The physiological effects of training under continuous or intermittent hypoxia on exercise performance are covered diversely. Scientific reasoning for the effect of altitude training became a new quality, since the hypoxic Signal cascade was discovered at the molecular level and the transcriptional factor HIF1 alpha had been described in its adaptive effects. Current trends, regarding the spread of altitude training centers allow a larger group of people constantly use of low-oxygen air mixtures as a training environment. In this context the present study describes changes of endurance performance under acute hypoxia. 12 runners and 18 cyclists were studied in normoxia (FiO2 20,9 %) and in an altitude chamber (Höhenbalance, Cologne) under acute normobaric hypoxic exposure at FiO2 15,0% and 17,0% (2.700m and 1,800 m above sea level). For all athletes, we observed a significant reduction of maximum power output and treadmill speed in hypoxia. The oxygen saturation and VO2 peak decreased significantly. In hypoxia, the lactate performance curves were shifted to the left. Regarding the heart rate at determined individual metabolic thresholds (LT, IAT) there were no differences between hypoxia and normoxia. Parameters of heart rate variety were also unchanged. It can be derived that hypoxic air-mixtures can trigger an increased stimulus on cardiopulmonary and metabotic system using a comparable motor load to normoxia. Regarding this, we recommend to use hypoxia not only for performance enhancement but for people with a reduced motor loading capacity. The unaffected heart rate at metabolic thresholds at the examined altitudes suggests the use for training management.
© Copyright 2011 Herzfrequenzvariabilität: Gesundheitsförderung - Trainingssteuerung - Biofeedback. Internationales Symposium am 29. und 30. Oktober.. Veröffentlicht von Feldhaus, Ed. Czwalina. Alle Rechte vorbehalten.