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Alterations in human upper extremity motor function during acute exposure to simulated altitude
A J Hamilton1, L A Trad, A Cymerman
1Altitude Research Division, U.S. Army Research Institute of Environmental Medicine, Natick, MA 01760-5007.
Aviation, Space, and Environmental Medicine
|August 1, 1991
Summary
Mild motor dysfunction, specifically reduced arm speed, is linked to Acute Mountain Sickness (AMS). This study shows hypoxia impairs motor pathways, affecting speed but not accuracy in simulated high-altitude exposure.
Area of Science:
- Altitude physiology
- Neuroscience
- Motor control
Background:
- Acute Mountain Sickness (AMS) is a common condition at high altitudes.
- The relationship between mild AMS and motor function requires further investigation.
Purpose of the Study:
- To test the hypothesis that mild motor dysfunction is associated with AMS.
- To quantify arm movement characteristics during simulated high-altitude exposure.
Main Methods:
- 14 subjects underwent a 30-hour simulated altitude exposure (4,600 m).
- Arm movement characteristics were measured using a computerized upper extremity movement analyzer (UEMA).
- UEMA results were correlated with the Environmental Symptoms Questionnaire (ESQ) and neurologic examinations.
Main Results:
- Speed-related arm movement parameters significantly declined by 20-32% at altitude compared to sea level.
- Error indices in arm movements did not significantly change.
- Declines in arm speed strongly correlated with AMS symptom severity (R = 0.82).
Conclusions:
- Subclinical alterations in upper extremity speed are associated with mild, reversible AMS.
- Hypoxia may induce supraspinal inhibition of motor pathways, leading to reduced motor speed.