Aitor Hernandez Orbea Ciclocross

The cardiovascular system’s functions, amongst others, are to deliver oxygen and nutrients to all tissues of the body and to remove waste products, to control heat flux within the body, and to circulate hormones from the sites of their production to the sites of their action. There is strong experimental evidence to support the idea that limitations to oxygen delivery are imposed by the cardiovascular system and that the limitation may lie at any one or more of several stages.


The key element seems to be the maximum cardiac output that can be achieved, as this is related to both Vo2max and endurance performance. The size of the heart, and more specifically of the left ventricle, is also important. This determines the stroke volume – the amount of blood ejected with each beat of the heart – and the cardiac output (the product of heart rate and stroke volume) is closely correlated with both Vo2max and endurance performance. In elite endurance athletes the cardiac output can exceed 40 l/min, compared with the maximum of about 20 l/min that the sedentary individual can achieve. As maximum heart rate does not change much, this difference is accounted for almost entirely by the greater stroke volume of the endurance athlete.


A high blood volume will also benefit the endurance athlete by helping to maintain central venous pressure, thus maintaining stroke volume.