Postural sway in near fallers: effects of fatigue and distraction

Author: Nicky Baker

  • Thesis download: available for open access on 24 May 2024.

Baker, Nicky, 2022 Postural sway in near fallers: effects of fatigue and distraction, Flinders University, College of Nursing and Health Sciences

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Near falls are more frequent than, and a precursor to, falls. Near falls are any momentary loss of balance where corrective action prevented a fall. Near falls and falls result from disruptions to postural control. While there is good understanding of postural control from birth through childhood into young adults, and in older adulthood from age 65 years, there is little known about balance in midlife from aged 40 to 65 years. During midlife, people are at risk of covert functional decline that is predominantly related to the physical function factors of muscle mass, strength, and balance.

The control of balance relies on these physical factors and the sensory systems. Balance control is exhibited as changes in postural sway and function. Confounders to balance control include distraction and fatigue. The aims of this research were to 1. understand the contributing factors for near falls, 2. to investigate differences in postural sway between near fallers and non-fallers, under normal, distracted and fatigued conditions, and 3. determine the utility of postural sway to predict near falls. Preparatory work identified clinical balance tests to discriminate near fallers from non-fallers.

Based on previous research with a similar community-based midlife population, near fallers were 2-3 times more likely to fail single leg stance, lunge and five tandem steps forwards than non-fallers. While these clinical tests provided a pass/fail measure of balance, they provided no detail, such as sway direction or magnitude. A scoping review of systematic reviews explored the instrumentation suitable for measuring postural sway in a community setting. A subsequent systematic review found that inertial sensors provided a valid and reliable option to measure postural sway in the community.

Consequently a longitudinal study measured balance outcomes and postural sway using the identified tests in healthy, midlife, community dwelling, non-faller or near faller adults. An initial survey provided self-report measures on demographics, quality of life, hearing, vision and dizziness to answer the study’s first aim. Then balance was tested in single leg stance, lunge and tandem steps, while confounding with distraction or fatigue. Distraction consisted of serial subtraction or categorical naming tasks concurrently with the balance task. Fatigue of the legs occurred following the incremental shuttle walk test. Sway was synchronously measured by a wearable inertial sensor taped to L4. Following the balance testing session, participants completed a daily near falls/falls diary for three months. Outcomes of the diary allocated participants to one of near faller, non-faller, or faller groups.

My unique contributions to knowledge are the explanation of balance using postural sway data in midlife adults; identifying the predictive variables to distinguish near fallers from non-fallers; and determining the differences in postural sway between near fallers and non-fallers.

Keywords: near falls; postural sway; inertial sensor; fatigue; distraction

Subject: Health Sciences thesis

Thesis type: Doctor of Philosophy
Completed: 2022
School: College of Nursing and Health Sciences
Supervisor: Professor Sue Gordon