Exercise rewires the heart’s nerve network, study finds

After 10 weeks of moderate aerobic exercise, rats showed major changes in the nerve hubs that help drive the heart, with the right side responding far more strongly than the left. Researchers at the University of Bristol, working with University College London, the University of São Paulo and the Federal University of São Paulo, published the findings Sept. 24, 2025 in Autonomic Neuroscience and used stereology, a 3D quantitative imaging method, to track the changes.

The paired stellate ganglia, small nerve hubs in the lower neck and upper chest that send “go faster” signals to the heart, did not respond symmetrically. After 10 weeks, trained rats had about four times as many neurons in the cardiovascular cluster on the right side as untrained rats, while neurons on the left nearly doubled in size and those on the right slightly shrank.

Dr. Augusto Coppi said the pattern revealed a previously hidden layer in the body’s autopilot system and could one day help doctors target therapies more precisely and effectively. The conditions include irregular heartbeats, angina and stress-induced broken-heart syndrome. The work was done in rats, not patients.

A 2012 study in people with chronic cardiomyopathy found neuronal hypertrophy in the left stellate ganglion. Another rat study found chronic forced running increased tyrosine hydroxylase and dopamine beta-hydroxylase levels in stellate ganglia.

Adults should get at least 150 minutes of moderate-intensity physical activity each week plus 2 days of muscle-strengthening activity, according to the Centers for Disease Control and Prevention. The World Health Organization recommends that adults ages 18 to 64 do at least 150 minutes of moderate activity or 75 minutes of vigorous activity weekly, with added benefit up to 300 minutes of moderate exercise.