Abstract
During exercise the cardiovascular system has to warrant substrate supply to working muscle. The main function of red blood cells in exercise is the transport of O2 from the lungs to the tissues and the delivery of metabolically produced CO2 to the lungs for expiration. Hemoglobin also contributes to the blood's buffering capacity, and ATP and NO release from red blood cells contributes to vasodilation and improved blood flow to working muscle. These functions require adequate amounts of red blood cells in circulation. Trained athletes, particularly in endurance sports, have a decreased hematocrit, which is sometimes called “sports anemia.” This is not anemia in a clinical sense, because athletes have in fact an increased total mass of red blood cells and hemoglobin in circulation relative to sedentary individuals. The slight decrease in hematocrit by training is brought about by an increased plasma volume (PV). The mechanisms that increase total red blood cell mass by training are not understood fully. Despite stimulated erythropoiesis, exercise can decrease the red blood cell mass by intravascular hemolysis mainly of senescent red blood cells, which is caused by mechanical rupture when red blood cells pass through capillaries in contracting muscles, and by compression of red cells e.g., in foot soles during running or in hand palms in weightlifters. Together, these adjustments cause a decrease in the average age of the population of circulating red blood cells in trained athletes. These younger red cells are characterized by improved oxygen release and deformability, both of which also improve tissue oxygen supply during exercise.
Highlights
The primary role of red blood cells is the transport of respiratory gasses
Results on cHb, Hct and red blood cell count in athletes and their comparison with values obtained in healthy, sedentary individuals are conflicting due to the fact that red blood cell volume and plasma volume (PV) change independently and due to the many factors affecting each of these parameters
The major determinant for O2 diffusion, cannot be compensated adequately by the above mentioned O2 transport mechanisms resulting in a decrease in performance with increasing degree of hypoxia (Cerretelli and DiPrampero, 1985). Taken together these results indicate that red blood cells support local vasodilation in tissues with a high O2 demand by directly mediating Nitric oxide (NO) release and enzymatic production and by release of adenosine triphosphate (ATP), which causes NO release from endothelial cells by mechanisms, which are greatly enhanced in exercise when shear stress is increased by increased blood flow, O2 is low due to increased consumption, and the increase in temperature
Summary
Medical Clinic VII, Sports Medicine, University of Heidelberg, Heidelberg, Germany. Reviewed by: Giovanni Lombardi, I.R.C.C.S. In endurance sports, have a decreased hematocrit, which is sometimes called “sports anemia.” This is not anemia in a clinical sense, because athletes have an increased total mass of red blood cells and hemoglobin in circulation relative to sedentary individuals. Exercise can decrease the red blood cell mass by intravascular hemolysis mainly of senescent red blood cells, which is caused by mechanical rupture when red blood cells pass through capillaries in contracting muscles, and by compression of red cells e.g., in foot soles during running or in hand palms in weightlifters Together, these adjustments cause a decrease in the average age of the population of circulating red blood cells in trained athletes.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
