Multiple sclerosis is defined as a "degenerative inflammatory disease of the central nervous system, involving the brain, optic nerve, and spinal cord"(Brawner & Schairer, 2000). Classically, it has been described as "space and time," where dispersed areas of the central nervous system cause exacerbations and remissions over time (Brawner & Schairer, 2000). The name "multiple sclerosis" is derived from the Greek word sklerosis, meaning "hardening," where scar tissue replaces disintegrating myelin and leads to white matter in the brain and spinal cord, of sizes of a pinpoint to one centimeter in diameter (Boss & Farley, 2000). The demyelination along the central nervous system leads to less controlled and coordinated movements. Autonomic nervous system abnormalities become present in heart rate and blood pressure response (Brawner & Schairer, 2000).
Multiple sclerosis is a chronic, inflammatory disease that affects the central nervous system and causes gradual destruction of myelin (demyelination) and transection of neuron axons patches throughout the brain and spinal cord. Myelin, the fatty material surrounding the nerves, is destroyed, leading to symptoms, such as muscle weakness/paresis/paralysis, spasticity/tremor, and impaired balance, lack of coordination, heat sensitivity, and fatigue. Though multiple sclerosis can be a challenging health condition both physically and psychologically, research has shown that a person's level of physical fitness, psychological disposition and general quality of life can improve with regular physical activity, strength training, and flexibility exercises.