Adaptive Changes in Anticipatory Postural Adjustments With Novel and Familiar Postural Supports

Anticipatory postural adjustments (APAs) serve to stabilize posture prior to initiation of voluntary movement. This study examined the effects of changes in postural support on APAs using novel and familiar support paradigms. We also investigated whether postural strategies were refined with practice and how the CNS responded when multiple supports were available. Twelve healthy subjects stood on dual force platforms and performed 20 randomized left and right rapid leg-lift tasks in response to a visual cue under four conditions: unsupported, bilateral handgrip, bite plate, and a combined handgrip and bite plate condition. Vertical ground reaction forces, electromyography of limb, trunk and jaw muscles, and forces exerted on the support apparatus were recorded. Shift in center-of-pressure amplitude and duration were reduced with increased support. Muscles were recruited in advance of the focal movement when able to contribute to stability, and activity was modulated based on the amount of support available. The CNS adapted anticipatory postural strategies immediately with changes in condition regardless of familiarity with the support; however, adaptation was only complete at the first repetition in conditions that involved familiar support strategies. Tasks that involved a novel bite strategy continued to adapt with practice. In the multiple support condition, both hand and bite strategies were immediately incorporated; however, the contribution of each was not identical to conditions where supports were provided individually. This study emphasizes the flexibility of the CNS to organize postural strategies to meet the demands of postural stability in both familiar and novel situations.

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External Forces during Actual Acceleration across Transition Speed

Journal of Applied Biomechanics ◽

10.1123/jab.24.4.340 ◽

2008 ◽

Vol 24 (4) ◽

pp. 340-350 ◽

Cited By ~ 4

Author(s):

Veerle Segers ◽

Peter Aerts ◽

Matthieu Lenoir ◽

Dirk De Clercq

Keyword(s):

Center Of Pressure ◽

Transition Process ◽

Adaptation Period ◽

Transition Speed ◽

Reaction Forces ◽

One Step ◽

Vertical Ground ◽

External Forces ◽

Vertical Ground Reaction Forces ◽

Kinetics Of

The purpose of this study was to examine the kinetics of the walk-to-run transition (WRT) and run-to-walk transition (RWT), when accelerating or decelerating across transition speed (a = 0.17 m·s−2). Nine women performed gait transitions on a 50-m-long walkway. Vertical ground reaction forces (GRFs) and the center of pressure (COP) were examined in the range from 3 steps before to 3 steps after transition in order to identify the possible occurrence of a transition process, in order to facilitate the actual realization of transition. The actual transition is realized in one step, during WRT and RWT. This transition step was characterized by an outlying vertical GRF and COP trajectory (deviating from walking and running). Despite this clear discontinuity, a transitional adaptation period (process) appeared in both transitions. In the WRT, transition was prepared and kinetic adaptations were found in the last step before transition. The RWT was pre- and “post”-pared and only completed during the first walking step after transition. Thus, the WRT and RWT are two distinct phenomena, with different kinetics.

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Use of an instrument sandwiched between the hoof and shoe to measure vertical ground reaction forces and three-dimensional acceleration at the walk, trot, and canter in horses

American Journal of Veterinary Research ◽

10.2460/ajvr.2000.61.979 ◽

2000 ◽

Vol 61 (8) ◽

pp. 979-985 ◽

Cited By ~ 29

Author(s):

Makoto Kai ◽

Osamu Aoki ◽

Atsushi Hiraga ◽

Hironori Oki ◽

Mikihiko Tokuriki

Keyword(s):

Three Dimensional ◽

Ground Reaction Forces ◽

Reaction Forces ◽

Vertical Ground ◽

Vertical Ground Reaction Forces

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Joint angle estimation with wavelet neural networks

Scientific Reports ◽

10.1038/s41598-021-89580-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Saaveethya Sivakumar ◽

Alpha Agape Gopalai ◽

King Hann Lim ◽

Darwin Gouwanda ◽

Sunita Chauhan

Keyword(s):

Gait Analysis ◽

Real Time ◽

Monitoring Applications ◽

Reaction Forces ◽

Multiple Sensor ◽

Vertical Ground ◽

Overall Performance ◽

Gait Monitoring ◽

Vertical Ground Reaction Forces ◽

And Control

AbstractThis paper presents a wavelet neural network (WNN) based method to reduce reliance on wearable kinematic sensors in gait analysis. Wearable kinematic sensors hinder real-time outdoor gait monitoring applications due to drawbacks caused by multiple sensor placements and sensor offset errors. The proposed WNN method uses vertical Ground Reaction Forces (vGRFs) measured from foot kinetic sensors as inputs to estimate ankle, knee, and hip joint angles. Salient vGRF inputs are extracted from primary gait event intervals. These selected gait inputs facilitate future integration with smart insoles for real-time outdoor gait studies. The proposed concept potentially reduces the number of body-mounted kinematics sensors used in gait analysis applications, hence leading to a simplified sensor placement and control circuitry without deteriorating the overall performance.

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Hindlimb muscular activity, kinetics and kinematics of cats jumping to their maximum achievable heights

Journal of Experimental Biology ◽

10.1242/jeb.91.1.73 ◽

1981 ◽

Vol 91 (1) ◽

pp. 73-86 ◽

Cited By ~ 1

Author(s):

F. E. Zajac ◽

M. R. Zomlefer ◽

W. S. Levine

Keyword(s):

Vertical Jump ◽

Muscular Activity ◽

Dynamic State ◽

Extensor Muscles ◽

Ankle Joints ◽

Flexor Muscles ◽

Reaction Forces ◽

Vertical Ground ◽

Vertical Ground Reaction Forces ◽

Propulsion Phase

Cats were trained to jump from a force platform to their maximum achievable heights. Vertical ground reaction forces developed by individual hindlimbs showed that the propulsion phase consists of two epochs. During the initial “preparatory phase' the cat can traverse many different paths. Irrespective of the path traversed, however, the cat always attains the same position, velocity and momentum at the end of this phase. Starting from this dynamic state the cat during the subsequent “launching phase' (about 150 ms long) generates significant propulsion as its hindlimbs develop force with identical, stereotypic profiles. Cinematographic data, electromyographic data, and computed torques about the hip, knee and ankle joints indicate that during the jump proximal extensor musculature is activated before distal musculature. During terminal experiments when the hindlimb was set at positions corresponding to those in the jump, isometric torques produced by tetanic stimulation of groups of extensor and flexor muscles were compared with computed torques developed by the same cat during previous jumps. These comparisons suggest that extensor muscles of the hindlimb are fully activated during the maximal vertical jump.

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Hip and Knee Kinematics and Kinetics During Landing Tasks After Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-Analysis

Journal of Athletic Training ◽

10.4085/1062-6050-334-16 ◽

2018 ◽

Vol 53 (2) ◽

pp. 144-159 ◽

Cited By ~ 12

Author(s):

Adam S. Lepley ◽

Christopher M. Kuenze

Keyword(s):

Ligament Reconstruction ◽

Cruciate Ligament ◽

Meta Analysis ◽

Knee Extension ◽

Injured Limb ◽

Reaction Forces ◽

Vertical Ground ◽

Anterior Cruciate ◽

Vertical Ground Reaction Forces ◽

Kinematics And Kinetics

Objective: To evaluate the current evidence concerning kinematic and kinetic strategies adopted during dynamic landing tasks by patients with anterior cruciate ligament reconstruction (ACLR). Data Sources: PubMed, Web of Science. Study Selection: Original research articles that evaluated kinematics or kinetics (or both) during a landing task in those with a history of ACLR were included. Data Extraction: Methodologic quality was assessed using the modified Downs and Black checklist. Means and standard deviations for knee or hip (or both) kinematics and kinetics were used to calculate Cohen d effect sizes and corresponding 95% confidence intervals between the injured limb of ACLR participants and contralateral or healthy matched limbs. Data were further stratified by landing tasks, either double- or single-limb landing. A random-effects–model meta-analysis was used to calculate pooled effect sizes and 95% confidence intervals. Data Synthesis: The involved limbs of ACLR patients demonstrated clinically and significantly lower knee-extension moments during double-legged landing compared with healthy contralateral limbs and healthy control limbs (Cohen d range = −0.81 to −1.23) and decreased vertical ground reaction forces when compared with healthy controls, regardless of task (Cohen d range = −0.39 to −1.75). Conclusions: During single- and double-legged landing tasks, individuals with ACLR demonstrated meaningful reductions in injured-limb knee-extension moments and vertical ground reaction forces. These findings indicate potential unloading of the injured limb after ACLR, which may have significant implications for secondary ACL injury and long-term joint health.

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