Title

Effects of normobaric hypoxia on equilibrium and sensory organization

Document Type

Presentation

Journal/Book Title/Conference

Poster session at 62nd Annual Meeting of the American College of Sports Medicine (ACSM)

Publisher

Wolters Kluwer

Location

San Diego, CA

Publication Date

5-1-2015

DOI

10.1249/01.mss.0000478360.63277.81

Abstract

Dizziness or lightheadedness is a common symptom following rapid ascent to high altitude, which could result in diminished equilibrium. However, the effect of hypoxia on balance has not been well studied. PURPOSE: Compare the effects of varying levels of nomobaric hypoxia on equilibrium and sensory organization before and after exercise. METHODS: Following a familiarization trial, 12 males (27.3 ± 7.1 y) completed 3 sessions on a NeuroCom SMART Balance Master. This device provided an assessment of the sensory and motor control of balance on either a stable or unstable surface and in a stable or dynamic visual environment. A composite equilibrium score was determined. Additionally, information on somatosensory, visual, and vestibular responses was obtained. The 3 sessions were performed under 3 altitude conditions: a sham trial at the ambient altitude of 1400 m (LOW) and simulated altitudes of 3000 m (MID) and 5000 m (HIGH) created by a hypoxic generator. The order of the 3 altitude sessions was randomized. Each session consisted of 20 min of rest followed by the NeuroCom test, then 10 min of exercise (5 min walking at 3 mph and 5 min running at 6 mph) followed by a second NeuroCom test, all while connected to the hypoxic generator. Mean differences were identified with a two-way (pre/post exercise and altitude condition), repeated-measures ANOVA. RESULTS: The composite equilibrium score was significantly lower (p < 0.001) during the HIGH condition (73.4 ± 12.0) compared to the LOW (80.8 ± 7.0) and MID (84.1 ± 5.0) altitudes. Exercise had no additional influence on balance as the pre-exercise and post-exercise scores were not different (p = 0.91). The inability to ignore inaccurate visual cues in a situation of visual conflict was the most common error in the sensory analysis during the HIGH trials. CONCLUSIONS: Moderate hypoxia does not affect balance, but severe hypoxia significantly reduces equilibrium. Furthermore, it appears that the alterations in equilibrium are primarily from impairments in visual function.

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