What is meant by alttitude training for athelete?

Answer 1

If you train at a high altitude, for instance, in Calgary Alberta, your body will adapt.

Normally, at sea level, your bodies red blood cells can carry x amount of oxygen. As you go higher in sea level, these red blood cells will find it harder to carry that same amount. This is because as you go higher in altitude the air becomes thinner. The bodies red blood cells will adapt to this situation. They will become harder working and more efficient.

An athlete will train at higher altitudes because their bodies red blood cells will adapt to the thin air situation. This means that when they compete at lower altitude levels, their red blood cells will be able to carry more oxygen then someone who has not trained at a high altitude. This allows the athletes muscles to get more fuel (oxygen) and work harder.