HYPOXIA AND HYPEROXIA DO NOT HAVE SYMMETRICAL EFFECTS WHEN COMPARED TO NORMOXIA
Uchimaru, J., Cao, Y., Takemura, H., Takahasi, H., & Suzuki, S. (2014). Effects of acute hypoxia and hyperoxia on oxygen uptake and muscle oxygenation during incremental exercise. Medicine & Science in Sports & Exercise, 46(5), Supplement abstract number 1572.
This study focused on the effect of acute hypoxia and hyperoxia on oxygen uptake and muscle oxygenation during exercise in healthy males (N = 10). Ss performed an incremental maximal exercise test (15W/minute step) under normoxia (20.9 FIO2), acute hypoxia (14.5% FIO2), and acute hyperoxia (28.0% FIO2) conditions. The order of each condition was randomized and trials were three days apart. Peak oxygen uptake was measured during the incremental exercise. Near-infrared spectroscopy was used to monitor concentration changes of oxy- and deoxyhemoglobin in the left vastus lateralis muscle. Changes in total hemoglobin and StO2 were calculated and used as index of change in regional blood volume.
As expected, VO2peak decreased in acute hypoxia and increased in hyperoxia compared to normoxia values. Muscle oxygenation dropped progressively during acute hypoxia. On the other hand, changes in muscle oxygenation during hyperoxia were similar to normoxia values. Changed muscle oxygenation was greatest in acute hypoxia compared to normoxia and hyperoxia values.
Implication. Acute hypoxia decreased oxygen uptake with decreased muscle oxygenation. It is unlikely that changes in muscle oxygenation were related to increased oxygen uptake in hyperoxia, despite a similar change in absolute PO2 from hypoxia or hyperoxia to normoxia.
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