Produced, edited, and copyrighted by
Professor Brent S. Rushall, San Diego State University
Volume 3, Number 4: May 17, 1996


The scientific evidence associated with altitude acclimatization and performance in elite swimmers is reviewed extensively in the yet-to-be-published paper, "Altitude training and elite swimmers." The authors are: Brent S. Rushall, Michael J. Buono, and Anthony A. Sucec, Professors of Exercise and Nutritional Sciences at San Diego State University, and Alan D. Roberts, Associate-Professor of Sports Studies at the University of Canberra. The article is the most detailed and up-to-date treatment of the topic available.

Initial attention is paid to the manner in which the human body acclimatizes (adapts) to passive and active stresses. Those reactions are then meshed with the published works on altitude acclimatization that are valid for swimming. With altitude training featuring as an expensive part of the annual plans of several nations, it is of value to consider the summary implications of this research article.

". . . acclimatization responses often are used as the theoretical justification for sea-level performance improvements. The reasoning is: improved oxygen transport at altitude must produce improved oxygen transport, and therefore physical performance, at sea-level. Yet only at altitudes in excess of 3,000 m do these changes occur fully and eventually. At those altitudes it is not possible to perform the volume and intensity of beneficial high-level training that can be accomplished at sea-level. That produces a dilemma: is it better to have (a) an altered physiology and less training volume and quality or (b) full training without the altered physiology? The evidence strongly suggests the latter. However, the implication for the physiological adaptations does not stop there. Since most "altitude" camps are conducted at low altitudes (e.g., in Australia they range from 1,600 to 2,000 m), acclimatization responses are not guaranteed to occur in their entirety or to their maximum level. Low altitude partial physiological acclimatization usually will not produce a physiological state that can be "theoretically" justified to improve sea-level performance.

Further problems arise with the concept of relatively brief exposures to low altitude training camps. If an athlete is responsive to the low hypoxic levels at such camps, considerable time will still be needed before all acclimation responses can be completed. Usually a three-week training camp will not produce beneficial physiological states (if they exist) but will only produce disruption to a normal training program. Consistent training stimuli will not be maintained because of: (a) travel to the camp, (b) initial shock reactions to the new mild hypoxic stimulus which reduces the capacity to train, and (c) continued compromised training programs that do not support either or both the intensity or volume of work that can be sustained by elite athletes at sea-level.

It is popular in some countries to conduct several short-term training camps at altitude as part of an annual training plan. Support for benefits from such plans is not available in the form of objective evidence. Essentially, they will amount to training interruptions accompanied by unrelated and partial stress acclimatizations which will be reversed upon return to non-hypoxic altitudes (e.g., sea-level). Despite what is known about acclimatization to training and altitude stresses, influential coaches persist with such usually expensive camps.

There is no objective justification for conducting low-altitude short-duration training camps with a view to deriving effects that will benefit sea-level performances in highly-trained swimmers."

The summary of the article is mainly in point form. Those points are listed below for their import is obvious.

"This paper has reported and interpreted research on altitude acclimatization and performance in highly-trained elite athletes. The major points determined are listed below.

  1. Exposure to altitude produces reactive changes which are only specific to altitude.
  2. Predominantly endurance performances at moderate altitude never reach levels that are possible at sea-level.
  3. The shorter the stay at altitude, the less marked and more transient will be any acclimatization changes.
  4. Physiological changes alone may be insufficient to fully enhance performance at altitude.
  5. The lower the altitude, the less marked will be the acclimatization response.
  6. Individuals vary greatly in their responsiveness to altitude stress. Some may never acclimate.
  7. The eventual physiological acclimatizations that are exhibited at altitudes of more than 3,000 m are:
    • increased ventilation and blood hemoglobin, and
    • enhanced oxygen extraction in the muscles.
    These changes need to be qualified.
    • Increased ventilation could be detrimental to performance during the transient re-introduction stage to sea-level.
    • Red blood cell volume may increase, if the exposure duration is greater than three to four weeks, but that association with an unchanged VO2max is not understood.
    • Changes at the cellular level are likely to be moderated by the severity of the altitude exposure.
  8. Stages of acclimatization take time. Less than one month is not likely to provoke a fully acclimated systemic response.
  9. Oxygen delivery at altitude is likely to be less than at sea-level even after full acclimatization.
  10. An athlete's physiology changes to acclimate to altitude but those changes do not support elevated sea-level performances.
  11. The metabolism in exercise and recovery changes at altitude (glycolytic activity is increased).
  12. Altitude training requires increased fluid, carbohydrate, and iron intake.
  13. The energy contributions at a particular swimming speed are different at altitude to those at sea-level.
  14. The neuromuscular skill patterns at a particular swimming speed are altered at altitude because of the need to recruit muscle fibers that provide energy through glycolysis.
  15. The economy of swimming movements at sea-level could be disrupted by the changes provoked by altitude acclimatization.
  16. The reduction in training volume and intensity associated with altitude acclimatization detracts from achieving peak sea-level performances.
  17. The opinions of experts and research results do not support any benefit to be gained from altitude training for sea-level performance in trained swimmers.
  18. Neither the principle of specific acclimatization nor the principle of specific training is accommodated by altitude training for sea-level performances.

These factors lead to the conclusion that altitude training is not an avenue for enhancing the sea-level performances of highly-trained swimmers. The practice of conducting altitude training camps for elite swimmers is not justified on either physiological grounds or performance benefits."

Return to Table of Contents for the Carlile Coaches' Forum.