Researchers at New Zealand’s University of Auckland have discovered that the vagus nerve, known for its role in ‘rest and digestion’, plays an important role in exercise, helping the heart pump blood, which carries oxygen to the whole body.
Currently, exercise science maintains that the ‘fight or flight’ (sympathetic) nervous system is active during exercise, helping the heart beat faster, and that ‘rest and digest’ ( parasympathetic) nervous system ‘ is reduced or inactive. However, associate professor of physiology at the University of Auckland Rohit Ramchandra points out that this current knowledge is based on indirect estimates and many assumptions that his new study shows to be wrong.
“Our study found that the activity of these ‘rest and digest’ vagal nerves actually increased during exercise. Our group used ‘tour de force’ electrical recording techniques to directly monitor vagal nerve activity during exercise in sheep and found that the activity of the vagal nerves that go to the heart increases during exercise,” said Ramchandra.
“For the heart to maintain a high level of pumping, more blood flow is needed during exercise to increase the additional work it does: our data show that the increased activity of vagal that’s all,” he added.
During exercise, the amount of blood pumped by the heart per minute increases four to five times. This causes the heart to beat faster and contract harder. The heart’s ability to pump blood is modulated by nerves traveling from the brain, which is called ‘autonomic’ because it works automatically and does not require conscious thought.
These nerves include the ‘fight or flight’ or sympathetic nerves and the ‘rest and digest’ vagal nerves, called parasympathetic nerves. The vagus nerve connects the brain to the heart and other internal organs, including the gut, and regulates the ‘rest and digest’ responses of the parasympathetic nervous system.
New research has found that the parasympathetic and sympathetic nervous systems work together during exercise to help the heart pump harder and faster. The researchers also examined the role of mediators released by the cardiac vagal nerve.
“The cardiac vagus nerve releases many mediators, and previous research has focused on one neurotransmitter, acetylcholine, which has no effect on our ability to exercise,” said Ramchandra.
“Our study focused on a different mediator, vasoactive intestinal peptide (VIP), and showed that the vagus nerve releases this peptide during exercise, which helps the coronary vessels to dilate allowing more blood that pumps the heart. “, Add.
The test was conducted on sheep, due to their similarity to humans in many important aspects, including cardiac anatomy and physiology. They are also well established as an animal model to help find ways to combat heart disease that translate to humans. These basic findings may have applications in diseases, including heart failure, in which people cannot tolerate exercise.
“This inability to perform simple, strenuous tasks means that the quality of life is severely compromised in these patients. One possible reason for reduced exercise tolerance is that the diseased heart does not receive enough blood.
The follow-up study will try to see if this important function of the cardiac vagal nerves can be used to improve exercise tolerance in heart failure. There is a lot of interest in trying to “hack” or improve vagal tone as a way to reduce anxiety; Investigating this is outside the scope of the present study.
Ramchandra points out that the vagus nerve mediates the slowing of the heart rate and if there is high vagal activity, then the heart rate should slow down. “I’m not sure if it’s the same as relaxation, but we can say that regular exercise improves vagal activity and has beneficial effects,” concluded the researcher who published his study in ‘Circulation’.
