Low intensity exercise does not impact cognitive function during exposure to normobaric hypoxia

•Cerebral oxygenation declined in normobaric hypoxia followed by cognitive impairment.•Mood state was not altered during normobaric hypoxia.•Low intensity exercise did not alter cognitive performance during normobaric hypoxia.

Exposure to hypoxia is associated with cognitive impairment, mediated by cerebral deoxygenation. This can be problematic for individuals who perform mental tasks at high altitude. Eight healthy men completed two experimental trials consisting of 5 h of exposure to normobaric hypoxia (12.5% O2). In one of the experimental trials (Hypoxia) subjects remained resting in a seated position the entire 5 h; in the other experimental trial (Hypoxia and Exercise) subjects rested 2 h, cycled for 1 h at constant wattage (workload equivalent to 50% of altitude adjusted VO2max), then rested the last 2 h. Cerebral oxygenation was measured continuously via near-infrared spectroscopy and cognitive performance was assessed by Trail Making Test A and B. Cerebral oxygenation and cognitive performance both were impaired during exposure to hypoxia. In the Hypoxia and Exercise trial, subjects experienced further declinations in cerebral oxygenation without concomitant decreases in cognitive function. These data demonstrate that cognitive function declines during exposure to normobaric hypoxia and this decline is not exacerbated by low intensity exercise.