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Publication AbstractsIntermittent Hypobaric Hypoxia Induces Altitude Acclimation and Improves the Lactate ThresholdMireia Casas, B.Sc., Héctor Casas, B.Sc., Teresa Pagés, Ph.D., Ramón Rama, Ph.D., Antoni Ricart, M.D., Josep L. Ventura, M.D., Jordi Ibáñez, M.D., Ferran A. Rodríguez, M.D., and Ginés Viscor, Ph.D.Aviat Space Environ Med 2000; 71:125-30 AbstractThe physiological responses to short-term intermittent exposure to hypoxia in a hypobaric chamber were evaluated. The exposure to hypoxia was compatible with normal daily activity. The ability of the hypoxia program to induce hematological and ventilatory adaptations leading to altitude acclimation and to improve physical performance capacity was tested. Six members of a high-altitude expedition were exposed to intermittent hypoxia and low-intensity exercise (in cycle-ergometer) in the INEFC-UB hypobaric chamber over 17 d, 3-5 h · d-1, at simulated altitude of 4,000 m to 5,500 m. Following this hypoxia exposure program, significant increases were found in packed cell volume (41 to 44.6%; p < 0.05), red blood cells count (4.607 to 4.968 106 cells · µL-1; p < 0.05), and hemoglobin concentration (14.8 to 16.4 g · dL-1; p < 0.05), thus implying an increase in the blood oxygen transport capacity. Significant differences in exercise blood lactate kinetics and heart rate were also observed. The lactate vs. exercise load curve shifted to the right and heart rate decreased, thus indicating an improvement of aerobic endurance. These results were associated with a significant increase in the ventilatory anaerobic threshold (p < 0.05). Significant increases (p < 0.05) in pulmonary ventilation, tidal volume, respiratory frequency, O2 uptake, CO2 output and ventilatory equivalents to oxygen (V(dot)E/V(dot)O2) and carbon dioxide (V(dot)E/V(dot)CO2) were observed at the ventilatory threshold and within the transitional zone of the curves. We conclude that short-term intermittent exposure to moderate hypoxia, in combination with low-intensity exercise in a hypobaric chamber, is sufficient to improve aerobic capacity and to induce altitude acclimation.Keywords: hypoxia, metabolic and ventilatory adaptations, hypobaric chamber, erythropoiesis, aerobic capacity. Information on subscribing, and on obtaining copies of an article or of an entire issue. Table of Contents for Volume 71, Number 2 of the ASME journal.
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