Contents 1 Background History 2 Principles 3 Physiological Adaptations 4 References

[edit] Background History

The study of altitude training was heavily delved into following the1968 Olympics, which took place in Mexico City, Mexico: elevation 7,349 ft. It was during these Olympic Games that endurance events saw significant below-record finishes and anaerobic, sprint events broke all types of records (1). It was speculated prior to these events how the altitude might affect performances of these elite, world class athletes and most of the conclusions drawn were equivalent to those hypothesized: that endurance events would suffer and that short events would not see significant negative changes. This was attributed not only to less resistance during movement-due to the less denser air (10)-but also the anaerobic nature of the sprint events. Ultimately, these games inspired investigations into altitude training from which unique training principles were developed with the hope of avoiding underperformance.

[edit] Principles

Athletes or individuals who wish to gain a competitive edge for endurance events tend to take advantage of exercising at altitude due to the physiological changes that occur from the environmental differences compared to that at sea level. High altitude is typically defined as any elevation above 5,000 ft (1500 m). It is further broken down that elevations above 11,500 ft (3500 m) are very high altitude and elevations at or above 18,000 ft (5500 m) are extreme altitude. The differences between sea level and high altitude are characterized by the density of air and atmospheric pressure. At sea level, air is extremely dense due to higher atmospheric pressure, which results in more molecules of gas per liter of volume air. At levels of high altitude, the atmospheric pressure is less dense, resulting in less molecules of gas per liter of volume air. This leads to a decrease in partial pressures of gases in the body, which elicits a variety of physiological changes in the body that occur at altitude (2).

One suggestion for optimizing adaptations and maintaining performance is the live high, train low principle. This training idea emphasizes living at higher altitudes in order to experience the physiological adaptations that occur, such as increased Erythropoietin(EPO) levels, increased Red Blood Cell levels, and higher VO2 max, while maintaining the same exercise intensity at sea level. Due to the environmental differences at altitude, it may be necessary to decrease the intensity of workouts. Studies examining the live high, train low theory have produced varied results, which may be dependent on a variety of factors such as individual variability, time spent at altitude, and the type of training program (3, 4). For example, it has been shown that athletes performing primarily anaerobic activity do not necessarily benefit from altitude training as they do not rely on oxygen to fuel their performances.

[edit] Physiological Adaptations

While performing endurance activities it has been observed that maximal and submaximal aerobic power and capacity decreases with increasing elevation. Submaximal endurance activities at altitude reveal an increase in heart rate and respiratory ventilation in order to compensate for the lesser availability of oxygen (5). At altitude there is a decrease in oxygen hemoglobin saturation. In order to compensate for this, Erythropoietin (EPO), a hormone secreted by the kidneys, stimulates red blood cell production from bone marrow in order to increase hemoglobin saturation and oxygen delivery. While EPO is naturally occurring in the body, it is also made synthetically to help treat patients suffering from kidney failure and during chemotherapy. Over the past thirty years EPO has become popularly abused by competitive athletes through blood doping and injections in order to gain advantages in endurance events. Abuse of EPO, however, increases RBC counts beyond normal levels (polycythemia) and increases the viscosity of blood possibly leading to hypertension and increasing the likelihood of a blood clot, heart attack or stroke. Though at altitude it is known EPO stimulates production of RBC’s, it is uncertain how long this adaptation takes as various studies have found different conclusions based on the amount of time spent at altitude (6). One study concluded that individuals who lived at sea level and came to live at altitude had lower VO2max’s compared with individuals who had lived at high altitude their entire lives (7). This implies a more significant adaptation to altitude in individuals who have been at high elevations for most of their lives, allowing for more complete adaptations. It has also been found that VO2max decreases with increasing altitude. One study concluded that this decrease in VO2 at altitude is likely due to the decrease in arterial oxygen saturation, possibly causing a decrease in cardiac output (8). This decrease in cardiac output occurs as a means to compensate for the decreased availability of oxygen to the working muscles. In addition to cardiovascular and respiratory adaptations, significant changes in the musculature have also been observed with altitude adjustments. In a study comparing rats active at altitude versus rats active at sea level, with two sedentary control groups, it was observed that muscle fiber types changed according to homeostatic challenges which led to an increased metabolic efficiency during the beta oxidative cycle and citric acid cycle, showing an increased utilization of ATP for aerobic performance (9).

[edit] References

(1) Olympic.org-Official Website of the Olympic Movement. http://www.olympic.org/en/content/Olympic-Games/All-Past-Olympic-Games/Summer/Mexico-City-1968

(2) A High Altitude Resource: http://www.altitude.org/index.htm

(3) Levine, B.D., and J. Stray-Gunderson. 2001. The effects of altitude training are mediated primarily by acclimatization rather than by hypoxic exercise. Advances in Experimental Medicine and Biology 502: 75-88

(4) Stray-Gundersen J., Chapman R.F., Levine B.D. 2001. “Living high-training low" altitude training improves sea level performance in male and female elite runners. Journal of Applied Physiology 91: 1113 - 1120.

(5) Pugh, L. G. C. E., Gill, M. B., Lahiri, S., J. Milledge, S., Ward, M. P., and West, J. B. 1964. Muscular exercise at great altitudes. Journal of Applied Physiology 19: 431 - 440.

(6) Rupert, J. L., and P. W. Hochanchka. 2001. Genetic approaches to understanding human adaptation to altitude in the Andes. Journal of Experimental Biology 204 (pt 18): 3151-60.

(7) Frisancho, A.R. 1973. Influence of Developmental adaptation on aerobic capacity at high altitude. Journal of Applied Physiology 34:176-80.

(8) Kollias, J. 1968. Work capacity of long-time residents and newcomers to altitude. Journal of Applied Physiology 64: 1486-92.

(9) Bigard, A. X., Brunet, A., Guezennec, C. Y. and Monod, H. 1991. Skeletal muscle changes after endurance training at high altitude. Journal of Applied Physiology 71: 2114 – 2121.

(10) Ward-Smith. 1983. The influence of aerodynamic and biomechanical factors on long jump performance. Journal of Biomechanics 16: 8: pg:655 -658.