Answer:
There is no short answer.
Step-by-step explanation:
Athletes such as runners may prefer to train at higher altitudes than the altitude they perform at. This is because the higher altitude increases the number of red blood cells in the athletes body thus providing the muscles with more oxygen which increases performance.
If the runner moves from Nebraska to Colorado which is at a higher altitude, she will see an increase to her aerobic performance in the first three months.
I hope this answer helps.