BACKGROUND: We live in an everchanging environment, whereby dynamic postural reaction time, the ability to adapt to environmental changes quickly and efficiently, is vital to overall safety. Visual cues influence human balance; however, without visual feedback, blind people must rely on their sensory feedback differently when responding to a stimulus. The purpose of the study was to investigate the relationship between standing postural sway and reaction time tasks using an auditory stimulus. METHODS: Five blind people with an average age of 29 and BMI of 30.9 participated in the study. Complex auditory (stimulus presented as “left”, tap “right” foot) reaction time tasks were performed with participant’s eyes open (EO). Reaction time (initiation of stimulus to start of physical movement), movement time (initiation of physical movement to completion of task) and overall response time (initiation of stimulus to completion of task) were calculated using the anterior-posterior (AP) center of pressure (COP) data for each task. The start of the response was determined at the instance the COP exceeded the mean three-standard deviations. The response end was determined based on a 10-N cut-off applied to the vertical ground reaction force used to detect the foot tap. In addition, COP was recorded during 30-seconds of quiet standing under two conditions: EO and eyes closed (EC) 30-second. Peak deviation z-scores and counts of COP exceeding two standard deviations (2STD) of the mean were calculated for EO and EC conditions. Pearson correlations were computed to assess the relationship between performance (i.e., reaction, movement, and overall response times) of the reaction task and 1) COP peak sway deviation z-scores and 2) the counts COP during EO and EC quiet standing. The significance level was set at 0.01. RESULTS: There were no significant relationships between COP deviation z-scores during EO and EC standing conditions and reaction, response, or movement time (all p> 0.01). Counts of COP exceeding 2STD during EO was very strongly correlated to reaction time (r: 0.98, p=.001). CONCLUSION: Only reaction time, specifically COP in the medial lateral direction, was significantly correlated to postural sway. This may be due to postural reaction time tasks commonly being initiated in the medial-lateral direction. However, given the rare population, more research is necessary to better understand this relationship.

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