The brain is the command center for the body, especially during times of stress such as exercise. Mechanisms throughout your body are set up to provide feedback to the brain so that adjustments can be made through the autonomic nervous systems. Baroreceptors are one of these biofeedback outlets. They respond and adapt to exercise training.
Baroreceptors are feedback mechanisms in the aortic arch, carotid sinus, heart and pulmonary vessels. The job of the baroreceptor is to report to the brain the amount of stretch inside the artery. For health and cardiovascular safety, the body must maintain the pressure in a safe range. During pressure changes, the baroreceptors fire, which signals to the medulla that either pressure is too low or too high around the heart.
Baroreceptors establish a set point for blood pressure. When the blood pressure increases above or decreases below the set point, the baroreceptor contacts the brain, which signals a change. An increase above the set point causes the brain to reduce sympathetic nervous system stimulation to decrease the blood pressure. A decrease in blood pressure causes the brain to stimulate the sympathetic nervous system to bring the blood pressure back up, such as what happens when you stand suddenly.
At the onset of exercise, the baroreceptor set point increases, which influences the blood pressure and heart rate. A change in the set point is important because it influences the sympathetic nervous system innervation. It also helps promote vasodilation and vasoconstriction around the body. With regular exercise, the baroreceptor reflex becomes faster, which is critical for athletes.
Regular exercise training produces changes inside your body, including changes to the baroreceptor reflex. With regular exercise, the amount of blood that circulates throughout your body increases. This also includes the capacity of your heart to pump more blood. Both of these mechanisms might initiate a response by the baroreceptor reflex. Therefore, there must also be an adaptation to the baroreceptor or it could fire to the brain, even at times of rest, because a larger cardiac output and a higher blood volume will both initiate stretch in the artery.
- "Exercise Physiology"; George A. Brooks, Thomas D. Fahey, Kenneth M. Baldwin; 2005
- CV Physiology.com: Arterial Baroreceptors; April 2007
- "ACSM's Advanced Exercise Physiology"; 2006