scholarly journals Adaptation to Coriolis force perturbations of postural sway requires an asymmetric two-leg model

2019 ◽  
Vol 121 (6) ◽  
pp. 2042-2060 ◽  
Author(s):  
Avijit Bakshi ◽  
Paul DiZio ◽  
James R. Lackner
Keyword(s):  
Coriolis Force ◽  
Postural Sway ◽  
Balance Control ◽  
Force Plate ◽  
Companion Paper ◽  
Two Dimensions ◽  
Body Sway ◽  
Coriolis Forces ◽  
Movement Trajectories ◽  
Parameterized Model

In the companion paper (Bakshi A, DiZio P, Lackner JR. J Neurophysiol. In press, 2019), we reported how voluntary forward-backward sway in a rotating room generated medial-lateral Coriolis forces that initially deviated intended body sway paths. Pure fore-aft sway was gradually restored over per-rotation trials, and a negative aftereffect occurred during postrotation sway. Force plate recordings showed that subjects learned to compensate for the Coriolis forces by executing a bimodal torque, the distribution of which was asymmetric across the two legs and of opposite sign for forward vs. backward sway. To explain these results, we have developed an asymmetric, nonparallel-leg, inverted pendulum model to characterize upright balance control in two dimensions. Fore-aft and medial-lateral sway amplitudes can be biomechanically coupled or independent. Biomechanical coupling occurs when Coriolis forces orthogonal to the direction of movement perturb sway about the ankles. The model includes a mechanism for alternating engagement/disengagement of each leg and for asymmetric drive to the ankles to achieve adaptation to Coriolis force-induced two-dimensional sway. The model predicts the adaptive control underlying the adaptation of voluntary postural sway to Coriolis forces. A stability analysis of the model generates parameter values that match those measured experimentally, and the parameterized model simulations reproduce the experimentally observed sway trajectories. NEW & NOTEWORTHY This paper presents a novel nonparallel leg model of postural control that correctly predicts the perturbations of voluntary sway that occur in a rotating environment and the adaptive changes that occur to restore faithful movement trajectories. This engaged leg model (ELM) predicts the asymmetries in force distribution and their patterns between the two legs to restore accurate movement trajectories. ELM has clinical relevance for pathologies that generate postural asymmetries and for altered gravitoinertial force conditions.

scholarly journals Rapid adaptation to Coriolis force perturbations of voluntary body sway

2019 ◽  
Vol 121 (6) ◽  
pp. 2028-2041 ◽  
Author(s):  
Avijit Bakshi ◽  
Paul DiZio ◽  
James R. Lackner
Keyword(s):  
Postural Control ◽  
Coriolis Force ◽  
Sagittal Plane ◽  
Postural Sway ◽  
Force Plate ◽  
Arm Movement ◽  
Mirror Image ◽  
Body Sway ◽  
Coriolis Forces ◽  
Voluntary Sway

Studying adaptation to Coriolis perturbations of arm movements has advanced our understanding of motor control and learning. We have now applied this paradigm to two-dimensional postural sway. We measured how subjects ( n = 8) standing at the center of a fully enclosed rotating room who made voluntary anterior-posterior swaying movements adapted to the Coriolis perturbations generated by their sway. Subjects underwent four voluntary sway trials prerotation, 20 per-rotation at 10 rpm counterclockwise, and 10 postrotation. Each trial lasted 20 s, and subjects were permitted normal vision. Their voluntary sway during rotation generated Coriolis forces that initially induced rightward deviations of their forward sway paths and leftward deviations of their backward sway. Sagittal plane sway was gradually restored over per-rotation trials, and a mirror image aftereffect occurred in postrotation trials. Dual force plate data analysis showed that subjects learned to counter the Coriolis accelerations during rotation by executing a bimodal torque pattern that was asymmetric across legs and contingent on forward vs. backward movement. The experience-dependent acquisition and washout of this compensation indicate that an internal, feedforward model underlies the leg-asymmetric bimodal torque compensation, contingent on forward vs. backward movement. The learned torque asymmetry we observed for forward vs. backward sway is not consistent with parallel two-leg models of postural control. NEW & NOTEWORTHY This paper describes adaptation to Coriolis force perturbations of voluntary sway in a rotating environment. During counterclockwise rotation, sway paths are deviated clockwise, but full restoration of fore-aft sway is regained in minutes. Negative aftereffects are briefly present postrotation. Current parallel leg models of postural control cannot account for these findings, which show that postural control, like arm movement control, can adapt rapidly and completely to the Coriolis forces generated in artificial gravity environments.

scholarly journals Postural Control in Children With Developmental Coordination Disorder

2005 ◽  
Vol 12 (2-3) ◽  
pp. 183-196 ◽  
Author(s):  
Reint H. Geuze
Keyword(s):  
Motor Development ◽  
Developmental Coordination Disorder ◽  
Postural Sway ◽  
Balance Control ◽  
Age Groups ◽  
Force Plate ◽  
Static Balance ◽  
Motor Tests ◽  
Coordination Disorder ◽  
Balance Problems

The development of static balance is a basic characteristic of normal motor development. Most developmental motor tests include a measure of static balance. Children with Developmental Coordination Disorder (DCD) often fail this item. This study reviews the balance problems of children with DCD. The general conclusion is drawn that under normal conditions static balance control is not a problem for children with DCD. Only in difficult, unattended, or novel situations such children seem to suffer from increased postural sway. These findings raise the question of what happens when balance is lost. The present study addresses the strength of correlation between the electromyography (EMG) and force plate signals in one-leg stance over epochs of stable and unstable balance. Four groups of children were involved in the study: two age groups and a group of children with DCD and balance problems and their controls. The results show a clear involvement of tibialis anterior and peroneus muscles in the control of lateral balance in all conditions and groups. The group of children with DCD and balance problems,however, showed a weaker coupling between EMG and corrective force compared with control children, indicating non-optimal balance control. An evaluation of the existing data in terms of evidence of specific structural deficits associated with DCD provided converging evidence that suggests cerebellar involvement.

scholarly journals Postural control in top-level female volleyball players

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Dorota Borzucka ◽  
Krzysztof Kręcisz ◽  
Zbigniew Rektor ◽  
Michał Kuczyński
Keyword(s):  
Postural Control ◽  
Postural Sway ◽  
Center Of Pressure ◽  
Balance Control ◽  
Sampling Rate ◽  
Force Plate ◽  
Peak Frequency ◽  
Control Group ◽  
Mean Velocity ◽  
Volleyball Players

Abstract Background The aim of this study was to compare the postural control of the Poland national women’s volleyball team players with a control group of non-training young women. It was hypothesized that volleyball players use a specific balance control strategy due to the high motor requirements of their team sport. Methods Static postural sway variables were measured in 31 athletes and 31 non-training women. Participants were standing on a force plate with eyes open, and their center of pressure signals were recorded for the 20s with the sampling rate of 20 Hz in the medial-lateral (ML) and anterior-posterior (AP) planes. Results In both AP and ML planes, athletes had lower range and higher fractal dimension of the COP. They had also higher peak frequency than control group in the ML plane only. The remaining COP indices including variability, mean velocity and mean frequency did not display any intergroup differences. Conclusion It can be assumed that due to the high motor requirements of their sport discipline Polish female volleyball players have developed a unique posture control. On the court they have to distribute their sensory resources optimally between balance control and actions resulting from the specifics of the volleyball game. There are no clearly defined criteria for optimal postural strategies for elite athletes, but they rather vary depending on a given sport. The results of our research confirm this claim. Trial registration The tests were previously approved by the Bioethical Commission of the Chamber of Physicians in Opole. (Resolution No. 151/13.12.2007). This study adheres to the CONSORT guidelines.

Rapid adaptation to Coriolis force perturbations of arm trajectory

1994 ◽  
Vol 72 (1) ◽  
pp. 299-313 ◽  
Author(s):  
J. R. Lackner ◽  
P. Dizio
Keyword(s):  
Coriolis Force ◽  
Opposite Sign ◽  
Tactile Feedback ◽  
Reaching Movements ◽  
Movement Trajectory ◽  
Body Rotation ◽  
Experimental Conditions ◽  
Coriolis Forces ◽  
Partial Restoration ◽  
Movement Trajectories

1. Forward reaching movements made during body rotation generate tangential Coriolis forces that are proportional to the cross product of the angular velocity of rotation and the linear velocity of the arm. Coriolis forces are inertial forces that do not involve mechanical contact. Virtually no constant centrifugal forces will be present in the background when motion of the arm generates transient Coriolis forces if the radius of body rotation is small. 2. We measured the trajectories of arm movements made in darkness to a visual target that was extinguished as movement began. The reaching movements were made prerotation, during rotation at 10 rpm in a fully enclosed rotating room, and postrotation. During testing the subject was seated at the center of the room and pointed radially. Neither visual nor tactile feedback about movement accuracy was present. 3. In experiment 1, subjects reached at a fast or slow rate and their hands made contact with a horizontal surface at the end of the reach. Their initial perrotary movements were highly significantly deviated relative to prerotation in both trajectories and end-points in the direction of the transient Coriolis forces that had been generated during the reaches. Despite the absence of visual and tactile feedback about reaching accuracy, all subjects rapidly regained straight movement trajectories and accurate endpoints. Postrotation, transient errors of opposite sign were present for both trajectories and endpoints. 4. In a second experiment the conditions were identical except that subjects pointed just above the location of the extinguished target so that no surface contact was involved. All subjects showed significant initial perrotation deviations of trajectories and endpoints in the direction of the transient Coriolis forces. With repeated reaches the trajectories, as viewed from above, again became straight, but there was only partial restoration of endpoint accuracy, so that subjects reached in a straight line to the wrong place. Aftereffects of opposite sign were transiently present in the postrotary movements. 5. These observations fail to support current equilibrium point models, both alpha and lambda, of movement control. Such theories would not predict endpoint errors under our experimental conditions, in which the Coriolis force is absent at the beginning and end of a movement. Our results indicate that detailed aspects of movement trajectory are being continuously monitored on the basis of proprioceptive feedback in relation to motor commands. Adaptive compensations can be initiated after one perturbation despite the absence of either visual or tactile feedback about movement trajectory and endpoint error. Moreover, movement trajectory and end-point can be remapped independently.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Mental body rotation with egocentric and object-based transformations in different postures: standing vs. balancing

2021 ◽  
Vol 15 (3) ◽  
pp. 180-194
Author(s):  
Kirsten Budde ◽  
Thomas Jöllenbeck ◽  
José A. Barela ◽  
Gabriella A. Figueiredo ◽  
Matthias Weigelt
Keyword(s):  
Dynamic Stability ◽  
Postural Sway ◽  
Center Of Pressure ◽  
Force Plate ◽  
Body Sway ◽  
Body Rotation ◽  
Balance Beam ◽  
Visual Spatial ◽  
Object Based ◽  
Effects Of Rotation

BACKGROUND: Previous studies suggest better visual-spatial processing when participants are tested in postures in which dynamic stability is challenged. The question arises if this is also true for the performance in mental body-rotation tasks (MBRT). AIM: Taking the embodied cognition approach into account, the first aim of the present study was to examine the potential influence of different demands on dynamic stability for two postures (parallel stand vs. tandem stand) on solving two versions of the MBRT, inducing either an object-based or an egocentric perspective transformation strategy. The second aim was to investigate if these different demands on dynamic stability are reflected in postural sway parameters. METHOD: Thirty participants (18 females and 12 males) were tested in the two MBRTs and in a control condition. All tasks were performed while standing on a balance beam in tandem stand and in a feet parallel position on a force plate. RESULTS: The results for response time and response error revealed effects of rotation angle and task, but no effect of posture. The analyzed Center of Pressure (CoP) data revealed a reduction of body sway during the MBRT for egocentric perspective transformations. CONCLUSION: The results indicate that participants performed better for egocentric than for object-based transformations and that the egocentric transformation leads to more postural stability than the object-based.

scholarly journals Adaptation to Coriolis perturbations of voluntary body sway transfers to preprogrammed fall-recovery behavior

2014 ◽  
Vol 111 (5) ◽  
pp. 977-983 ◽  
Author(s):  
Avijit Bakshi ◽  
Joel Ventura ◽  
Paul DiZio ◽  
James R. Lackner
Keyword(s):  
Postural Sway ◽  
Body Sway ◽  
Forward Motion ◽  
Coriolis Forces ◽  
Adaptation Mechanisms ◽  
Before And After ◽  
Postural Correction ◽  
Fall Recovery ◽  
Voluntary Sway ◽  
Postural Recovery

In a rotating environment, goal-oriented voluntary movements are initially disrupted in trajectory and endpoint, due to movement-contingent Coriolis forces, but accuracy is regained with additional movements. We studied whether adaptation acquired in a voluntary, goal-oriented postural swaying task performed during constant-velocity counterclockwise rotation (10 RPM) carries over to recovery from falling induced using a hold and release (H&R) paradigm. In H&R, standing subjects actively resist a force applied to their chest, which when suddenly released results in a forward fall and activation of an automatic postural correction. We tested H&R postural recovery in subjects ( n = 11) before and after they made voluntary fore-aft swaying movements during 20 trials of 25 s each, in a counterclockwise rotating room. Their voluntary sway about their ankles generated Coriolis forces that initially induced clockwise deviations of the intended body sway paths, but fore-aft sway was gradually restored over successive per-rotation trials, and a counterclockwise aftereffect occurred during postrotation attempts to sway fore-aft. In H&R trials, we examined the initial 10- to 150-ms periods of movement after release from the hold force, when voluntary corrections of movement path are not possible. Prerotation subjects fell directly forward, whereas postrotation their forward motion was deviated significantly counterclockwise. The postrotation deviations were in a direction consistent with an aftereffect reflecting persistence of a compensation acquired per-rotation for voluntary swaying movements. These findings show that control and adaptation mechanisms adjusting voluntary postural sway to the demands of a new force environment also influence the automatic recovery of posture.

scholarly journals Sport-Specific Habitual Adaptations in Neck Kinesthetic Functions Are Related to Balance Controlling Mechanisms

2020 ◽  
Vol 10 (24) ◽  
pp. 8965
Author(s):  
Ziva Majcen Rosker ◽  
Miha Vodicar
Keyword(s):  
Cervical Spine ◽  
Balance Control ◽  
Pearson Correlation ◽  
Force Plate ◽  
Torsion Balance ◽  
Body Sway ◽  
Balance Performance ◽  
Balance Test ◽  
Spine Function ◽  
Neck Torsion

Whilst the importance of trunk, lower and upper extremities for the efficiency of maintaining body sway is well documented, the effects of cervical spine function have been seldom investigated. Afferent information from high density proprioceptors located in the cervical spine can alter postural balance, however the effects of sport’s specific habitual adaptation on balance performance have not yet been investigated. Twenty-seven taekwondo fighters and thirty controls performed unilateral balance tasks while facing forward and during neck torsion balance test while standing on the force plate. Neck kinesthesia was measured with the Head-to-Neutral Relocation test and the Butterfly test with motion-inertial unit. Differences between balance tasks were analyzed using two-way ANOVA. Additionally, correlations between body sway parameters and neck kinesthesia were studied using Pearson correlation coefficient. No differences were found between forward facing and neck torsion balance tasks in taekwondo fighters. However, correlations were found between balance on the non-preferred leg and neck kinesthesia. On the contrary, healthy individuals presented with statistically significant differences between both balance tasks and correlations between balance and neck kinesthesia. Taekwondo fighters seem to present with habitual adaptations in balance control, that differ from non-trained individuals.

Controlling Numerical Dispersion by Variably Timed Flux Updating in Two Dimensions

1982 ◽  
Vol 22 (03) ◽  
pp. 409-419 ◽  
Author(s):  
R.G. Larson
Keyword(s):  
Finite Difference ◽  
Pressure Gradient ◽  
Single Point ◽  
Companion Paper ◽  
Two Dimensions ◽  
Independent Component ◽  
Numerical Dispersion ◽  
Coarse Mesh ◽  
Fixed Concentration ◽  
Order Of Magnitude

Abstract The variably-timed flux updating (VTU) finite difference technique is extended to two dimensions. VTU simulations of miscible floods on a repeated five-spot pattern are compared with exact solutions and with solutions obtained by front tracking. It is found that for neutral and favorable mobility ratios. VTU gives accurate results even on a coarse mesh and reduces numerical dispersion by a factor of 10 or more over the level generated by conventional single-point (SP) upstream weighting. For highly unfavorable mobility ratios, VTU reduces numerical dispersion. but on a coarse mesh the simulation is nevertheless inaccurate because of the inherent inadequacy of the finite-difference estimation of the flow field. Introduction A companion paper (see Pages 399-408) introduced the one-dimensional version of VTU for controlling numerical dispersion in finite-difference simulation of displacements in porous media. For linear and nonlinear, one- and two-independent-component problems, VTU resulted in more than an order-of-magnitude reduction in numerical dispersion over conventional explicit. SP upstream-weighted simulations with the same number of gridblocks. In this paper, the technique is extended to two dimensional (2D) problems, which require solution of a set of coupled partial differential equations that express conservation of material components-i.e., (1) and (2) Fi, the fractional flux of component i, is a function of the set of s - 1 independent-component fractional concentrations {Ci}, which prevail at the given position and time., the dispersion flux, is given by an expression that is linear in the specie concentration gradients. The velocity, is proportional to the pressure gradient,. (3) where lambda, in general, can be a function of composition and of the magnitude of the pressure gradient. The premises on which Eqs. 1 through 3 rest are stated in the companion paper. VTU in Two Dimensions The basic idea of variably-timed flux updating is to use finite-difference discretization of time and space, but to update the flux of a component not every timestep, but with a frequency determined by the corresponding concentration velocity -i.e., the velocity of propagation of fixed concentration of that component. The concentration velocity is a function of time and position. In the formulation described here, the convected flux is upstream-weighted, and all variables except pressure are evaluated explicitly. As described in the companion paper (SPE 8027), the crux of the method is the estimation of the number of timesteps required for a fixed concentration to traverse from an inflow to an outflow face of a gridblock. This task is simpler in one dimension, where there is only one inflow and one outflow face per gridblock, than it is in two dimensions, where each gridblock has in general multiple inflow and outflow faces. SPEJ P. 409^

Postural sway with earth-fixed and body-referenced finger contact in young and older adults

1999 ◽  
Vol 9 (2) ◽  
pp. 103-109
Author(s):  
Reginald L. Reginella ◽  
Mark S. Redfern ◽  
Joseph M. Furman
Keyword(s):  
Older Adults ◽  
Postural Sway ◽  
Center Of Pressure ◽  
Sensory Information ◽  
Body Sway ◽  
Support Surface ◽  
Proprioceptive Information ◽  
Postural Control System ◽  
Fixed Reference ◽  
Older Subjects

Sensory information from lightly touching a reference with the hand is known to influence postural sway in young adults. The primary aim of this study was to compare the influence of finger contact (FC) with an earth-fixed reference to the influence of FC with a body-fixed reference. A second goal of this study was to determine if FC is used differently by older adults compared to younger adults. Using a force plate, center of pressure at the feet was recorded from blindfolded young and older subjects during several conditions. Subjects either did or did not lightly touch a force-sensitive plate that was either earth-fixed or moved forward and backward in synchrony with body sway (that is, sway-referenced). In addition, support surface conditions were also varied, including a fixed floor and a sway-referenced floor using an EquitestTM. Results showed that the type of FC, floor condition, and age each had an effect on postural sway. Touching an earth-fixed plate decreased postural sway as compared to no touching, while touching a sway-referenced plate incresased sway. This influence of FC was enhanced when the floor was sway-referenced. Although older subjects swayed more than young subjects overall, no age-FC interactions occurred, indicating that FC was not utilized differently between the age groups. This study suggests that FC cannot be disregarded as erroneous, especially when proprioceptive information from the legs is distorted. Further, FC is integrated with other sensory information by the postural control system similarly in young and older persons.

Dynamic and Static Assessment of Single-Leg Postural Control in Female Soccer Players

2020 ◽  
Vol 29 (2) ◽  
pp. 174-178
Author(s):  
Kelly M. Meiners ◽  
Janice K. Loudon
Keyword(s):  
Lower Extremity ◽  
Postural Stability ◽  
Postural Sway ◽  
Center Of Pressure ◽  
Force Plate ◽  
Soccer Players ◽  
Balance Test ◽  
Left Lower Extremity ◽  
Static Assessment ◽  
Dynamic Postural Stability

Purpose/Background: Various methods are available for assessment of static and dynamic postural stability. The primary purpose of this study was to investigate the relationship between dynamic postural stability as measured by the Star Excursion Balance Test (SEBT) and static postural sway assessment as measured by the TechnoBody™ Pro-Kin in female soccer players. A secondary purpose was to determine side-to-side symmetry in this cohort. Methods: A total of 18 female soccer players completed testing on the SEBT and Technobody™ Pro-Kin balance device. Outcome measures were anterior, posterior medial, and posterior lateral reaches from the SEBT and center of pressure in the x- and y-axes as well as SD of movement in the forward/backward and medial/lateral directions from the force plate on left and right legs. Bivariate correlations were determined between the 8 measures. In addition, paired Wilcoxon signed-rank tests were performed to determine similarity between limb scores. Results: All measures on both the SEBT and postural sway assessment were significantly correlated when comparing dominant with nondominant lower-extremities with the exception of SD of movement in both x- and y-axes. When correlating results of the SEBT with postural sway assessment, a significant correlation was found between the SEBT right lower-extremity posterior lateral reach (r = .567, P < .05) and summed SEBT (r = .486, P < .05) and the center of pressure in the y-axis. A significant correlation was also found on the left lower-extremity, with SD of forward/backward movement and SEBT posterior medial reach (r = −.511, P < .05). Conclusions: Dynamic postural tests and static postural tests provide different information to the overall assessment of balance in female soccer players. Relationship between variables differed based on the subject’s lower-extremity dominance.

Sign in / Sign up

Export Citation Format

Share Document