Final answer:
The effect of increased red blood cell production due to higher altitude training is better oxygen transport in the blood, improving an athlete's endurance. However, excessive RBC production can lead to increased blood viscosity, posing significant health risks such as strokes or heart attacks.
Step-by-step explanation:
The effect of increased red blood cell (RBC) production in response to athletes training at higher altitudes is enhanced blood oxygenation. At higher elevations, the air contains less oxygen, which leads to a decrease in the oxygen saturation of hemoglobin in the bloodstream.
In turn, the kidneys produce more of the hormone erythropoietin (EPO), which stimulates the production of additional RBCs from the bone marrow. As the number of RBCs increases, so does the hemoglobin and the body's capacity to transport oxygen, boosting the individual's endurance and performance.
However, this physiological response can lead to a condition known as polycythemia, where the blood volume is primarily excess RBCs, increasing the viscosity of the blood and potentially straining the cardiovascular system.
Using synthetic EPO or engaging in blood doping to artificially enhance athletic performance is particularly risky because of the increased blood viscosity. This can lead to issues like higher blood pressure and an increased risk of blood clots, which pose significant health risks including strokes, heart attacks, and thrombosis.