The Effect of Athletic Training on the RBC Count

Athletes are constantly putting their body through high demand exercise routines, pushing their muscles to the limits of aerobic respiration. When you place large demands on your muscles, they rapidly use up the oxygen delivered by the blood, at this point they switch to anaerobic, or without oxygen, respiration. The condition of decreased oxygen content in tissue is known as hypoxia. Athletes frequently experience episodes of hypoxia during exercise, which ultimately plays a role in the development of red blood cells, or RBCs.

  1. Effects of Hypoxia

    • Low blood oxygen is not a sustainable situation. There are sensors located in your kidney designed specifically to detect the level of oxygen in your blood. When blood oxygen levels significantly drop, these cells in your kidney will respond by producing a molecule known as erythropoietin.

    Effects of Erythropoietin

    • Your body responds to the highly aerobic demands you place on it

      Acting as the effector in the feedback system, erythropoietin travels in the blood away from the kidneys and acts to increase red blood cell production. The molecule has its effect in the bone marrow, the origin of RBCs, by inducing the proliferation of these specialized oxygen carrying cells. The logic for this response lies in the hope that by increasing red cell mass, the oxygen carrying capacity of the blood will be sufficient to combat the hypoxia.

    Evidence

    • If you consider other examples of hypoxic conditions you will see the connection between low blood oxygen and increased erythropoietin. For instance, in patients with COPD, or Chronic Obstructive Pulmonary Disease, their ability to saturate their blood with oxygen is significantly impaired because of lung disease. This leads to a chronic state of hypoxia, or low oxygen, in their tissues. This also leads to increased erythropoietin production, as well as the accompanying increase in red blood cell count. The same process is at work in athletes, however the root cause of the hypoxia is different.