The validation of new phase-dependent gait stability measures: a modelling approach

Identification of individuals at risk of falling is important when designing fall prevention methods. Current measures that estimate gait stability and robustness appear limited in predicting falls in older adults. Inspired by recent findings on changes in phase-dependent local stability within a gait cycle, we devised several phase-dependent stability measures and tested for their usefulness to predict gait robustness in compass walker models. These measures are closely related to the often-employed maximum finite-time Lyapunov exponent and maximum Floquet multiplier that both assess a system's response to infinitesimal perturbations. As such, they entail linearizing the system, but this is realized in a rotating hypersurface orthogonal to the period-one solution followed by estimating the trajectory-normal divergence rate of the swing phases and the foot strikes. We correlated the measures with gait robustness, i.e. the largest perturbation a walker can handle, in two compass walker models with either point or circular feet to estimate their prediction accuracy. To also test for the dependence of the measures under state space transform, we represented the point feet walker in both Euler–Lagrange and Hamiltonian canonical form. Our simulations revealed that for most of the measures their correlation with gait robustness differs between models and between different state space forms. In particular, the latter may jeopardize many stability measures' predictive capacity for gait robustness. The only exception that consistently displayed strong correlations is the divergence of foot strike. Our results admit challenges of using phase-dependent stability measures as objective means to estimate the risk of falling.

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The validation of new phase-dependent gait stability measures: a modeling approach

10.1101/2020.06.18.156950 ◽

2020 ◽

Cited By ~ 1

Author(s):

Jian Jin ◽

Dinant Kistemaker ◽

Jaap H. van Dieën ◽

Andreas Daffertshofer ◽

Sjoerd M. Bruijn

Keyword(s):

Fall Prevention ◽

Prediction Accuracy ◽

Gait Cycle ◽

Objective Measure ◽

Gait Stability ◽

Finite Time Lyapunov Exponent ◽

Falls In Older Adults ◽

Prevention Methods ◽

New Phase ◽

Coordinate Transforms

ABSTRACTIdentification of individuals at risk of falling is important when designing fall prevention methods. Current stability measures that estimate gait stability and robustness appear limited in predicting falls in older adults. Inspired by recent findings of phase-dependent local stability changes within a gait cycle, we used compass-walker models to test several phase-dependent stability metrics for their usefulness to predict gait robustness. These metrics are closely related to the often-employed maximum finite-time Lyapunov exponent and maximum Floquet multiplier. They entail linearizing the system in a rotating hypersurface orthogonal to the period-one solution, and estimating the local divergence rate of the swing phases and the foot strikes. We correlated the metrics with the gait robustness of two compass walker models with either point or circular feet to estimate their prediction accuracy. To also test for the metrics’ invariance under coordinate transform, we represented the point-feet walker in both Euler-Lagrange and Hamiltonian canonical form. Our simulations revealed that for most of the metrics, correlations differ between models and also change under coordinate transforms, severely limiting the prediction accuracy of gait robustness. The only exception that consistently correlated with gait robustness is the divergence of foot strikes. These results admit challenges of using phase-dependent stability metrics as objective measure to quantify gait robustness.

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The Identification and Parameterization of Armax and State Space Forms

Econometrica ◽

10.2307/1913438 ◽

1976 ◽

Vol 44 (4) ◽

pp. 713 ◽

Cited By ~ 92

Author(s):

E. J. Hannan

Keyword(s):

State Space ◽

Space Forms

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State-space forms for higher-order discrete-time models

Systems & Control Letters ◽

10.1016/s0167-6911(97)00132-1 ◽

1998 ◽

Vol 34 (1-2) ◽

pp. 23-31 ◽

Cited By ~ 15

Author(s):

A.Raymond Comeau ◽

Noriyuki Hori

Keyword(s):

State Space ◽

Discrete Time ◽

Higher Order ◽

Space Forms ◽

Discrete Time Models

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The Association between Gait Speed and Falls in Community Dwelling Older Adults with and without Mild Cognitive Impairment

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18073712 ◽

2021 ◽

Vol 18 (7) ◽

pp. 3712

Author(s):

Claire E. Adam ◽

Annette L. Fitzpatrick ◽

Cindy S. Leary ◽

Anjum Hajat ◽

Elizabeth A. Phelan ◽

...

Keyword(s):

Older Adults ◽

Cognitive Impairment ◽

Mild Cognitive Impairment ◽

Gait Speed ◽

Community Dwelling ◽

Self Report ◽

P Value ◽

Risk Of Falling ◽

Falls In Older Adults ◽

Status Interaction

(1) Background: Falls are common in older adults and result in injuries, loss of independence, and death. Slow gait is associated with falls in older adults, but few studies have assessed the association between gait speed and falls among those with mild cognitive impairment (MCI). (2) Methods: The association between gait speed and falls was assessed in 2705 older adults with and without MCI participating in the Ginkgo Evaluation of Memory Study. Gait speed was measured via a 15-foot walk test and fall history through self-report. We used data collected at the 12-month (2001–2003) and 18-month visits (2002–2004). (3) Results: Participant average age was 78.5 years (sd = 3.2); 45% were female, and 14% had MCI at baseline. The average gait speed was 0.93 m/s (sd = 0.20). Sixteen percent (n = 433) and 18% (n = 498) reported at least one fall at the 12-month and 18-month visits, respectively. Faster gait speed was associated with decreased risk of falling (RR: 0.95, 95% CI: 0.91, 0.99) for every 10 cm/s increase in gait speed adjusted for age, gender, study arm, site, and MCI status. (4) Conclusions: The relationship between gait speed and risk of falling did not vary by MCI status (interaction p-value = 0.78).

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Robust op amp circuit realizations using tridiagonal state space forms

48th Midwest Symposium on Circuits and Systems, 2005. ◽

10.1109/mwscas.2005.1594024 ◽

2005 ◽

Author(s):

D. Turer ◽

R. DeCarlo

Keyword(s):

State Space ◽

Space Forms ◽

Op Amp

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Personality and Falls Among Older Adults: Evidence From a Longitudinal Cohort

The Journals of Gerontology Series B ◽

10.1093/geronb/gbz040 ◽

2019 ◽

Vol 75 (9) ◽

pp. 1905-1910 ◽

Cited By ~ 3

Author(s):

Brice Canada ◽

Yannick Stephan ◽

Angelina R Sutin ◽

Antonio Terracciano

Keyword(s):

Older Adults ◽

Personality Traits ◽

Personality Assessment ◽

Cox Regression ◽

Smoking Status ◽

Handgrip Strength ◽

Risk Of Falling ◽

Falls In Older Adults ◽

Demographic Covariates

Abstract Objectives Falls can have catastrophic consequences, especially for older adults. This study examined whether personality traits predict the incidence of falls in older age. Method Participants were older adults aged from 65 to 99 years (N = 4,759) drawn from the Health and Retirement Study. Personality traits and demographic factors were assessed at baseline. Falls were tracked for up to 11 years. Results Over the follow-up period, 2,811 individuals reported falls. Cox regression analyses that included demographic covariates indicated that lower conscientiousness and higher neuroticism increased the risk of falling. Disease burden, depressive symptoms, and physical inactivity mediated the associations between both traits and falls incidence, whereas smoking status and handgrip strength mediated the neuroticism–falls incidence association. Discussion This study provides new prospective evidence that personality predicts the incidence of falls in older adults and suggest that personality assessment may help identifying individuals at higher risk of falling.

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Stability of gait and interlimb coordination in older adults

Journal of Neurophysiology ◽

10.1152/jn.00950.2011 ◽

2012 ◽

Vol 107 (9) ◽

pp. 2560-2569 ◽

Cited By ~ 30

Author(s):

T. Krasovsky ◽

M. C. Baniña ◽

R. Hacmon ◽

A. G. Feldman ◽

A. Lamontagne ◽

...

Keyword(s):

Older Adults ◽

Center Of Mass ◽

Interlimb Coordination ◽

Forward Movement ◽

Gait Stability ◽

High Functioning ◽

Double Support ◽

Falls In Older Adults ◽

Older Subjects

Most falls in older adults occur when walking, specifically following a trip. This study investigated the short- and longer term responses of young ( n = 24, 27.6 ± 4.5 yr) and older adults ( n = 18, 69.1 ± 4.2 yr) to a trip during gait at comfortable speed and the role of interlimb coordination in recovery from tripping. Subjects walked on a self-paced treadmill when forward movement of their dominant leg was unexpectedly arrested for 250 ms. Recovery of center of mass (COM) movements and of double-support duration following perturbation was determined. In addition, the disruption and recovery of interlimb coordination of the arms and legs was evaluated. Although young and older subjects used similar lower limb strategies in response to the trip, older adults had less stable COM movement patterns before perturbation, had longer transient destabilization (>25%) after perturbation, required more gait cycles to recover double-support duration (older, 3.48 ± 0.7 cycles; young, 2.88 ± 0.4 cycles), and had larger phase shifts that persisted after perturbation (older, −83° to −90°; young, −39° to −42°). Older adults also had larger disruptions to interlimb coordination of the arms and legs. The timing of the initial disruption in coordination was correlated with the disturbance in gait stability only in young adults. In older adults, greater initial COM instability was related to greater longer term arm incoordination. These results suggest a relationship between interlimb coordination and gait stability, which may be associated with fall risk in older adults. Reduced coordination and gait stability suggest a need for stability-related functional training even in high-functioning older adults.

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