Wilhite, D. P., Laymon, A. S., McKenzie, J. M., Lundgren, E. A., & Chapman, R. F. (2009). Maximal oxygen consumption changes after altitude training: Role of ventilatory acclimatization. ACSM 56th Annual Meeting, Seattle, Washington. Presentation number 2357.

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"With chronic altitude training, ventilatory acclimatization often results in an increase in maximal exercise ventilation. The added respiratory muscle work may contribute to the VO2max increase seen in many elite endurance athletes after altitude training." This investigation determined the contribution of respiratory muscle oxygen consumption to the change in VO2max after altitude training. Elite endurance runners (M = 6; F = 1) participated in a 28-day altitude training intervention in Flagstaff, Arizona (elevation 2,150 m) following a "live-high, train-low" training model. VO2max and VEmax were measured 2-9 days prior to departure for altitude and 1-2 days after returning to sea level. Respiratory muscle VO2 was estimated.

VO2max and VEmax increased from pre-altitude to post-altitude. Respiratory muscle VO2 increased from maximal exercise at pre-altitude to post-altitude. Of the 210 mL/min increase in VO2max with altitude training, an estimated 38 mL/min or 18.2% of the whole body increase in VO2max came from the increased metabolic cost of ventilation. These results suggest that ventilatory acclimatization plays a role in maximal oxygen consumption improvements with altitude training. It is unknown if a) the added respiratory VO2 after altitude training effectively limits the potential magnitude of locomotor VO2max increase, or b) if VO2max would change over time at sea level as ventilatory acclimatization decays. These issues may be of importance to elite endurance athletes, regarding the timing of key competitions after an altitude training camp.

Implication. The cost of acclimatized ventilation contributes to the noted changes in VO2max that result from prolonged exposure to altitude. [This explains why performances do not improve despite changes in VO2max.]

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