Breathing Adjustment

• The first effect of training at high altitude is the speeding up of the heart rate and the respiratory rate. This is the body compensating for lower oxygen pressure. The body has to acclimatize to the high altitude and goes through a series of physiological changes, some of which happen almost immediately while others take several weeks. One significant early change is to the acid-base balance of the body, caused by the faster heart rate.
  
  

Lower Quality Performance

• With limited oxygen, athletes are extremely unlikely to reach the same performance levels they would expect at sea level. Studies have suggested athletes training at high altitudes generally see their speed of movement reduced by 10 to 15 percent. Trying too hard to increase their performance level often results in athletes suffering injuries or overtraining. As well as the trouble the human body has in adapting to high altitude, lower wind resistance also contributes to inferior performance.
  
  

Reduced Muscle Strength

• As a result of there being less oxygen to reach the muscles at altitude, weight loss is inevitable. This is because of the body's to consume muscle for energy. The effect of the body's adaptation to high altitude on the chemical makeup of the muscles can also lead to infection and reduce muscle strength further. Moreover, the higher the altitude, the greater the risk of malnutrition, which can lead to extreme weight loss.
  
  

Dehydration

• Mountain air is cool and dry, which can lead to the loss of a lot of water when training. Athletes must drink at least 3 liters of water per day to maintain standard hydration. Dehydration can also induce mountain sickness in some people. It is one symptom, alongside headache, malaise and reduced appetite of a condition that can lead to an emergency situation if the sufferer does not rest and drink plenty of fluids (not alcohol) or take medication.