How does regular physical exercise protect against sudden cardiac death?

A group of researchers from the departments of Physical Therapy, Medicine and Electronic Engineering of Valencia University and from the innovations group ITACA have just published research into physical exercise as a protector against sudden cardiac death. The study has been published in the ‘PlosOne’ journal.

The team is comprised by Luis Such-Miquel, Laia Brines, Antonio M. Alberola, Mauel Zarzoso, Francisco J. Chorro, Juan Guerrero, Germán Parra, Nathalia Gallego, Carlos Soler and Irene Del Canto. Specialists of the Incliva and the Polytechnic University of Valencia have also participated.

Moderate, aerobic physical exercise protects against sudden cardiac death, which in a majority of cases is caused by the deadliest type of arrhythmia: ventricular fibrillation. In fact, aerobic physical exercise has been suggested as a non-pharmacological treatment against arrhythmias.

However, the exact underlying cardio-vascular protection mechanisms are not fully understood. This research tries to clarify that the application of an aerobic physical exercise protocol in sedentary animals, such as lab rabbits, can have a beneficial effect on the electrical properties of the heart which are related to ventricular fibrillation. Furthermore, they attempted to learn whether neurons that are in the heart, cholinergic neurons, play a role in the potential modifications caused by moderate training.

The researched properties have been the intrinsic electrophysiological heterogeneity and modifications to electrical stability. This study has been conducted on an isolated rabbit heart, which has been the subject of the study of the effects of prolonged physical exercise on the aforementioned properties, as well as the consequences on these properties, which includes blocking the action of these neurons on the cardiac cells.

After conducting the experiments and analysing the results, they observed that, in the isolated and perfused rabbit heart, the training via a protocol of physical exercise produced increased ventricular refractoriness, a decrease of ventricular electrophysiological heterogeneity, and an increase of electrical stability. These properties have been modified in a beneficial way by the applied physical exercise protocol. This way, they have contributed to clarifying the basic mechanisms through which regular physical exercise has a protective effect against sudden cardiac death, as well as providing information on the participation of cholinergic cardiac neurons on the aforementioned modifications.

The researchers conclude in their study that the result obtained in the study suggest the need to continuing with this line of research in order to clarify the underlying mechanisms of the observed modifications.