July 29, 2008 Just like any other muscle, the structure of the heart can be changed through exercise. However, this adaptation process takes longer than it takes the muscle to revert to its original conditions. Researchers from the Universidad Politécnica de Madrid (UPM) have studied this process in well trained hearts during their investigations to identify pathologies.
Certainly everyone has at some point realized that the efforts at the gym result in increased muscle tone, even if this is not easy to maintain. The same applies to the heart; after enduring intense physical exercise some of its characteristics change. Thanks to modern imaging technology, in particular echocardiography, the study of such characteristics has greatly improved.
In sports medicine, it is very important to know how the heart adapts and regresses to its original state in athletes who train intensively. The information of the regression of the heart to a normal status when the training stimulus is removed is used by sports cardiologists to delimit the physiologic adaptation of the pathology.
In general, all the studies carried out with echocardiography for sports people with high levels of heart adaptation (rowers, cyclists, long distance runners…) have proven that the effects of heart training are increases in the size of the cavities (mainly the left ventricle) and thickness of the myocardium. Nonetheless, the regression of echocardiographic measurements caused by the decrease in training intensity has so far shown contradictory results.
Correctly interpreting the echocardiographic images and understanding the regression of the heart to its initial status is crucial, as there are heart diseases that resemble the natural adaptation caused by training. For this reason, since the initial study with sports athletes, there have been numerous others with the direct or indirect objective of determining the differences between a healthy heart and an unhealthy one.
Researchers from the Laboratorio de Fisiología del Esfuerzo of the Facultad de Ciencias de la Actividad Física y del Deporte of the Universidad Politécnica de Madrid, in collaboration with British and Italian scientists, have studied the reasons for the inconclusive results, that up to now have resulted from the study of the adaptation and regression caused by training.
The main conclusion is that regression is a relevant process when attempting to distinguish the physiological phenomenon that the training represents from the effects of heart diseases. In the case of a healthy trained heart, it reverts to it's original measurements once the stimulus disappears, as opposed to the case of an ill heart (“Hypertrophy” or “Dilatation of the heart”) that might exhibit similar alterations, but maintains or aggravates these produced changes. When an exaggerated hypertrophy is detected in an examination by sports cardiology services, the treatment to be followed is precisely to change the training regime.
In order to understand the technical limitations of echocardiography in determining the small variations that could be produced when the cavities size and the myocardium thickness are measured, it is convenient to look at some pictures.
Figure one shows an echocardiographic image, to the left in one dimension and to the right in two dimensions. The "area” to be measured is registered in two dimensions, but the measurements are taken in one dimension only. In figure two, a freehand representation of the image shown in figure one is represented. The average variation of thickness demonstrated by the different studies that were analysed range from 1 to 5 mm, which gives an idea of the rigour necessary to evaluate echocardiographies.
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