Most people know that regular exercise helps lower blood pressure, improve fitness, and reduce the risk of heart disease.
Scientists have now discovered another possible reason why exercise is so good for the heart. It may actually change the nerves that control how the heart works.
The study was led by researchers at the University of Bristol in the United Kingdom and published in the journal Autonomic Neuroscience.
The findings suggest that moderate aerobic exercise reshapes the heart’s nerve network in a surprising way that differs between the left and right sides of the body.
The heart does not work alone. It is constantly controlled by the autonomic nervous system, which automatically adjusts heart rate and pumping strength without us having to think about it. This system helps the body respond to exercise, stress, fear, and rest.
Scientists focused on small groups of nerves called stellate ganglia.
These nerve clusters sit in the lower neck and upper chest and send signals that tell the heart to beat faster or more forcefully when needed. Doctors sometimes target these nerves when treating dangerous heart rhythm disorders or severe chest pain.
The research team worked with scientists from University College London, the University of São Paulo, and the Federal University of São Paulo. They used advanced three-dimensional imaging to study how 10 weeks of regular aerobic exercise changed these nerves in rats.
The results were unexpected. Exercise caused many more nerve cells to appear on the right side of the cardiovascular nerve cluster, while nerve cells on the left side became much larger. This showed that exercise remodels the heart’s control system differently on each side of the body.
The researchers believe these differences could help explain why some medical procedures aimed at calming overactive heart nerves appear to work better on one side than the other. Understanding these patterns may eventually allow doctors to choose more precise treatments for each patient.
Conditions such as irregular heart rhythms, angina, and stress-induced cardiomyopathy, sometimes called broken-heart syndrome, may all involve overactive nerve signals reaching the heart. If future studies confirm the findings in people, treatments such as nerve blocks or denervation procedures could become more targeted and potentially more effective.
The study was performed in rats, so the findings cannot yet be directly applied to humans. Many promising animal studies do not always produce the same results in clinical practice. More research is needed before doctors can change current treatments.
The researchers now plan to study whether the same left-right differences occur in larger animals and in people. They also want to understand how these nerve changes affect heart function during exercise and while resting.
Review and analysis: This research provides an entirely new explanation for some of the heart-protective effects of regular exercise.
Its greatest strength is the discovery of a previously unknown difference between the left and right heart-control nerves. However, because the study was conducted only in rats, it should be viewed as an important early finding rather than evidence ready for clinical use.
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Source: University of Bristol.
