Recreational sports activity has been recognized as a key factor in health preservation and extending lifespan. Recent research show concern about the potentially negative consequences of sports activities that occur due to a large accumulated number of exercise hours and high-intensity training. The occurrence of change is described by the so-called U-curve, that shows the existence of hours limit and training intensity above which the incidence of cardiovascular diseases such as atrial fibrillation, ventricular arrhythmia, coronary heart disease, and sudden cardiac death, is increased. It has also been found that intense sporting activity can lead to a decrease in expected lifespan extension. Considering the relatively large number of required accumulated exercise hours, such phenomena are characteristic of recreational athletes of middle and old age. The cause of the above mentioned phenomena could be pathological structural and electrical changes of the heart caused by intense sports activities, and the key part is the right part of the heart that shows a limited ability of adjustment to prolonged physical activity. Acute changes, which include a marked decrease in the systolic and diastolic function of the right ventricle, may, due to multi-year training, lead to the appearance of the irreversible pathological substrate. In practice, pathological changes are often misdiagnosed as a physiological adaptation called an athletic heart. Cardiologic and sports associations propose guidelines for recreational sports activities for the general population with the aim of optimizing activities, which means achieving maximum positive health effects while minimizing negative consequences. For people with previous episodes of cardiovascular diseases, an estimation of existing residual physical activity capacity and an individually adjusted training regime under the control of medical professionals and kinesiologists are proposed to prevent re-incidents and physically rehabilitate patients.