These findings demonstrate that exercise training in heart failure patients results in dramatic reductions in directly recorded resting sympathetic nerve activity. In fact, MSNA was no longer greater than in trained, healthy controls.

Abstract-The effects of exercise training on baroreflex control of sympathetic nerve activity in human hypertension are unknown. We hypothesized that exercise training would improve baroreflex control of muscle sympathetic nerve activity (MSNA) and heart rate (HR) in patients with hypertension and that exercise training would reduce MSNA and blood pressure (BP) in hypertensive patients. Twenty never-treated hypertensive patients were randomly divided into 2 groups: exercise-trained (nϭ11; age: 46Ϯ2 years) and untrained (nϭ9; age: 42Ϯ2 years) patients. An age-matched normotensive exercise-trained group (nϭ12; age: 42Ϯ2 years) was also studied. Key Words: hypertension Ⅲ baroreflex sensitivity Ⅲ sympathetic nerve activity Ⅲ exercise Ⅲ blood pressure T here is accumulated evidence that arterial baroreflex plays an important role in the regulation of the cardiovascular system. During spontaneous variation of blood pressure (BP), stimulation or deactivation of the arterial baroreceptors located in the carotid sinus and aortic arch causes reflex bradycardia and tachycardia, respectively. At the vascular level, stimulation of the arterial baroreceptors results in sympathetic inhibition and, in consequence, reflex vasodilation. In contrast, the deactivation of the arterial baroreceptors elicits sympathetic-mediated vasoconstriction. 1 All of these responses work in concert to maintain the BP levels in the reference range. 1It has been described that arterial baroreflex sensitivity can be profoundly altered in some cardiovascular diseases. 2,3 In hypertension, some investigators, 4 -6 but not all, 7-9 observed that baroreflex control of heart rate (HR) and sympathetic nerve activity is significantly reduced. This autonomic dysfunction seems to correlate with an increase in sympathetic outflow and in BP levels. 10 On the other hand, previous studies have demonstrated that regular exercise causes significant changes in baroreflex control of HR in experimental hypertension. Exercise training improves baroreflex control of HR during the increase and decrease of BP in spontaneously hypertensive rats. 11,12 Furthermore, these studies indicate that the improvement in baroreflex sensitivity is, in part, mediated by the enhancement of the aortic depressor nerve sensitivity. In humans with hypertension, little information exists regarding the effects of exercise training on the baroreflex sensitivity. One of the few studies showed that exercise training caused a modest improvement in baroreflex bradycardia. 13 Thus, the effects of regular exercise on the baroreflex control of sympathetic nerve activity in humans with hypertension are unknown.It has been consistently shown that exercise training is a powerful nonpharmacological strategy to reduce BP levels in humans with hypertension. 14 -16 However, the mechanisms involved in the BP reduction after exercise training are still a matter of discussion. In the present study, we investigated the

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The short-term reduction in blood pressure after exercise in elderly hypertensive patients is associated with a decrease in stroke volume and left ventricular end-diastolic volume. The 22-h postexercise reduction in blood pressure demonstrates the clinical relevance of low-intensity exercise in elderly hypertensive patients.

Home-based IMT represents an important strategy to improve cardiac and peripheral autonomic controls, functional capacity, and quality of life in patients with CHF.