Title: “The Effect of Anxiety on Postural and Voluntary Motor Control”
Supervisor: Dr. Mark Carpenter (Kinesiology)
Second Reader: Dr. Romeo Chua (Kinesiology)
Abstract: Anxiety is known to have a significant effect on motor control, this has been documented in sports and music performance, postural control, and day to day tasks. The purpose of this thesis is to compare the effect of anxiety on postural control to that on voluntary motor control. Three domains were selected to make plausible comparisons: static balance, dynamic balance, and anticipatory postural adjustments (APA). A literature search was carried out where quiet stance was matched to upper body isometric precision tasks, dynamic balance was compared to corrective upper body movements, and APAs were compared to anticipatory patterns in voluntary upper body tasks. Anxiety was found to have a tightening effect on static balance in quiet stance while force fluctuations increased in isometric upper-limb precision tasks. In dynamic balance, anxiety acts to restrict whole-body responses to perturbations by increasing central nervous system (CNS) reactivity. In anticipatory postural adjustments, subjects leaned away from threats and reduced the magnitude and speed of the APA responses. Unfortunately, literature on the effects of anxiety on anticipatory and corrective upper body responses is limited, making direct comparisons with postural behaviours during similar tasks difficult. Overall, it seems that anxiety has a restricting effect on postural control, and a relaxing effect on voluntary motor control. This could be due to the higher stakes associated with postural control where reduced quality of performance can lead to a fall, where in upper body tasks there are no safety concerns. Future research is needed to further examine the effect of anxiety on upper body corrective and anticipatory responses.