Abstract:

The systemic health benefits of regular skeletal muscle activity are well documented. Increased skeletal muscle activity is associated with an improved systemic metabolic rate, reduced incidence of diabetes and obesity, and improved function with age. Despite these known systemic benefits, many healthy people do not meet the recommended daily dose of skeletal muscle activity (exercise) needed to prevent metabolic disease. People with central nervous system (CNS) damage (from complete spinal cord injury, for example), are even further compromised as they are unable to activate their own musculature. In this perspective paper, we discuss recent findings relating skeletal muscle activity and CNS signaling. A central theme is that appropriately prescribed skeletal muscle activity (rehabilitation) may have important implications for optimizing neural plasticity, enhancing stem cell proliferation and differentiation, and improving the overall environment for regenerative approaches for people with CNS damage (spinal cord injury, stroke, multiple sclerosis, closed cranial trauma, etc.). One method to induce skeletal muscle activity in people with paralysis is by activating the skeletal muscle electrically. Neuromuscular electrical stimulation directly activates peripheral nerves (not muscle), which consist of the motor and sensory axons that communicate with the muscle from the spinal cord. Most people with traumatic spinal cord injury, for example, have an upper motor neuron injury. A complete upper motor neuron injury prevents any voluntary signal from the motor cortex to the muscle; but the lower motor neuron and its associated axons are retained, allowing peripheral communication between the spinal cord and the muscle.