Frequent exercise doesn’t just strengthen the heart – it also changes the nerves that control it, according to new research which could guide more targeted and effective care for common heart problems. The study, led by the University of Bristol (UK), shows for the first time that moderate aerobic training reshapes nerves that drive the heart, and affects them on each side of the heart differently. The research is published in the journal Autonomic Neuroscience. Findings highlighting this marked left-right split could ultimately be used to treat more effectively a range of conditions, including irregular heartbeats,chest pain, angina pain, and ‘broken-heart’ syndrome. 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. “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.” The research used advanced 3D quantitative imaging analysis methods called stereology. Findings showed that trained rats over a 10-week period had around four times more nerves – calledneurons– in the cardiovascular cluster on the right-hand side of the body than the left compared to untrained rats. Conversely, the neurons on the left nearly doubled in size while those on the right slightly shrank. 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.” Ref:Asymmetric neuroplasticity in stellate ganglia: Unveiling side-specific adaptations to aerobic exercise; Ladd, Fernando Vagner Lobo et al. Autonomic Neuroscience: Basic and Clinical, Volume 0, Issue 0, 103338. Doi: 10.1016/j.autneu.2025.103338