Exercise Induces Unequal Changes in Heart Nerve Structures

A recent study has shown that moderate aerobic exercise produces significant asymmetrical alterations in the nerve clusters controlling the heart, with the right and left stellate ganglia responding in markedly different ways. This discovery challenges previous assumptions about uniform nervous system adaptation to physical activity.

Conducted by the University of Bristol and published in Autonomic Neuroscience, the research examined how 10 weeks of treadmill exercise affected the stellate ganglia—paired sympathetic nerve bundles located near the neck and upper chest that modulate heart rate and blood pressure.

Distinct Neural Adaptations on Each Side

Using advanced 3D imaging and stereological methods on rats, researchers found that the right stellate ganglion developed approximately four times more neurons compared to the left after the exercise regimen. In contrast, neurons on the left side increased in size by about 1.8 times, while those on the right slightly decreased in size. The overall volume of these nerve clusters diminished following training.

These findings reveal a previously unrecognized left-right asymmetry in how the autonomic nervous system remodels in response to aerobic exercise, suggesting that the heart’s regulatory “dimmer switch” operates differently on each side.

Implications for Cardiac Therapies

Lead author Augusto Coppi, Senior Lecturer in Veterinary Anatomy at the University of Bristol, emphasized that these side-specific changes could explain why some cardiac treatments targeting the stellate ganglia, such as nerve blocks or denervation, show variable effectiveness. These interventions are applied in conditions like arrhythmias, refractory angina, and Takotsubo cardiomyopathy, also known as “broken-heart” syndrome.

Coppi noted that while the current results derive from animal models, further research is planned to assess whether similar asymmetrical adaptations occur in humans and larger animals. Future studies will also explore how these structural changes influence heart function during rest and exercise, potentially guiding more precise therapeutic approaches.

“Understanding the distinct remodeling on each side of the autonomic nervous system could enable personalized treatments for heart rhythm disorders and chest pain,” Coppi stated. “Our next step involves correlating these anatomical changes with functional outcomes in clinical settings.”

Study Details and Future Directions

The research, titled “Asymmetric neuroplasticity in stellate ganglia: Unveiling side-specific adaptations to aerobic exercise,” was authored by Fernando Vagner Lobo Ladd, Aliny Antunes Barbosa, Renato Albuquerque de Oliveira Cavalcanti, Mariana Pereira de Melo, Andrzej Loesch, and A. Augusto Coppi. It appeared in the December 2025 issue of Autonomic Neuroscience: Basic and Clinical.

As the study progresses, noninvasive techniques will be employed to verify these findings in humans, aiming to refine understanding of how exercise-induced neuroplasticity impacts cardiovascular health and treatment efficacy.