Echinocytosis in athletes with exercise-induced hypoxemia

Abnormal hemorheology has been proposed previously as a possible genesis of exercise-induced hypoxemia (EIH) in humans. This study, in support of the hemorheological hypothesis, aims at determining if red blood cell shape changes might be related to EIH. Three groups of subjects: one without EIH (n=5); one developing mild-EIH (n=7); and, one with moderate EIH (n=5). Each group performed a progressive and maximal exercise test on cycle-ergometer. We evaluated the percent of stomatocytes, echinocytes and schizocytes in blood smears prepared from phlebotomy samples taken at rest and at maximal exercise. The percent of schizocytes or stomatocytes was not different between the three EIH groups at rest; and, exercise produced no change from the resting values of those cell types. The percent of echinocytes was not different between the three EIH groups at rest, however, exercise significantly increased the percent of echinocytes from the resting value of both the mild- and moderate-EIH groups, while the non-EIH group remained unchanged. We suggested that the rigidity of echinocytes could have contributed to the genesis of EIH.