Exercise found to have the ability to "reprogram" the heart

Regular aerobic exercise changes not only how the heart works but also the structure of the nerve ganglia involved in its regulation. Moreover, the changes on the right and left sides turned out to be different. This result was obtained by researchers from the University of Bristol and other scientific centers in experiments on rats. The study was published in the journal Autonomic Neuroscience.

The scientists studied the stellate ganglia — paired clusters of sympathetic nervous system cells located in the lower neck and upper chest. Their signals help the heart adapt to exertion, including by accelerating contractions.

The animals performed moderate aerobic exercise on a treadmill for ten weeks. The researchers then used three-dimensional analysis and stereology to assess the number and size of neurons as well as the volume of the ganglia, comparing trained rats with untrained ones.

After training, the right ganglion contained approximately four times more neurons than the left. No such asymmetry was found in untrained animals. This is a comparison between the two sides of the body, not evidence of a fourfold increase in the total number of cells following exercise.

Neuron sizes also changed unevenly: on the left, cells became nearly twice as large, while on the right they slightly decreased. Thus, the nervous system adapted to exercise asymmetrically.

The authors suggest that these differences may prove important for understanding the neural regulation of the heart. In certain