It is well documented that both physical fitness and physical activity (PA) are associated with reduction of the mortality from all causes and from cardiovascular diseases. In addition, it has been shown that not only in the young or middle-aged but also in the older people the increase in the level of PA coincides with the reduced morbidity and mortality from a coronary heart disease as well as with the reduced rate of deaths from all causes. It is not clear, however, which of the two - physical fitness or physical activity - reduces the risk of a premature death to a greater extent. Also, no conclusion has been reached about how intensive physical exercising should be to substantially decrease the mortality rate. Some authors suggested that it is moderate to moderately vigorous activity that suffices to beneficially affect longevity. Moreover, moderate activity is safer, especially for the previously sedentary people. However, in case of the healthy subjects adapted to the high intensity training, the beneficial effect of vigorous exercising should not be neglected.