Shoes with active insoles mitigate declines in balance after fatigue

Moon, Jeongin; Pathak, Prabhat; Kim, Sudeok; Roh, Seulki; Roh, Changhyun; Shim, Youngbo; Ahn, Jooeun

doi:10.1038/s41598-020-58815-9

Cited by 17 publications

(16 citation statements)

References 57 publications

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“…where K LQR is the optimal control gain matrix found via the LQR procedure. The matrices Q and R in (5) weight the state and input deviations from zero in the cost function.…”

Section: The Linear Quadratic Regulatormentioning

confidence: 99%

Frequency-Dependent Force Direction Elucidates Neural Control of Balance

Shiozawa

Lee

Russo

et al. 2020

Preprint

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Background: Maintaining upright posture is an unstable task that requires control of translational and rotational motions. Humans use foot-ground interaction force, characterized by point of application, magnitude, and direction to manage body accelerations. Previous work identified a point of intersection of the foot-ground interaction force vectors that exhibited consistent frequency-dependent behavior. Methods: To test whether this frequency-dependent behavior provided a distinctive signature of neural control or was a necessary consequence of biomechanics, this study simulated quiet standing and compared the results with human subject data. If a standing human was modeled as a single inverted pendulum, no controller could reproduce the experimentally observed frequency-dependence of the intersection point height. The simplest competent model that approximated a standing human was a double inverted pendulum with torque-actuated ankle and hip joints. It was stabilized by a linear feedback controller based on position and velocity errors of each joint. Results: When the relative cost between state deviation and control effort was varied, the frequency at which the intersection point crossed the center of mass position shifted. A similar effect was obtained by varying the relative cost between the ankle and hip control effort. The relative strength of ankle and hip actuation noise added to the simulated system affected the intersection point height at high frequencies. Conclusions: As a range of controller parameter sets could stabilize this model and produce the observed change in the vertical position of the intersection point with increasing frequency, the decrease in intersection point height appears to reflect a biomechanical constraint and not a consequence of control. Among the several controller parameter sets considered, that which best reproduced the human experimental results used minimal control effort and more ankle torque than hip torque. This suggests that the neural strategy employed by human subjects to maintain quiet standing balance engages at least two degrees of freedom and is best described by minimal control eort and emphasizing ankle torque.

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“…where K LQR is the optimal control gain matrix found via the LQR procedure. The matrices Q and R in (5) weight the state and input deviations from zero in the cost function.…”

Section: The Linear Quadratic Regulatormentioning

confidence: 99%

Frequency-Dependent Force Direction Elucidates Neural Control of Balance

Shiozawa

Lee

Russo

et al. 2020

Preprint

View full text Add to dashboard Cite

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“…Consistent behavioral patterns observed across subjects, represented by descriptive measures such as center of mass (COM) or center of pressure (COP) motion, suggest strategies to manage complex whole-body balancing in a coordinated manner [8][9][10][12][13][14]. While there is no doubt that characterizing behavioral patterns is important, it does not define the postural control strategy [1].…”

Section: Understanding Natural Balance Without Perturbationsmentioning

confidence: 99%

“…The remaining nonlinearities would either be differentiable or resemble noise, and small motions would justify a linearized representation. Indeed it has been widely reported that unperturbed human balancing exhibits subtle movement [13,27]. The stationarity of human balance is debatable [5,31,32]; due to fatigue or change in control strategy (e.g., transitioning between an 'ankle strategy' and a 'hip strategy' [28]) during balancing, the system may exhibit time-varying dynamics.…”

Section: Linear and Stationary Processesmentioning

confidence: 99%

Identifying Human Postural Dynamics and Control from Unperturbed Balance

Lee

Zhang

Hogan

2020

Preprint

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Backgrounds: Upright standing requires control of an inherently unstable multi-joint human body within a small base of support, despite biological motor and / or sensory noise which challenge balance. Without applying perturbations, system identification methods have been regarded as inadequate, because the relevant internal biological noise processes are not accessible to direct measurement. As a result, unperturbed balance studies have been limited to investigation of subjects' behavioral response patterns rather than possible underlying control strategies. Methods: In this paper, we present a mathemathically rigorous system identification method that is applicable to study the dynamics and control of unperturbed balance. The method is derived from autocorrelation matrices with non-zero time lags and identifies the system matrix of a discrete-time dynamic system in the presence of unknown noise processes, without requiring any information about the strength of the noise. Results: Unlike reasonable `least-squares' approaches, the performance of the new method is consistent across a range of different combinations of internal and measurement noise strengths, even when measurement noise is substantial. We present a numerical example of a model that simulates human upright balancing and show that its dynamics can be identified accurately. With a biomechanically reasonable choice of state and input variables, a state feedback controller can also be identified. Conclusions: Our numerical results indicate that the system identification method proposed in this paper is applicable to real-world experimental data. Using this method, the dynamics and control of human quiet standing can be studied in depth without concern for adaptation or possible reflex responses evoked by external perturbations, or any need for expensive high-precision measurement equipment. This may enable diagnosis and treatment of individual subjects with impaired balance, and the development of safe and effective assistive and / or rehabilitative technologies.

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“…These changes may increase the incidence of sport injuries [24]. To date, most fatigue and footwear studies have predominantly focused on running economy [26], subjective comfort [27] and balance control [28]. However, limited efforts have been exerted on the relationship between footwear cushioning and fatigue in basketball.…”

Section: Introductionmentioning

confidence: 99%

Wearing Cushioning Shoes Reduce Load Rates More Effectively in Post-Fatigue than in Pre-Fatigue during Landings

Wang

Deng

Lam

et al. 2021

Biology

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Purpose: this study aimed to investigate the footwear cushioning effects on impact forces and joint kinematics of the lower extremity during bipedal drop landings before and after acute exercise-induced fatigue protocol. Methods: in this case, 15 male collegiate basketball athletes performed drop landings from a 60 cm platform wearing highly-cushioned shoes (HS) and less cushioned shoes (control shoes, CS) before and after acute fatigue-inducing exercises (i.e., shuttle run combined with multiple vertical jumps). Force plates and motion capturing systems were synchronised to measure ground reaction forces and kinematic data during drop landings. Maximum jump height was analysed with one-way ANOVA. Two-way repeated measure ANOVAs were performed on each of the tested variables to examine if there was significant main effects of shoe and fatigue as well as the interaction. The significance level was set to 0.05. Results: rearfoot peak impact forces and loading rates significantly reduced when the participants wore HS in pre- and post-fatigue conditions. The peak loading rates in forefoot significantly reduced when HS were worn in post-fatigue. Compared with pre-fatigue, wearing HS contributed to with 24% and 13% reduction in forefoot and rearfoot peak loading rates, respectively, and the occurrence times of first and second peak impact forces and loading rates were much later. In the post-fatigue, a significant increase in the initial contact and minimum angles of the ankle were observed in HS compared with CS. Conclusion: these findings suggest that footwear cushioning can reduce landing-related rearfoot impact forces regardless of fatigue conditions. In a situation where the neuromuscular activity is reduced or absent such as post-fatigue wearing better cushioning shoes show superior attenuation, as indicated by lower forefoot and rearfoot impacts.

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Shoes with active insoles mitigate declines in balance after fatigue

Cited by 17 publications

References 57 publications

Frequency-Dependent Force Direction Elucidates Neural Control of Balance

Frequency-Dependent Force Direction Elucidates Neural Control of Balance

Identifying Human Postural Dynamics and Control from Unperturbed Balance

Wearing Cushioning Shoes Reduce Load Rates More Effectively in Post-Fatigue than in Pre-Fatigue during Landings

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