The direction of postural threat alters balance control when standing at virtual elevation
- PDF / 1,482,991 Bytes
- 11 Pages / 595.276 x 790.866 pts Page_size
- 34 Downloads / 179 Views
RESEARCH ARTICLE
The direction of postural threat alters balance control when standing at virtual elevation Tiphanie E. Raffegeau1 · Bradley Fawver1,3 · William R. Young2 · A. Mark Williams1 · Keith R. Lohse1 · Peter C. Fino1 Received: 10 May 2020 / Accepted: 31 August 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Anxiogenic settings lead to reduced postural sway while standing, but anxiety-related balance may be influenced by the location of postural threat in the environment. We predicted that the direction of threat would elicit a parallel controlled manifold relative to the standing surface, and an orthogonal uncontrolled manifold during standing. Altogether, 14 healthy participants (8 women, mean age = 27.5 years, SD = 8.2) wore a virtual reality (VR) headset and stood on a matched real-world walkway (2 m × 40 cm × 2 cm) for 30 s at ground level and simulated heights (elevated 15 m) in two positions: (1) parallel to walkway, lateral threat; and (2) perpendicular to walkway, anteroposterior threat. Inertial sensors measured postural sway acceleration (e.g., 95% ellipse, root mean square (RMS) of acceleration), and a wrist-worn monitor measured heart rate coefficient of variation (HR CV). Fully factorial linear-mixed effect regressions (LMER) determined the effects of height and position. HR CV moderately increased from low to high height (p = 0.050, g = 0.397). The Height × Position interaction approached significance for sway area (95% ellipse; β = − 0.018, p = 0.062) and was significant for RMS (β = − 0.022, p = 0.007). Post-hoc analyses revealed that sagittal plane sway accelerations and RMS increased from low to high elevation in parallel standing, but were limited when facing the threat during perpendicular standing. Postural response to threat varies depending on the direction of threat, suggesting that the control strategies used during standing are sensitive to the direction of threat. Keywords Anxiety · Sway · Fear of falling · Heart rate · Motor control · Virtual reality
Introduction
Communicated by Francesco Lacquaniti. Keith R. Lohse and Peter C. Fino are co-senior authors. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00221-020-05917-5) contains supplementary material, which is available to authorized users. * Tiphanie E. Raffegeau [email protected] 1
Department of Health and Kinesiology, University of Utah, 250 S 1850 E, Salt Lake City, UT 84112, USA
2
School of Sport and Health Science, The University of Exeter, Exeter, UK
3
US Army Medical Research Directorate-West, Walter Reed Army Institute of Research, Joint Base Lewis-McChord, Washington, USA
The anxiogenic effects of standing at high elevation are well documented. In addition to increased physiological arousal and levels of worry, anxiety is associated with decreased variability of postural sway, increased power–frequency of center of pressure oscillations, and a posterior trunk leanaway from the direction of threat (Adkin et al.
Data Loading...
