Behaviour of haematological parameters in athletes performing marathons and ultramarathons in altitude ('skyrunners').

We observed athletes performing marathons and ultramarathons in altitude over several years to study the behaviour of haematological parameters in order to screen eventual paraphysiological or pathological conditions (sports anaemia). We collected samples from 124 athletes participating in seven races; 23 athletes were recruited in different races: 16 for four times, four for three times, and three for two times. The pre- and post-race values of erythrocytes, haemoglobin and packed cell volume did not show statistically significant differences in the studied athletes. The erythrocytes' indices (MCV, MCH, MCHC) and red cell distribution width (RDW) also were not significantly modified by the strenuous effort. The leukocytes were significantly increased because of immunological involvement during the endurance performance. Platelets and relative indices were not significantly modified. The stability of packed cell volume and haemoglobin in athletes performing training and races in altitude is strong evidence for the use of these parameters as an index of general health status and for illustrating possible abnormal increase because of exogenous stimulation of bone marrow. The preanalytical and analytical accuracy is crucial to assure clinical validity of the collected data: we strictly observed international recommendations in this field.