Effect of body iron stores on indices of biosynthesis and destruction of red blood cells after a single session of cycling exercise

Objectives : The present study investigates the effects of body iron stores upon indices of biosynthesis and destruction of red blood cells (RBC) induced by a single session of cycling exercise. Design: Eight sedentary female students were divided into groups depending on their body iron stores : normal (C group, n=5) and iron deficient (D group, n=3). Blood samples were collected at five time points of before (pre), immediately after (0 hours), then 1, 3 and 6 hours after exercise (248+/-31 kcal, 70% V(overdot)O-2 peak level). Osmotic fragility and serum haptoglobin (hp) concentration served as of for degradation, and delta-aminolevulinate dehydratase (ALAD) activity, erythropoietin concentration and number of reticulocytes served as indices of RBC biosynthesis. Results : A single session of cycling exercise did not affect the level of RBC, hemoglobin, hematocrit, serum iron, ferritin, transferrin saturation, hp and osmotic fragility in either groups. The delta-ALAD activity increased at 3 (p<0.05) and 6 hours (p<0.01) after exercise compared with that at 0 hours in the C group. In contrast, delta-ALAD activity in the D group was significantly lower at 3 hours after exercise than that of C group (p<0.001). Reticulocytes and erythropoietin concentration increased gradually in the C group after exercise, but not in the D group. Conclusions : A single session of cycling exercise under our experimental conditions enhanced RBC biosynthesis indicated by delta-ALAD activity, whereas exercise-induced hemolysis was not evident. Body iron stores affect the delta-ALAD activity induced by a single bout of cycling exercise.