Final answer:
High-altitude training enhances oxygen utilization by increasing erythrocyte and hemoglobin levels, improving endurance and athletic performance at altitude and sea level.
Step-by-step explanation:
Training at high altitudes benefits athletic performance both at altitude and upon returning to sea level. One significant benefit is the improvement of oxygen utilization. Due to the decreased atmospheric pressure and oxygen concentration at higher elevations, there's a reduction in the oxygen saturation of hemoglobin, prompting the body to adapt by increasing erythropoietin (EPO) production, which in turn leads to an increase in erythrocytes (red blood cells) and hemoglobin levels. With more erythrocytes and hemoglobin, there is enhanced capacity for oxygen transport despite the lower oxygen saturation per molecule. This physiological adaptation allows for greater oxygen delivery to tissues, thus enhancing endurance and performance, especially when the athlete returns to sea-level conditions where oxygen is more abundant.