Exercise Performance of Sea-Level Residents at 4300 m After 6 Days at 2200 m

Abstract

Partial acclimatization resulting from staging attenuated the impairment in TT performance of SLR rapidly exposed to 4300 m. The close association between improved TT performance and changes in exercise SaO2, compared to a lack of association with changes in [Hb] or Hct, suggest ventilatory acclimatization may have been the major factor contributing to the performance improvement.

Effect of repeated normobaric hypoxia exposures during sleep on acute mountain sickness, exercise performance, and sleep during exposure to terrestrial altitude

“…All the values, responses, and rates of change also were within an expected normal range relative to previous studies that used similar groups of unacclimatized SL residents who did not undergo treatment before or while living under HH conditions (2,4,11,12,21,23,24,26,28). Collectively, these results indicate that there is little justification for using NH treatment prior to HH residence.…”

“…In all cases, when significant main effects or interactions were found, Newman-Keuls post hoc test was applied. Recent studies of similar experimental procedures using unacclimatized SL volunteers were consulted to determine appropriate sample sizes for the major hypothesis related to changes in PET CO 2 , AMS symptomatology, and exercise performance (3,12,23). It was assumed that sham treatment would have no effect on PET CO 2 and that the magnitude of changes in PETCO 2 induced by NH treatment would be similar to that induced by HH treatment of a similar cohort of six volunteers (2).…”

“…Ventilatory acclimatization (VEacc) can be characterized by the progressive decrease in the end-tidal PCO 2 (PET CO 2 ) that leads to an increase in arterial O 2 saturation (Sa O 2 ) during the first several days of moderate-to high-altitude residence [hypobaric hypoxia (HH), reduced barometric pressure (P B ) and 20.9% O 2 ] (7, 28). The enhanced oxygenation is closely linked with reduced acute mountain sickness (AMS) and improved exercise performance during HH residence (1,11,12,14). Some studies show that VEacc can also be induced by 1-4 h of HH exposure repeated daily at altitudes of 4,300 -4,500 m in as few as 7 days and that this method of HH exposure is as beneficial as continuous HH residence for reducing AMS and improving exercise performance (2, 4, 18).…”

Effectiveness of Preacclimatization Strategies for High-Altitude Exposure

“…6. The degree of ventilatory acclimatization induced during each of the strategies requiring HH, but not NH, was reflective of the degree of ventilatory acclimatization observed on the first day of exposure to the target altitude of 4300 m. This, in turn, was linked to the effectiveness of the preacclimatization strategy for reducing AMS and improving exercise performance at 4300 m (1Y3, 9,10,14). Thus, the degree of ventilatory acclimatization induced using HH strategies but not NH strategies may be a good predictor of subsequent physiological and functional outcomes at high altitudes.…”

“…A major advantage of using staging as a preacclimatization strategy before ascent to high altitudes, in contrast to direct and rapid exposure to the same elevation, is that staging induces at least partial acclimatization such that individuals typically will not experience severe AMS or as large of a decrement in exercise performance soon after they arrive at high altitudes (1,10). The term ''preacclimatization strategy'' will refer to approaches reviewed in this article that had the potential to attenuate AMS and the decrement in endurance exercise performance for the ensuing exposure to a target altitude of 4300 m.…”