Final Answer:
An elite marathon runner would likely benefit from increased oxygen carrying capacity in the blood from the use of erythropoietin (EPO), which would serve to enhance endurance and overall athletic performance.
Step-by-step explanation:
Erythropoietin (EPO): This hormone stimulates the production of red blood cells in the bone marrow. Increased red blood cell count means more oxygen can be transported to muscles during exercise, improving aerobic capacity.
Enhance Endurance: EPO boosts the oxygen-carrying capacity of the blood, improving endurance by supplying muscles with more oxygen. This is crucial in marathon running, where sustained aerobic activity is essential.
Overall Athletic Performance: Improved oxygen delivery enhances an athlete's overall performance, as it delays fatigue and allows for more prolonged, intense effort. In the context of marathon running, this translates to better race times and greater efficiency.