Objective - formation on the basis of erythrocyte characteristics of objective, adequate and informative criteria to be used for estimating body functional state and physical work capacity of athletes in the dynamics of training process. Меthods. Аnalysis and generalization of data of scientific and methodical literature and those of personal studies.
Results. Dynamic study of erythrocyte mean diameter in elite swimmers has been performed. It has been revealed that in rest this index was significantly higherin swimmers as compared to nonathletes. One of the reasons of increased erythrocyte diameter in swimmers is the activation of reticulocytosis. Erythrocyte diameter in swimmers in rest has been demonstrated to correlate with the result in 1500 m swimming; immature forms of reticulocytes participating in urgent replenishment of oxygen deficit have been revealed in athletes’ blood after the load. It is assumed that increased erythrocyte diameter and ratio of its surface area to volume contributes to better perfusion and oxygen delivery to tissues.
Conclusion. Change of erythrocyte size is rather reliable marker of body functional state and may be used as the objective criteria of work capacity at the stages of medico-biological control of athletes including the operative control.