ABSTRACT
A high aerobic capacity is a prerequisite for success in all endurance-based sports, and many different factors contribute to the body’s ability to derive energy from oxidative metabolism. Although maximum cardiac output is often considered to be the limiting factor to oxygen transport, this is true only in the absence of another limitation. For different individuals and in different situations, any of the steps in the chain of oxygen transport and use, from pulmonary function to mitochondrial enzyme activity, may determine this limit. This includes the transport of oxygen in the circulation, which in turn depends on the blood haemoglobin concentration and the total red blood cell mass. For this reason, athletes are often concerned to know their circulating haemoglobin concentration, as this is the most widely understood measure of adequacy or otherwise of an individual’s iron status and is also the marker that is most closely related to exercise performance. Although it can be argued that other markers may be of more diagnostic use, it is generally accepted that some form of haematological assessment is an important part of any routine screening of athletes being carried out as part of a sports science or sports medicine athlete support programme.
