Exercise combined with lower body negative pressure resulted in reflex heart rate gains (-0.83 beats/min/mmHg) significantly greater than the sum of gains during exercise and LBNP alone (P<0.05).
p-value: p=<0.05
Numerous studies have reported that, at rest, maximal carotid baroreflex gain is modulated by cardiopulmonary baroreceptors. The purpose of this study was to measure the maximal gain for carotid baroreflex control of heart rate (HR) and blood pressure mean arterial pressure (MAP) during dynamic exercise alone and when exercise was accompanied by two levels of cardiopulmonary baroreceptor unloading. Lower body negative pressure (LBNP) produced similar reductions in central venous pressure (CVP) at rest and during exercise. Baroreflex gain for HR at rest was not affected by low-level LBNP but was significantly increased by high-level LBNP [-0.31 +/- 0.05 to -0.57 +/- 0.23 beats.min-1.mmHg-1 carotid sinus pressure (CSP), no LBNP vs. high-level LBNP, P 0.05). Together these data indicate 1) a tonic inhibitory interaction between cardiopulmonary baroreceptors and carotid baroreflex control of HR during exercise, and 2) a nonlinear relationship between deactivation of cardiopulmonary baroreceptors and changes in carotid baroreflex gain. This interaction may improve overall cardiovascular regulation when central blood volume and/or CVP is reduced, as has been reported during prolonged exercise in the heat.
Potts et al. (Sat,) reported a other. Lower body negative pressure (LBNP) and dynamic exercise vs. Rest and exercise alone was evaluated on Maximal gain for carotid baroreflex control of heart rate (p=<0.05). Exercise combined with lower body negative pressure resulted in reflex heart rate gains (-0.83 beats/min/mmHg) significantly greater than the sum of gains during exercise and LBNP alone (P<0.05).
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