The Effects Of Altitude Training On Athletes

At the Mexico City Olympics, athletes who ha dpreviously set records in running events over 800 meters were beaten by athletes native to high altitudes. After such upsets, scientists began investigating physiological explanations for such wins. Studies using high-altitude athletic training investigate the effects of such training. High-altitude training affects the body's ventilation, heart rate, acid-base balance, composition and metabolism.

Ventilation

Ventilation is how well the oxygen from the atmosphere diffuses into the bloodstream from the lungs. The oxygen travels in the bloodstream into the cells within the body. An athlete's muscle cells use oxygen to produce energy during performance. According to a 1997 study by Levine and Stray-Gunderson in the "Journal of Applied Physiology," athletes living at altitudes more than 2,500 meters above sea level and training at low altitudes could acquire physiological advantages. The study showed increased red blood cell volume, which enables higher volumes of oxygen to reach cells during exercise. More oxygen and increased breathing rate decreases incidence of fatigue.

Heart Rate

Higher altitudes have decreased atmospheric pressure on the human body. Decreased pressure results in decreased oxygen diffusion through the lungs and into the bloodstream. The body compensates for the low oxygen by increasing the heart rate. A faster heart rate pushes the blood quicker, thus distributing oxygen to tissues in need. As the body acclimates to higher altitudes, the volume of oxygen carrying red blood cells increases, and the heart rate returns to normal.

Acid-Base Balance

Increased breathing rates, or ventilations, decrease the carbon dioxide in the blood of athletes training at high altitudes. Decreased carbon dioxide results in high blood pH and subsequent respiratory alkalosis. High pH is considered an alkaline condition. Since exercise produces lactic acid in muscles, the body's high-altitude pH counteracts such lactic acid-induced fatigue. Therefore, muscles do not tire as quickly. According to Phoebe Cheuk at the Curtin University of Technology, this increased buffering capacity enhances an athlete's performance after just two weeks of high-altitude training.

Body Composition

High altitude also changes the body's composition. Prolonged living at altitudes higher than 4,500 meters decreases muscle mass. Studies show weight loss of 100 to 200 g a day. Such weight loss occurs due to dehydration from hyperventilation. In those who suffer from altitude sickness, the appetite is depressed. Also, nutritional absorption is decreased in the intestines in high altitudes, and fecal losses contribute to weight loss

Metabolism

Carbohydrates yield a high number of ATPs per molecule of oxygen. ATP is used by the body for fuel. When training or living at high altitudes, a diet with at least 60 percent carbohydrates is recommended to counteract weight loss. If the diet is not adequate in carbohydrates, the body will use stored fats and proteins as an energy source. When the body uses its own protein as and energy source, it becomes inefficient. Such an inefficient supply of energy results in a loss of muscle mass and a poor performance.

Many types of hormones are stimulated by physical exercise and essential in metabolic regulation. Both cortisol and growth hormone have been shown to increase during high altitude training (See Reference #1). The appearance of certain hormones indicates over-training in athletes. Marco Zaccaria and colleagues at the University of Padua showed significant increases in water and salt regulating hormones, which may contribute to high altitude dehydration and increased red blood cell volume (See Reference #3).