Middle Cerebral Artery Blood Flow Velocity After Exposure to Sustained +Gz

摘要

Anecdotal information has been available for many years that G training over timeincreases a human's ability to tolerate G. However, little data exist to corroborate the observation. The main thrust of this study was to quantify the accumulative physiological effects of +Gz exposure on cerebral blood flow using transcranial Doppler. A total of six male and six female subjects participated in this study. The subjects experienced numerous G exposures ranging from 2.5 to 5.2 % during three days of centrift%ge training. Total time at i>1 was 5.3 minutes. Changes in middle cerebral artery blood flow velocity during a squat-stand orthostatic challenge test before and after G exposures and then within seven days after each day of G exposure were observed. No significant changes in middle cerebral artery blood flow velocity were found. Further studies with more subjects, higher levels, and more repeated exposures of longer duration are suggested.