Altitude training

Altitude training is a strategy that attempts to enhance athletic performance by taking into account the elevations at which athletes live, train, and compete. The theory behind it involves the physiological changes to the human body caused by high altitude environments (typically over 2,000 meters, or about 6,500 feet) compared to sea level, and how they impact endurance training. Although considerable research has been carried out into understanding the nature of these effects, known as hypoxic stress, the benefits of altitude training have not yet been conclusively proven. Nevertheless, altitude training has continued to increase in popularity with many elite athletes, coaches, and sporting organizations endorsing the practice. A range of different athletic training programs have been devised over the years in an attempt to attain the best results.

Background

The 1968 Summer Olympic Games were the seminal event for the popularization of altitude training as a means of enhancing athletic performance. The games were held in Mexico City at an elevation of about 2,300 meters (7,000 feet). While events requiring quick, explosive energy saw many strong performances, endurance events saw noticeable declines in performance. It was also noted that athletes from high altitude countries such as Ethiopia and Kenya appeared to perform better than their counterparts from lower areas, winning a relatively high proportion of the medals awarded for long and medium distance races.

These observations sparked an interest in altitude training among athletes, coaches, and sports scientists. Altitude training is now commonly employed in a wide range of sporting disciplines as a meaning of improving athletic performance. While some competitors adopted training at high elevations, no definite advantage was proved. In the 1990s several scientists proposed that essentially the opposite strategy—living at high altitude but training closer to sea level—could improve endurance, and presented some evidence. Some athletes and trainers endorsed this controversial "live high, train low" method, while others supported variants such as "live low, train high," "live high, train high," and intermittent hypoxic training.

Overview

All forms of exercise sustained longer than several minutes are aerobic, meaning that they require the body to generate energy with oxygen. Oxygen is taken in by breathing and carried to muscles by red blood cells. As altitude above sea level increases, there is a corresponding fall in the partial pressure of oxygen, or amount in the air. The body is believed to undergo a number of physiological responses in order to cope with effects of reduced oxygen availability, or hypoxia; this process is commonly known as acclimatization. Altitude training suggests that manipulating these states can lead to enhanced athletic performance.

One physiological response of acclimatization is the production of a hormone called erythropoietin (EPO). EPO increases the rate of production of red blood cells in bone marrow, resulting in an increase in maximal oxygen uptake (VO2 max). Theoretically, having more red blood cells can improve endurance performance. Exercising in a high altitude environment also leads to a short-term increase in heart rate and respiratory rate as the body attempts to cope with the lack of oxygen. Other changes that occur include increased hemoglobin concentration (which has been demonstrated to enhance an athlete’s performance), decreased oxygen saturation during exercises, and reduced plasma volume. Despite what is known about the effects of hypoxia, the precise mechanisms behind the possible benefits that result from altitude training are not yet fully understood and research in this area is ongoing.

"Live high, train high" is the original type of altitude training investigated in the wake of 1968 Mexico City Olympics. Some athletes sought to replicate the training conditions of relatively high-altitude Mexico City, which they felt had improved performance. A similar theory attempted to mimic the lifestyles of East African competitors who were known to both live and train at relatively high altitudes, allegedly giving them a competitive advantage not only in Mexico City but in general. In this form of altitude training athletes live, sleep, and train at a high altitude location for multiple weeks before competition. It aims to increase red blood cell volume while at the same time providing an additional training stimulus caused by tissue hypoxia. In cases where the competition takes place at high altitude, this training method produced clear advantages by acclimatizing athletes in advance. However, while some advocates suggest it causes general improvement in exercise performance in elite athletes, any performance enhancement in competition at sea level is controversial and unproven.

Athletes, trainers, and scientists have also researched the "live low, train high" method of altitude training. With this program, athletes live and sleep at a low altitude and train under the hypoxic conditions of a high altitude environment. This type of training is generally easier to implement than the other forms of altitude training, as less time is required in the hypoxic environment (whether an actual high-altitude place or a room, tent, or mask that simulates such conditions). There is a lack of scientific evidence to suggest that this type of training results in any performance gains for athletes, especially in normal, low-altitude competitions. It can even negatively affect training due to the lower exercise intensity level typically achieved.

The "live high, train low" form of altitude training, developed in an attempt to avoid the drawbacks of the other methods, is implemented by living at a high altitude location but training at a lower elevation. Like the other forms, it seeks to increase red blood cells, but it allows athletes to maintain high training intensity. Because it requires at least three weeks of living at high altitude for at least twelve hours each day to achieve acclimatization, this method can be logistically difficult for all but the most elite athletes. Yet it has the most evidence supporting an improvement in performance at sea level, making it the most popular form of altitude training. High-quality scientific studies of its benefits are still lacking, however.

Bibliography

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