electrical stimulation contracts muscle fibers simultaneously and that electrical stimulation is unable to contract all the fibers within the muscle.
In the current project, we propose a new stimulation method that would activate most of the muscle fibers in a regulated cyclic pattern. To achieve this, we will use special electrodes to distribute the stimulation centre over a larger area of skin. The advantage of the new stimulation approach is that it is easy to use with the present functional electrical stimulators. Direct benefits of this stimulation technique for patients include reducing muscle fatigue and therefore allowing patients to remain engaged in therapy for a longer duration. This technique has a potential to help individuals with spinal cord injury use electrical stimulators more effectively either as a permanent orthosis to substitute for a compromised neuromuscular function, or as a muscle strengthening therapy, both of which have been found to be beneficial for individuals with spinal cord injury.