UBC Theses and Dissertations
Influence of virtual heights on dynamic postural control Cleworth, Taylor
Fear of falling and fall risk are strongly related. As such, falls are a leading cause of injury among older adults. Therefore, there is a need to study how balance is influenced by fear and fear related factors. Previous research has shown that when healthy young adults are exposed to a postural threat, by standing at the edge of an elevated support surface, their postural control is altered in both static and dynamic situations. While responses to support surface rotations have been studied in a high postural threat scenario [Carpenter et al., 2004b], the effects of threat on dynamic responses to support surface translations, a more ecologically valid type of perturbation, have not yet been investigated. This is due to several safety and feasibility issues that preclude translating individuals at height. Virtual reality (VR) has been established as an effective means for simulating height-related postural threat and can therefore be used to avoid the limitations associated with translating subjects at physical height. The purpose of this study was to examine the influence of fear and anxiety on postural reactions to surface translations during exposure to virtual heights. Twenty-one healthy young adults experienced support surface translations in the forward and backward directions, while immersed in a low and then high height virtual environment. Postural responses were significantly affected by height. Specifically, muscle activity in the lower leg and arm, and COP peak displacements, were earlier and larger in response to backward perturbations. No changes were observed in the responses to forward perturbations. In conclusion, virtual heights significantly altered neuromuscular responses to translational perturbations. Virtual height was capable of eliciting responses similar to real height, and thus may be used as an alternative method in investigating fear and anxiety related balance deficits in populations with a known fear of falling.
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