A July 2026 study from the University of Bristol, published in Autonomic Neuroscience, reports that 10 weeks of aerobic training in rats produces asymmetric changes in the stellate ganglia, paired nerve clusters in the lower neck and upper chest that send “go faster” signals to the heart. Lead author Dr. Augusto Coppi, Senior Lecturer in Veterinary Anatomy at the University of Bristol, described the discovery as revealing a previously hidden left-right pattern in the body’s “autopilot” system for the heart, with possible long-term implications for treating arrhythmias, angina, and stress-induced “broken-heart” syndrome.
What did the researchers actually find?
The team trained rats over a 10-week regimen and then used advanced three-dimensional imaging techniques called stereology to count and measure neurons in the stellate ganglia. Trained animals had roughly four times as many neurons in the right cardiovascular nerve cluster relative to the left, compared with untrained controls. At the same time, neurons on the left side nearly doubled in size, while those on the right became slightly smaller. Dr. Coppi likened the nerve clusters to a dimmer switch for the heart, saying that exercise remodels that switch in a side-specific way.
Why does the left-right pattern matter?
The stellate ganglia sit within the sympathetic chain, the branch of the autonomic nervous system that regulates heart rate and contraction force. Because the two sides respond differently to the same training stimulus, the researchers describe the result as a previously unrecognized form of left-right neuroplasticity in autonomic control of the heart. Understanding which side does what could matter for procedures that already target these nerves.
Potential clinical implications
Doctors currently treat some arrhythmias, angina, and stress-induced cardiomyopathy by targeting the stellate ganglia with nerve blocks or denervation, procedures that intentionally interrupt overactive sympathetic signaling. The study suggests that the left-right differences observed after exercise could help clinicians decide which side to treat for the best effect. Dr. Coppi noted that this could one day allow more personalized therapies, though clinical trials would be needed before any change in practice.
What are the limits of the study?
The work was conducted in rats and is considered early-stage, with the authors cautioning that clinical application requires further investigation. Planned next steps include testing how the structural changes affect heart performance during exercise and at rest, using non-invasive markers in humans. The team also aims to determine whether the same left-right pattern appears in other animal models and ultimately in human patients. Funding and collaborations involved University College London, the University of São Paulo, and the Federal University of São Paulo in Brazil.
How does this fit with what we already know about exercise and the heart?
Aerobic exercise has long been associated with improved cardiovascular health, including better endothelial function in people with conditions such as Type 2 diabetes after resistance-based interval training. The Bristol study extends that picture by suggesting that training does not only strengthen the heart muscle but also reorganizes the neural circuitry that drives it.
FAQ
What are the stellate ganglia?
The stellate ganglia are paired nerve clusters in the lower neck and upper chest that belong to the sympathetic nervous system. They help regulate heart rate and the force of heart contractions by sending excitatory signals to cardiac tissue.
What kind of exercise did the rats do?
The study used an aerobic training protocol lasting 10 weeks. The exact treadmill or swimming regimen is described in the paper itself, published in Autonomic Neuroscience.
Could this change how heart rhythm problems are treated?
Potentially. The researchers suggest that the left-right differences could help fine-tune procedures such as nerve blocks or denervation, but clinical trials in humans are needed before any treatment guidelines change, according to Dr. Coppi.
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This article summarizes reporting from naturalnews.com.
