The effects of acute normobaric hypoxia on standing balance while dual-tasking with and without visual input

Purpose To investigate the influence of acute normobaric hypoxia on standing balance under single and dual-task conditions, both with and without visual input. Methods 20 participants (7 female, 20–31 years old) stood on a force plate for 16, 90-s trials across four balance conditions: single-task (quiet stance) or dual-task (auditory Stroop test), with eyes open or closed. Trials were divided into four oxygen conditions where the fraction of inspired oxygen (F I O 2 ) was manipulated (normoxia: 0.21 and normobaric hypoxia: 0.16, 0.145 and 0.13 F I O 2 ) to simulate altitudes of 1100, 3,400, 4300, and 5200 m. Participants breathed each F I O 2 for ~ 3 min before testing, which lasted an additional 7–8 min per oxygen condition. Cardiorespiratory measures included heart rate, peripheral blood oxygen saturation, and pressure of end tidal ( P ET ) CO 2 and O 2 . Center of pressure measures included total path length, 95% ellipse area, and anteroposterior and mediolateral velocity. Auditory Stroop test performance was measured as response accuracy and latency. Results Significant decreases in oxygen saturation and P ET O 2 , and increased heart rate were observed between normoxia and normobaric hypoxia ( P