Does variability of footfall kinematics correlate with dynamic stability of the centre of mass during walking?

Ignasiak, Niklas König; Ravi, Deepak K.; Orter, Stefan; Nasab, Seyyed Hamed Hosseini; Taylor, William R.; Singh, Navrag B.

doi:10.1371/journal.pone.0217460

Cited by 11 publications

(17 citation statements)

References 47 publications

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“…BWS also reduces ML λ s pos and ML λ s vel , indicating greater local dynamic stability in the frontal plane than during free walking. Variability of step width [58] along with ML aCOM sway and its variability were also reduced, which is in line with the general belief that BWS per se already increases dynamic stability [72,77,78]. Along the sagittal plane, Kyvelidou et al found however increased λ s and kinematic variability of the hip, knee, and ankle angles during walking with BWS on a treadmill [79].…”

Section: Body Weight Support Effectssupporting

confidence: 68%

“…λ s is therefore especially suitable for detecting differences between position-timing dependent systems such as COM motion while walking [ 55 – 57 ]. λ s can be used as a proxy measure of freedom in ML COM motion [ 58 ]. A higher λ s indicates larger chaotic elements of a system, while λ s close to zero indicates a stable system [ 59 ].…”

Section: Methodsmentioning

confidence: 99%

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Mediolateral damping of an overhead body weight support system assists stability during treadmill walking

Bannwart

Bayer

Ignasiak

et al. 2020

J NeuroEngineering Rehabil

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Background: Body weight support systems with three or more degrees of freedom (3-DoF) are permissive and safe environments that provide unloading and allow unrestricted movement in any direction. This enables training of walking and balance control at an early stage in rehabilitation. Transparent systems generate a support force vector that is near vertical at all positions in the workspace to only minimally interfere with natural movement patterns. Patients with impaired balance, however, may benefit from additional mediolateral support that can be adjusted according to their capacity. An elegant solution for providing balance support might be by rendering viscous damping along the mediolateral axis via the software controller. Before use with patients, we evaluated if controlrendered mediolateral damping evokes the desired stability enhancement in able-bodied individuals. Methods: A transparent, cable-driven robotic body weight support system (FLOAT) was used to provide transparent body weight support with and without mediolateral damping to 21 able-bodied volunteers while walking at preferred gait velocity on a treadmill. Stability metrics reflecting resistance to small and large perturbations were derived from walking kinematics and compared between conditions and to free walking. Results: Compared to free walking, the application of body weight support per-se resulted in gait alterations typically associated with body weight support, namely increased step length and swing phase. Frontal plane dynamic stability, measured by kinematic variability and nonlinear dynamics of the center of mass, was increased under body weight support, indicating reduced balance requirements in both damped and undamped support conditions. Adding damping to the body weight support resulted in a greater increase of frontal plane stability. Conclusion: Adding mediolateral damping to 3-DoF body weight support systems is an effective method of increasing frontal plane stability during walking in able-bodied participants. Building on these results, adjustable mediolateral damping could enable therapists to select combinations of unloading and stability specifically for each patient and to adapt this in a task specific manner. This could extend the impact of transparent 3-DoF body weight support systems, enabling training of gait and active balance from an early time point onwards in the rehabilitation process for a wide range of mobility activities of daily life.

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Section: Body Weight Support Effectssupporting

confidence: 68%

Section: Methodsmentioning

confidence: 99%

Mediolateral damping of an overhead body weight support system assists stability during treadmill walking

Bannwart

Bayer

Ignasiak

et al. 2020

J NeuroEngineering Rehabil

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“…leg retraction) to counteract terrain perturbations during running ( Muller et al, 2016 ; Seyfarth et al, 2003 ; Daley et al, 2007 ). However, reflex-mediated feedback control (of, for example, foot placement: Ignasiak et al, 2019 ; Joshi and Srinivasan, 2019 ) may be predominantly involved in locomotion at slow speeds ( Marigold and Patla, 2005 ). Furthermore, it remains unclear how these mechanisms vary across different perturbation types and sizes.…”

Section: Introductionmentioning

confidence: 99%

Rhythmic auditory stimuli modulate movement recovery in response to perturbation during locomotion

Ravi

Bartholet

Skiadopoulos

et al. 2021

Journal of Experimental Biology

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The capacity to recover after a perturbation is a well-known intrinsic property of physiological systems, including the locomotor system, and can be termed resilience. Despite an abundance of metrics proposed to measure the complex dynamics of bipedal locomotion, analytical tools for quantifying resilience are lacking. Here, we introduce a novel method to directly quantify resilience to perturbations during locomotion. We examine the extent to which synchronizing stepping with two different temporal structured auditory stimuli (periodic and 1/f structure) during walking modulates resilience to a large unexpected perturbation. Recovery time after perturbation was calculated from the horizontal velocity of body's center of mass. Our results indicate that synchronizing stepping with 1/f stimulus elicited greater resilience to mechanical perturbations during walking compared to the periodic stimulus (3.3 seconds faster). Our proposed method may help to gain a comprehensive understanding of movement recovery behavior of humans and other animals in their ecological contexts.

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“…The results show that the small effect in AP mean gait stability was not different between the two walking modes. About 68% of extrapolated COM motion can be predicted using the step width and length from the current and four preceding steps [ 37 ]. Murray et al reported that during non-matched slow, preferred, and fast treadmill walking, subjects walked with shorter step lengths compared to overground [ 18 ].…”

Section: Discussionmentioning

confidence: 99%

Margin of Stability May Be Larger and Less Variable during Treadmill Walking Versus Overground

et al. 2021

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Margin of stability (MOS) is considered a measure of mechanical gait stability. Due to broad application of treadmills in gait assessment experiments, we aimed to determine if walking on a treadmill vs. overground would affect MOS during three speed-matched conditions. Eight healthy young participants walked on a treadmill and overground at Slow, Preferred, and Fast speed-matched conditions. The mean and variability (standard deviation) of the MOS in anterior-posterior and mediolateral directions at heel contact were calculated. Anterior-posterior and mediolateral mean MOS values decreased with increased speed for both overground and treadmill; although mediolateral mean MOS was always wider on the treadmill compared to overground. Due to lack of optic flow and different proprioceptive inputs during treadmill walking, subjects may employ strategies to increase their lateral stability on treadmill compared to overground. Anterior-posterior MOS variability increased with speed overground, while it did not change on treadmill, which might be due to the fixed speed of treadmill. Whereas, lateral variability on both treadmill and overground was U-shaped. Walking at preferred speed was less variable (may be interpreted as more stable) laterally, compared to fast and slow speeds. Caution should be given when interpreting MOS between modes and speeds of walking. As sagittal plane walking is functionally unstable, this raises the consideration as to the meaningfulness of using MOS as a global measure of gait stability in this direction.

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Does variability of footfall kinematics correlate with dynamic stability of the centre of mass during walking?

Cited by 11 publications

References 47 publications

Mediolateral damping of an overhead body weight support system assists stability during treadmill walking

Mediolateral damping of an overhead body weight support system assists stability during treadmill walking

Rhythmic auditory stimuli modulate movement recovery in response to perturbation during locomotion

Margin of Stability May Be Larger and Less Variable during Treadmill Walking Versus Overground

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