Altitude training
There are some top athletes who usually go training to places with a high altitude, between 1,200 and 1,600 m, for several weeks before an important competition.
It is known that when training at altitude, where the air has less oxygen, our body reacts producing more red blood cells to be able to transport the least amount of oxygen faster.
On the day of the competition, the athlete's blood will have more red blood cells, which will bring more oxygen to his cells. This will offer them a better performance.
However, not all the athletes endure this type of training; it takes a few days of acclimatization and some of them feel really bad, until the point of having to abandon this kind of training.
It is highly advisable that the athlete is in good health because at these altitudes the ambient temperature is low and this can cause colds and flu; they should also drink plenty of liquids, fruit juices, and so on, and also they ought to take care of their diet, which has to be rich in iron since iron is also responsible for oxygen transport. It is not worth having many red blood cells if there is little iron in your blood.