Exercise and multiple sclerosis.

Multiple sclerosis (MS) is a neurological disease characterized by a variety of potentially debilitating symptoms. The manner in which the disease affects each individual is unique; however, many individuals with MS have a normal life expectancy and remain ambulatory throughout their lives. Very little research has focused on understanding how MS affects basic physiologic responses during exercise. Four general topics have been addressed: autonomic control of heart rate (HR) and arterial blood pressure (BP), cardiorespiratory fitness, skeletal muscle function, and symptom instability under thermal stress. Abnormalities in cardiovascular reflexes have been observed in some MS individuals during quiescent testing; however, HR and BP responses during exercise have not confirmed such findings. Deficits in cardio-respiratory fitness appear to be present in moderately impaired individuals, which are not always present in minimally impaired persons. Similarly, abnormalities in skeletal muscle function have been reported in some individuals with MS, while absent in others. Training appears to improve both cardiorespiratory fitness and skeletal muscle function. Findings appear to be indirectly influenced by the level of physical impairment of the experimental sample. This factor needs to be considered in sample selection, as well as in analyzing and reporting data. Elicitation of symptoms in response to thermal stressors has been documented by several investigators using unreliable techniques to measure core temperature. The use of more valid methods during rest and exercise have not confirmed the relationship between symptoms and core temperature changes. It may be that thermal sensitivity, although typically reported by most MS individuals, is a symptom that is very unique to each individual and sample selection may have indirectly contaminated results in past research. Considerations for future research are discussed.