DOES SUBMAXIMAL EXERCISE AFFECT ERYTHROCYTE OSMOTIC FRAGILITY AND SERUM MDA LEVELS OF DISTANCE RUNNERS?

Abstract

Optimal erythrocyte function is necessary to achieve athletic performance. Erythrocyte susceptibility to haemolysis is known to be increased in parallel with osmotic and oxidative stress, following a single episode of submaximal exercise. Haemodilution is not a cause of sports anemia, which may follow intravascular haemolysis caused by the recurrent mechanical trauma of erythrocytes, to which also contribute oxidative and osmotic stress, and lactate diffusion into these cells. The aim of this study is to examine haematological parameters, namely haemoglobin (Hb), haematocrit (Hct), red blood cell (Rbc) count, mean cell volume (MCV), mean corpuscular haemoglobin (MCH) mean corpuscular haemoglobin concentration (MCHC), erythrocyte osmotic fragility (EOF), and malondialdehyde (MDA) levels as a determinant of lipid peroxidation in middle-distance athletes, before, and 1, 4 and 24 hours following an episode of submaximal exercise, to assess the time course of change of these parameters in reaching their pre-exercise levels. A total of 14 medium level trained athletes were made to run 5000 m in 16 min. Fasting blood samples were collected into both plain and K3-EDTA tubes, and analyzed in two hours in a haemocounter. EOF was stabilized by the method described in the Merck Manual, and MDA was determined by the Yoshika and Kawada method. Statistical analysis was done using SPSS v8.0, with the Friedman test, accepting p<0.05 as significance level. All parameters, except MCV and Hct levels, were high in the first hour, and after 24 hours were near to, or below their pre-exercise levels. Except for MDA, all changes were significant. It may be concluded that erythrocyte functions of medium level trained middle-distance athletes return to their former situation 24 hours following a submaximal exercise.