Phase one: Days 0-5. Training volume should be reduced 15-20% and intensities should remain below 150 bpm [EN-1 training intensity or less].

Phase two: Days 6-12. Training volume can be gradually increased as should intensity to match sea-level work. This phase is solely acclimatization and whether or not any real training adaptation occurs is questionable.

[Herein lies a problem. The first six days at altitude require reduced work. That constitutes a "disguised taper." That workload reduction is similar in impact to that afforded by sickness for athletes in very heavy training. In such situations athletes return to training and perform better even though they have been ill. Particularly for athletes who are at altitude for a short period of time (one to three weeks), the benefits of this initial "recovery" period may endure past the stay at altitude. Thus, improved performances at sea-level, which are traditionally ascribed to altitude training, may simply result from the "forced" recovery that is required as part of the adaptation process.]

Phase three: Days 13-21. It is doubtful that 21 days of altitude training leads to greater gains in training or performance capacity beyond those seen at sea-level. For the same category of sea-level work, altitude training will be at approximately 10 bpm higher. [The value of pace work being stimulated with unnatural, in sea-level terms, energy supply has to be questioned.]

Arriving Back at Sea-level

Days 0-3. There may be some advantage to performance (why is not known). All physiological parameters are stable. [Performance advantage may come from rested condition over that previously held at sea-level.]

Days 4-15. Adjustments in training and performance and physiological parameters. The readjustment demands compromise performance.

Days 16+. Training and performance are now enhanced and physiology is stable. The athlete has returned to being a sea-level trained individual.

Discussing what has been found at ICAR "In three years of altitude research comparing performance matched athletes training at sea-level and altitude (i.e., 6000 ft.) no significant physiological change could be found. There were, however, possible trends that may explain the potential gains as a result of altitude training. These included a potential increase in blood volume and buffering capacity. Additional work in these areas is still needed if we are to determine why altitude training may benefit performance."

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