You’ve probably heard that regular aerobic exercise is good for your heart. But did you know it might also reshape the tiny nerve clusters that help run it?
Researchers from the University of Bristol, working with teams in the UK and Brazil, have discovered that moderate-intensity aerobic exercise can remodel the stellate ganglia, a pair of nerve hubs in your neck that act like the heart’s “dimmer switch.” These ganglia help regulate heart rate by sending sympathetic signals, and now we know they respond to exercise in surprisingly asymmetric ways.
This is the first time researchers have demonstrated that moderate aerobic training reshapes nerves that control the heart, and affects them differently on each side of the heart.
Study lead author Dr Augusto Coppi, Senior Lecturer in Veterinary Anatomy at the University of Bristol, said: “The discovery points to a previously hidden left–right pattern in the body’s ‘autopilot’ system that helps run the heart.”
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“These nerve clusters act like the heart’s dimmer switch, and we’ve shown that regular, moderate exercise remodels that switch in a side-specific way. This could help explain why some treatments work better on one side than the other and, in the future, help doctors target therapies more precisely and effectively.”
Using advanced 3D imaging and stereological analysis, the team studied mice after 10 weeks of treadmill training. They compared four groups: left-side ganglia in untrained rats, Left-side ganglia in trained rats, Right-side ganglia in untrained rats, and Right-Side ganglia in trained rats.
The results were striking:
- The right stellate ganglion showed a fourfold increase in neuron count compared to the left.
- Right-side neurons shrank (atrophy), while left-side neurons grew (hypertrophy).
- Overall, ganglion volume dropped by 1.04-fold on the left and 1.4-fold on the right.
- This left–right difference wasn’t seen in untrained animals, suggesting that exercise triggers a side-specific remodeling of the heart’s nerve control system.
And here’s the kicker: the ganglia sit near the Virgo cluster’s equivalent in your body, a hot zone of nerve activity. When overactive, they’re linked to arrhythmias, stress-induced “broken-heart” syndrome, and certain types of chest pain. Treatments like nerve blocks or denervation often target these ganglia, but until now, it was unknown whether one side might respond differently from the other.
Dr Coppi explained: “Irregular heart rhythms, known as arrhythmias, stress-induced broken‑heart syndrome, and certain types of chest pain are often treated by dialling down overactive stellate ganglia, the paired small nerve hubs in the lower neck/upper chest area that send ‘go faster’ signals to the heart.”
“By mapping how exercise changes these ganglia on each side, the study offers clues that could one day fine‑tune procedures like nerve blocks or denervation to the side most likely to help. The findings are early-stage and in rats, so clinical studies would need to follow.”
The team is now planning follow-up studies to investigate how these structural changes impact heart function and whether similar patterns emerge in larger animals and humans. If so, it could pave the way for more personalized treatments for heart rhythm disorders and angina.
Dr Coppi added, “Understanding these left-right differences could help us personalise treatments for heart rhythm disorders and angina. Our next step is to test how these structural changes map onto function and whether similar patterns appear in larger animals and humans.”
Journal Reference:
- Fernando Vagner Lobo Ladd et al. Asymmetric neuroplasticity in stellate ganglia: unveiling side-specific adaptations to aerobic exercise. Autonomic Neuroscience. DOI: 10.1016/j.autneu.2025.103338