EFFECTS OF DIFFERENT TRAINING INTENSITIES ON THE CARDIOPULMONARY BAROREFLEX CONTROL OF FOREARM VASCULAR-RESISTANCE IN HYPERTENSIVE SUBJECTS

We recently reported that ambulatory blood pressure decreased during t he awake period after training at low intensity but not after training at moderate intensity in subjects with mild to moderate hypertension. The reasons for the failure of moderate-intensity training to reduce blood pressure are not clear. In the present article, we report the ef fects of different training intensities on cardiopulmonary baroreflex control of forearm Vascular resistance, left ventricular function, vas cular reactivity, and resistive vessel structure. After moderate-inten sity training, the cardiopulmonary baroreflex control of forearm vascu lar resistance was significantly attenuated, left ventricular performa nce was enhanced, and vascular reactivity and resistive vessel wall th ickness in the calf were reduced compared with values after the contro l sedentary period. No significant changes in these indexes were found after low-intensity training compared with sedentary values. These re sults indicate that attenuation of the cardiopulmonary baroreflex cont rol of skeletal muscle vascular resistance after training at moderate intensity may contribute to the lack of antihypertensive effects, as s een from unchanged ambulatory blood pressure levels during the awake p eriod, after training at this intensity. A decreased vascular smooth m uscle response to sympathetic nervous stimulation appears to be partly involved in the alteration in the baroreflex control of forearm vascu lar resistance after moderate-intensity training. Although these findi ngs should be confirmed in a greater number of subjects, the present r esults point to a key mechanism that might explain why moderate endura nce exercise training fails to lower arterial blood pressure in hypert ensive subjects.