Abstract
Abstract
Beidleman, Beth A., Charles S. Fulco, Stephen R. Muza, Paul R. Rock, Janet E. Staab, Vincent A. Forte, Michael D. Brothers, and Allen Cymerman. Effect of six days of staging on physiological adjustments and acute mountain sickness during ascent to 4300 meters. High Alt. Med. Biol. 10:253–260, 2009.—This study determined the effectiveness of 6 days (d) of staging at 2200 m on physiologic adjustments and acute mountain sickness (AMS) during rapid, high-risk ascent to 4300 m. Eleven sea-level (SL) resident men (means ± SD; 21 ± 3 yr; 78 ± 13 kg) completed resting measures of end-tidal CO2 (Petco2), arterial oxygen saturation (Sao2), heart rate (HR), and mean arterial pressure (MAP) at SL and within 1 h of exposure to 4300 m in a hypobaric chamber prior to 6 d of staging at 2200 m (preSTG) and on the summit of Pikes Peak following 6 d of staging at 2200 m (postSTG). Immediately following resting ventilation measures, all performed submaximal exercise (∼55% of altitude-specific maximal oxygen uptake) for ∼2 h on a bicycle ergometer to induce higher levels of AMS. AMS-C, calculated from the Environmental Symptoms Questionnaire, was measured following 4 h and 8 h of exposure at preSTG and postSTG, and the mean was calculated. Resting Petco2 (mmHg) was unchanged from SL (39.8 ± 2.6) to preSTG (39.3 ± 3.0), but decreased (p < 0.05) from preSTG to postSTG (32.8 ± 2.6). Resting Sao2 (%) decreased (p < 0.05) from SL (97 ± 2) to preSTG (80 ± 4) and increased (p < 0.05) from preSTG to postSTG (83 ± 3). Resting HR (bpm) and MAP (mmHg) did not change in any of the test conditions. The incidence and severity of AMS-C decreased (p < 0.05) from preSTG (91 ± 30%; 1.05 ± 0.56) to postSTG (45 ± 53%; 0.59 ± 0.43), respectively. These results suggest that modest physiologic adjustments induced by staging for 6 d at 2200 m reduced the incidence and severity of AMS during rapid, high-risk ascent to 4300 m.
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