Exercise-induced hypotension in autonomic disorders

The autonomic nervous system closely integrates a range of vital processes, including, cardiovascular function. Physical activity, or exercise, requires a range of integrated autonomic and cardiovascular adjustments in order to maintain homeostasis. Pathological conditions that result in dysfunction of the autonomic nervous system, such as autonomic failure, can therefore jeopardize the control of blood pressure resulting in hypotension and have serious implications for health. Exercise induced hypotension, defined as a >= 10 mm Hg fall in systolic blood pressure during exercise, can be a significant symptom/event for autonomic failure, as well as other autonomic disorder, patients, including, Multiple System Atrophy and Spinal Cord Injury, and can reduce physical capacity, orthostatic tolerance, result in falls, complicate management and reduce quality of life. The likely mechanisms do not appear to be an altered cardiac output or active muscle vasodilation response to exercise, but rather, a lack of and/or a blunted increase in sympathetic nerve activity during exercise and/or excessive vasodilation in the splanchnic circulation. The severity of exercise induced hypotension seems to be higher during dynamic relative to static exercise. The possible management strategies for exercise induced hypotension include both non-pharmacological, e.g., reducing risk factors, and pharmacological measures, such as sympathomimetics, but studies on other pharmacological agents are limited. (C) 2012 Elsevier B.V. All rights reserved.