Roshanth Rajachandrakumar1, Jotvarinder Mann2, Alison Schinkel-Ivy3, Avril Mansfield4. 1. Toronto Rehabilitation Institute, University Health Network, 550 University Ave., Toronto, ON, Canada; Rehabilitation Sciences Institute, University of Toronto, 500 University Ave., Toronto, ON, Canada. 2. Toronto Rehabilitation Institute, University Health Network, 550 University Ave., Toronto, ON, Canada; Department of Kinesiology, University of Waterloo, 200 University Ave. W, Waterloo, ON, Canada. 3. School of Physical and Health Education, Schulich School of Education, Nipissing University, 100 College Drive, North Bay, ON, Canada. 4. Toronto Rehabilitation Institute, University Health Network, 550 University Ave., Toronto, ON, Canada; Evaluative Clinical Sciences, Hurvitz Brain Sciences Research Program, Sunnybrook Research Institute, 2075 Bayview Ave., Toronto, ON, Canada; Department of Physical Therapy, University of Toronto, 500 University Ave., Toronto, ON, Canada. Electronic address: avril.mansfield@uhn.ca.
Abstract
BACKGROUND: There are competing perspectives in the literature regarding the role of movement variability in quiet standing and balance control. Some view high variability as indicative of poor balance control and a contributor to increased fall risk, whereas others view variability as beneficial in providing sensory information that aids balance control. RESEARCH QUESTION: This study aimed to help to clarify the role of variability in balance control by testing two competing hypotheses: that increased variability would lead to instability, or that increased variability would improve stability, where stability is defined as the ability to respond to a perturbation. METHODS: Fourteen healthy young adults (20-35 years old) were recruited. Participants experienced postural perturbations of varying magnitudes, delivered via sudden backward movement of the support surface. Magnitudes of postural perturbation were chosen such that both step and no-step responses could be observed at each magnitude. Variability in the centre of mass and centre of pressure movement was measured for 10 s prior to the postural perturbation. Multiple regression was used to determine if movement variability predicted step responses when controlling for perturbation magnitude, trial order, and margin of stability at perturbation onset. RESULTS: Lower variability in medio-lateral centre of mass and centre of pressure position, and lower variability in medio-lateral centre of pressure velocity were related to increased odds of stepping in response to the perturbation (p-values ≤0.001). SIGNIFICANCE: This study provides support for the hypothesis that, at least for relatively low variability values, increased centre of pressure and mass movement variability improves stability. Specifically, increasing movement of the centre of pressure and mass in the medio-lateral direction may help to preserve stability in the antero-posterior direction by providing the central nervous system with information about the antero-posterior centre of mass across a wide range of medio-lateral positions.
BACKGROUND: There are competing perspectives in the literature regarding the role of movement variability in quiet standing and balance control. Some view high variability as indicative of poor balance control and a contributor to increased fall risk, whereas others view variability as beneficial in providing sensory information that aids balance control. RESEARCH QUESTION: This study aimed to help to clarify the role of variability in balance control by testing two competing hypotheses: that increased variability would lead to instability, or that increased variability would improve stability, where stability is defined as the ability to respond to a perturbation. METHODS: Fourteen healthy young adults (20-35 years old) were recruited. Participants experienced postural perturbations of varying magnitudes, delivered via sudden backward movement of the support surface. Magnitudes of postural perturbation were chosen such that both step and no-step responses could be observed at each magnitude. Variability in the centre of mass and centre of pressure movement was measured for 10 s prior to the postural perturbation. Multiple regression was used to determine if movement variability predicted step responses when controlling for perturbation magnitude, trial order, and margin of stability at perturbation onset. RESULTS: Lower variability in medio-lateral centre of mass and centre of pressure position, and lower variability in medio-lateral centre of pressure velocity were related to increased odds of stepping in response to the perturbation (p-values ≤0.001). SIGNIFICANCE: This study provides support for the hypothesis that, at least for relatively low variability values, increased centre of pressure and mass movement variability improves stability. Specifically, increasing movement of the centre of pressure and mass in the medio-lateral direction may help to preserve stability in the antero-posterior direction by providing the central nervous system with information about the antero-posterior centre of mass across a wide range of medio-lateral positions.
Authors: Charles S Layne; Christopher A Malaya; Akshay S Ravindran; Isaac John; Gerard E Francisco; Jose Luis Contreras-Vidal Journal: Front Hum Neurosci Date: 2022-07-15 Impact factor: 3.473