scholarly journals Postural and Trunk Responses to Unexpected Perturbations Depend on the Velocity and Direction of Platform Motion

2016 ◽  
pp. 769-776
Author(s):  
E. ZEMKOVÁ ◽  
Z. KOVÁČIKOVÁ ◽  
M. JELEŇ ◽  
K. NEUMANNOVÁ ◽  
M. JANURA
Keyword(s):  
Center Of Pressure ◽  
Peak Velocity ◽  
Center Of Mass ◽  
Lateral Direction ◽  
Physically Active ◽  
Platform Motion ◽  
Trunk Motion ◽  
Posterior Direction ◽  
Highly Correlated ◽  
Postural Perturbations

This study compares postural and trunk responses to translating platform perturbations of varied velocities and directions. A group of 18 young and physically active subjects were exposed to a set of postural perturbations at varied velocities (5, 10, 15, and 20 cm/s) and directions of platform movement (forward, backward, left-lateral, and right-lateral). The center of pressure (CoP) displacement measurement, in addition to the trunk motion (representing the center of mass (CoM) displacement), were both monitored. Results identified that the CoP displacement increased from slow to faster velocities of platform motion more widely in both anterior and posterior directions (50.4 % and 48.4 %) as compared to the CoM displacement (17.8 % and 14.9 %). However a greater increase in the peak CoM velocity (70.3 % and 69.6 %) and the peak CoM acceleration (60.5 % and 53.1 %) was observed. The values in the anterior and posterior direction only differed significantly at the highest velocity of platform motion (i.e. 20 cm/s). A similar tendency was observed in the medio-lateral direction, but there were no significant differences in any parameter in the left-lateral and right-lateral direction. The velocity of the platform motion highly correlated with peak velocity (r=0.92-0.97, P<0.01) and moderately with amplitude of trunk displacement (r=0.56-0.63, P<0.05). These findings indicate that the velocity of perturbation alters peak CoM velocity rather than the magnitude of CoM displacement. The effect of the direction of perturbations on the trunk response emerges only at a high velocity of platform motion, such that the peak CoM velocity and peak CoM acceleration are significantly greater in anterior than posterior direction.

Hip Sway in Patients With Hip Osteoarthritis During One-Leg Standing With a Focus on Time Series Data

Motor Control ◽  
2021 ◽  
pp. 1-17
Author(s):  
Takuya Ibara ◽  
Makoto Takahashi ◽  
Koichi Shinkoda ◽  
Mahito Kawashima ◽  
Masaya Anan
Keyword(s):  
Time Series ◽  
Center Of Pressure ◽  
Hip Osteoarthritis ◽  
Series Data ◽  
Scaling Exponent ◽  
Balance Performance ◽  
Kinematic Parameters ◽  
Lateral Direction ◽  
Posterior Direction ◽  
Anterior Posterior

This study aimed to investigate the hip sway and the relationship between the center of pressure (CoP) and kinematic parameters regarding the time series scaling component α in patients with hip osteoarthritis (OA) during a one-leg standing task. The scaling exponent α, SD, hip sway maximal acceleration change, and balance performance, which was measured using CoP parameters, were compared between hip OA and control groups during a one-leg standing task. The relationships between balance performance with CoP parameters and kinematic parameters were investigated with the regression analysis. In the hip OA group, the scaling exponent α was smaller in the medial–lateral direction, and the SD and maximal amount of change in hip sway acceleration were larger in the anterior–posterior direction in the hip OA group. In this group, the CoP parameters were significantly associated with α in the medial–lateral direction (negatively) and in the anterior–posterior direction (positively). In the hip OA group, hip sway adaptability in the medial–lateral direction was limited, while the anterior–posterior direction showed greater movement.

A Comprehensive Evaluation of Spine Kinematics, Kinetics, and Trunk Muscle Activities During Fatigue-Induced Repetitive Lifting

2021 ◽  
pp. 001872082098362
Author(s):  
Zeinab Kazemi ◽  
Adel Mazloumi ◽  
Navid Arjmand ◽  
Ahmadreza Keihani ◽  
Zanyar Karimi ◽  
...  
Keyword(s):  
Center Of Pressure ◽  
Comprehensive Evaluation ◽  
Center Of Mass ◽  
Force Plate ◽  
Compressive Force ◽  
Biomechanical Model ◽  
Trunk Muscle ◽  
Abdominal Muscles ◽  
Spine Kinematics ◽  
Posterior Direction

Objective Spine kinematics, kinetics, and trunk muscle activities were evaluated during different stages of a fatigue-induced symmetric lifting task over time. Background Due to neuromuscular adaptations, postural behaviors of workers during lifting tasks are affected by fatigue. Comprehensive aspects of these adaptations remain to be investigated. Method Eighteen volunteers repeatedly lifted a box until perceived exhaustion. Body center of mass (CoM), trunk and box kinematics, and feet center of pressure (CoP) were estimated by a motion capture system and force-plate. Electromyographic (EMG) signals of trunk/abdominal muscles were assessed using linear and nonlinear approaches. The L5-S1 compressive force (Fc) was predicted via a biomechanical model. A two-way multivariate analysis of variance (MANOVA) was performed to examine the effects of five blocks of lifting cycle (C1 to C5) and lifting trial (T1 to T5), as independent variables, on kinematic, kinetic, and EMG-related measures. Results Significant effects of lifting trial blocks were found for CoM and CoP shift in the anterior–posterior direction (respectively p < .001 and p = .014), trunk angle ( p = .004), vertical box displacement ( p < .001), and Fc ( p = .005). EMG parameters indicated muscular fatigue with the extent of changes being muscle-specific. Conclusion Results emphasized variations in most kinematics/kinetics, and EMG-based indices, which further provided insight into the lifting behavior adaptations under dynamic fatiguing conditions. Application Movement and muscle-related variables, to a large extent, determine the magnitude of spinal loading, which is associated with low back pain.

scholarly journals Analysis of Postural Instability in the Upright Position on Narrow Platforms and the Interactions with Postural Constraints

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3909
Author(s):  
Atsushi Sugama ◽  
Akihiko Seo
Keyword(s):  
Postural Balance ◽  
Sagittal Plane ◽  
Center Of Pressure ◽  
Center Of Mass ◽  
Upright Position ◽  
Pendulum Model ◽  
Working Postures ◽  
Loss Of Balance ◽  
Highly Correlated ◽  
Anterior Posterior

Background: Loss of balance is a considerable risk factor for workers while using ladders, because they are required to maintain static postural balance on platforms of a restricted size. This study observed center of mass (CoM) and center of pressure (CoP) behaviors and evaluated the effects of the platform depth (anterior–posterior length) and working postures. Methods: Eleven male participants stood on four platforms with depths ranging from 6 to 15 cm and maintained their positions for 60 s while performing or not performing other tasks (object holding, upward viewing, or both simultaneously). The kinematics were analyzed on the sagittal plane based on the inverse pendulum model. Results: The absolute moving range for the CoP–CoM linearly increased with the decreasing platform depth, and the working postures affected the slopes of the linear fits. The relative range of CoP–CoM displacement on narrow platforms was highly correlated with the subjective sense of instability. Conclusions: Monitoring the CoP is effective for a better understanding and evaluation of static postural balance. This study’s findings contribute to improving the design of work equipment through the use of wider platforms that are robust against the effects of working postures.

Strategies for maintaining dynamic balance in persons with neurological disorders during overground walking

2021 ◽  
pp. 095441192110236
Author(s):  
Tiziana Lencioni ◽  
Denise Anastasi ◽  
Ilaria Carpinella ◽  
Anna Castagna ◽  
Alessandro Crippa ◽  
...  
Keyword(s):  
Neurological Disorder ◽  
Center Of Pressure ◽  
Balance Control ◽  
Dynamic Balance ◽  
Objective Assessment ◽  
Center Of Mass ◽  
Frontal Plane ◽  
Rehabilitation Program ◽  
Lower Limbs ◽  
Lateral Direction

Maintaining a stable gait requires a dynamic balance control, that can be altered in persons with Multiple Sclerosis (MS), Stroke (ST), and Parkinson’s disease (PD). The understanding of the strategy for Center of Mass (CoM) positioning adopted by patients during walking is important to be able to program treatments aimed at improving gait control and preventing falls. Forty-four persons with a mild-to-moderate neurological disorder (20 with MS, 14 with ST, 10 with PD) underwent clinical examination and gait analysis. Ten Healthy Subjects (HS) walking at matched speed provided the normative data. Dynamic balance was assessed using the margin of stability (MoS). It was calculated as the distance between the extrapolated Center of Pressure and the extrapolated CoM at mid-stance. The MoS values for lower limbs were calculated in patients and compared with speed-matched values of HS. Persons with neurological disorder showed increased MoS in the medio-lateral direction with respect to HS. Within-group comparison analysis showed a symmetry between lower limbs in HS (Mean (95%CI) [mm], dominant vs non-dominant limb, 43.3 (31.9–54.6) vs 42.9 (28.8–56.9)) and PD (less affected vs more affected limb, 71.1 (59.8–82.5) vs 72.5 (58.5–86.6)), while a significant asymmetry was found in MS (54.4 (46.4–62.4) vs 81.1 (71.2–91.1)) and ST (52.1 (42.6–61.7) vs 74.7 (62.8–86.6)) participants. The history of falls was comparable among PD, MS, and ST groups, and the MoS in the frontal plane showed a strong correlation with these records. Objective assessment of MoS revealed pathology-specific strategies showing different impacts in MS, ST, and PD on the ability to control CoM information to manage the balance between limbs during gait. MoS evaluation will provide useful information to address a tailored rehabilitation program and to monitor disease progression.

scholarly journals Postural Preparation to Stepping: Coupled Center of Pressure Shifts in the Anterior-Posterior and Medio-Lateral Directions

2016 ◽  
Vol 54 (1) ◽  
pp. 5-14 ◽  
Author(s):  
Clint Hansen ◽  
Jacques LaRue ◽  
Manh-Cuong Do ◽  
Mark L. Latash
Keyword(s):  
Center Of Pressure ◽  
Initial Conditions ◽  
Force Plate ◽  
Single Step ◽  
The Body ◽  
Lateral Direction ◽  
Postural Adjustments ◽  
Neural Organization ◽  
Posterior Direction ◽  
Anterior Posterior

AbstractWe explored changes in the postural preparation to stepping introduced by modifications of the initial coordinates of the center of pressure (COP). We hypothesized that the postural adjustments in the anterior-posterior direction would persist across all initial COP manipulations while the adjustments in the medio-lateral direction would be highly sensitive to the initial COP coordinate. Healthy subjects stood on a force plate, shifted the body weight to one of the initial conditions that spanned the range of COP coordinates in both directions, and initiated a single step or started to walk. No major changes were observed between the stepping and walking conditions. Changes in the initial COP coordinate in the medio-lateral direction led to scaling of the magnitude of the COP shift in that direction prior to stepping accompanied by a nearly proportional change in the COP shift in the anterior-posterior direction. Changes in the initial COP coordinate in the anterior-posterior direction led to scaling of the magnitude of the COP shift in that direction prior to stepping without consistent changes in the COP shift in the medio-lateral direction. We interpret the results as reflecting a neural organization using a small set of referent body configurations for the postural adjustments.

scholarly journals Transfer and generalization of learned manipulation between unimanual and bimanual tasks

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Trevor Lee-Miller ◽  
Marco Santello ◽  
Andrew M. Gordon
Keyword(s):  
Learning Transfer ◽  
Center Of Pressure ◽  
Center Of Mass ◽  
Pressure Point ◽  
Torque Generation ◽  
Before And After ◽  
Object Center ◽  
High Level ◽  
Bimanual Grasping ◽  
Partial Learning

AbstractSuccessful object manipulation, such as preventing object roll, relies on the modulation of forces and centers of pressure (point of application of digits on each grasp surface) prior to lift onset to generate a compensatory torque. Whether or not generalization of learned manipulation can occur after adding or removing effectors is not known. We examined this by recruiting participants to perform lifts in unimanual and bimanual grasps and analyzed results before and after transfer. Our results show partial generalization of learned manipulation occurred when switching from a (1) unimanual to bimanual grasp regardless of object center of mass, and (2) bimanual to unimanual grasp when the center of mass was on the thumb side. Partial generalization was driven by the modulation of effectors’ center of pressure, in the appropriate direction but of insufficient magnitude, while load forces did not contribute to torque generation after transfer. In addition, we show that the combination of effector forces and centers of pressure in the generation of compensatory torque differ between unimanual and bimanual grasping. These findings highlight that (1) high-level representations of learned manipulation enable only partial learning transfer when adding or removing effectors, and (2) such partial generalization is mainly driven by modulation of effectors’ center of pressure.

Letter to the editor regarding “The assessment of center of mass and center of pressure during quiet stance: Current applications and future directions”

2021 ◽  
Vol 128 ◽  
pp. 110729
Author(s):  
Peter Federolf ◽  
Rosa M Angulo-Barroso ◽  
Albert Busquets ◽  
Blai Ferrer-Uris ◽  
Øyvind Gløersen ◽  
...  
Keyword(s):  
Center Of Pressure ◽  
Center Of Mass ◽  
Quiet Stance ◽  
Future Directions ◽  
Letter To The Editor

scholarly journals Can Muscle Stiffness Alone Stabilize Upright Standing?

1999 ◽  
Vol 82 (3) ◽  
pp. 1622-1626 ◽  
Author(s):  
Pietro G. Morasso ◽  
Marco Schieppati
Keyword(s):  
Center Of Pressure ◽  
Center Of Mass ◽  
Muscle Stiffness ◽  
The Body ◽  
Ankle Muscles ◽  
Upright Standing ◽  
Stiffness Control ◽  
Control Patterns ◽  
Physiological Values

A stiffness control model for the stabilization of sway has been proposed recently. This paper discusses two inadequacies of the model: modeling and empiric consistency. First, we show that the in-phase relation between the trajectories of the center of pressure and the center of mass is determined by physics, not by control patterns. Second, we show that physiological values of stiffness of the ankle muscles are insufficient to stabilize the body “inverted pendulum.” The evidence of active mechanisms of sway stabilization is reviewed, pointing out the potentially crucial role of foot skin and muscle receptors.

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