Final answer:
Oxygen deficiency leads to EPO secretion by the kidneys to increase red blood cell production, restoring oxygen levels. Trained individuals adapt more efficiently to changes in oxygen demand. Excess Post-Exercise Oxygen Consumption (EPOC) helps in recovery after strenuous activity, with trained individuals often having a greater EPOC response.
Step-by-step explanation:
Oxygen deficiency (hypoxemia) occurs when there is a lower than normal level of oxygen in the blood, usually caused by inadequate oxygen in the environment, such as at high altitudes, or a medical condition that affects oxygen absorption or delivery to the tissues. When there is a deficiency in oxygen, the kidneys detect this and secrete erythropoietin (EPO), which in turn stimulates the production of red blood cells (erythrocytes) in the bone marrow, enhancing the oxygen-carrying capacity of the blood. As oxygen levels are restored, EPO secretion diminishes in a negative-feedback loop maintaining homeostasis. Trained individuals typically have an adapted response, with improved oxygen utilization and efficiency in their tissues, and may have a more finely tuned production of EPO, which helps them adapt more readily to changes in oxygen demand or availability.
Furthermore, Excess Post-Exercise Oxygen Consumption (EPOC) is the increased rate of oxygen intake following strenuous activity intended to erase the body's "oxygen debt." Physically trained individuals often have a greater EPOC response due to their ability to take up more oxygen and recover more quickly from exercise.