scholarly journals Dynamic Balancing Responses in Unilateral Transtibial Amputees Following Outward-Directed Perturbations During Slow Treadmill Walking Differ Considerably for Amputated and Non-Amputated Side

2021 ◽  
Author(s):  
Andrej Olenšek ◽  
Matjaž Zadravec ◽  
Helena Burger ◽  
Zlatko Matjačić
Keyword(s):  
Stance Phase ◽  
Center Of Pressure ◽  
Center Of Mass ◽  
Reaction Force ◽  
Dynamic Balancing ◽  
Transtibial Amputation ◽  
Control Subjects ◽  
Foot Strike ◽  
Transtibial Amputees ◽  
Proprioceptive Function

Abstract BackgroundDue to disrupted motor and proprioceptive function lower limb amputation imposes considerable challenges associated with balance and greatly increases risk of falling in case of perturbations during walking. The aim of this study was to investigate dynamic balancing responses in unilateral transtibial amputees when they were subjected to perturbing pushes to the pelvis in outward direction at the time of foot strike on non-amputated and amputated side during slow walking.MethodsFourteen subjects with unilateral transtibial amputation and nine control subjects participated in the study. They were subjected to perturbations that were delivered to the pelvis at the time of foot strike of either the left or right leg. We recorded trajectories of center of pressure and center of mass, durations of in-stance and stepping periods as well as ground reaction forces. Statistical analysis was performed to determine significant differences in dynamic balancing responses between control subjects and subjects with amputation when subjected to outward-directed perturbation upon entering stance phases with non-amputated or amputated side.ResultsWhen outward-directed perturbations were delivered at the time of foot strike of the non-amputated leg, subjects with amputation were able to modulate center of pressure and ground reaction force similarly as control subjects which indicates application of in-stance balancing strategies. On the other hand, there was a complete lack of in-stance response when perturbations were delivered when the amputated leg entered the stance phase. Subjects with amputations instead used the stepping strategy and adjusted placement of the non-amputated leg in the ensuing stance phase to make a cross-step. Such response resulted in significantly higher displacement of center of mass. ConclusionsResults of this study suggest that due to the absence of the COP modulation mechanism, which is normally supplied by ankle motor function, people with unilateral transtibial amputation are compelled to choose the stepping strategy over in-stance strategy when they are subjected to outward-directed perturbation on the amputated side. However, the stepping response is less efficient than in-stance response. To improve their balancing responses to unexpected balance perturbation people fitted with passive transtibial prostheses should undergo perturbation-based balance training during clinical rehabilitation.

scholarly journals Dynamic balancing responses in unilateral transtibial amputees following outward-directed perturbations during slow treadmill walking differ considerably for amputated and non-amputated side

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Andrej Olenšek ◽  
Matjaž Zadravec ◽  
Helena Burger ◽  
Zlatko Matjačić
Keyword(s):  
Stance Phase ◽  
Center Of Pressure ◽  
Center Of Mass ◽  
Reaction Force ◽  
Dynamic Balancing ◽  
Transtibial Amputation ◽  
Control Subjects ◽  
Foot Strike ◽  
Transtibial Amputees ◽  
Proprioceptive Function

Abstract Background Due to disrupted motor and proprioceptive function, lower limb amputation imposes considerable challenges associated with balance and greatly increases risk of falling in presence of perturbations during walking. The aim of this study was to investigate dynamic balancing responses in unilateral transtibial amputees when they were subjected to perturbing pushes to the pelvis in outward direction at the time of foot strike on their non-amputated and amputated side during slow walking. Methods Fourteen subjects with unilateral transtibial amputation and nine control subjects participated in the study. They were subjected to perturbations that were delivered to the pelvis at the time of foot strike of either the left or right leg. We recorded trajectories of center of pressure and center of mass, durations of in-stance and stepping periods as well as ground reaction forces. Statistical analysis was performed to determine significant differences in dynamic balancing responses between control subjects and subjects with amputation when subjected to outward-directed perturbation upon entering stance phases on their non-amputated or amputated sides. Results When outward-directed perturbations were delivered at the time of foot strike of the non-amputated leg, subjects with amputation were able to modulate center of pressure and ground reaction force similarly as control subjects which indicates application of in-stance balancing strategies. On the other hand, there was a complete lack of in-stance response when perturbations were delivered when the amputated leg entered the stance phase. Subjects with amputations instead used the stepping strategy and adjusted placement of the non-amputated leg in the ensuing stance phase to make a cross-step. Such response resulted in significantly larger displacement of center of mass. Conclusions Results of this study suggest that due to the absence of the COP modulation mechanism, which is normally supplied by ankle motor function, people with unilateral transtibial amputation are compelled to choose the stepping strategy over in-stance strategy when they are subjected to outward-directed perturbation on the amputated side. However, the stepping response is less efficient than in-stance response.

scholarly journals Dynamic Balancing Responses in Unilateral Transtibial Amputees Following Transversal Plane Perturbations During Slow Treadmill Walking Differ Considerably for Amputated and Nonamputated Side

2020 ◽  
Author(s):  
Andrej Olenšek ◽  
Matjaž Zadravec ◽  
Helena Burger ◽  
Zlatko Matjačić
Keyword(s):  
Healthy Subjects ◽  
Stance Phase ◽  
Centre Of Mass ◽  
Centre Of Pressure ◽  
Dynamic Balancing ◽  
Transtibial Amputation ◽  
Foot Strike ◽  
Transtibial Amputees ◽  
Proprioceptive Function ◽  
Stepping Response

Abstract BackgroundDue to disrupted motor and proprioceptive function lower limb amputation imposes considerable challenges associated with balance and greatly increases risk of falling in case of perturbations during walking. The aim of this study was to investigate dynamic balancing responses in unilateral transtibial amputees when they were subjected to perturbing pushes to the pelvis at the time of foot strike on nonamputated and amputated side during slow walking.MethodsFourteen subjects with unilateral transtibial amputation and nine healthy subjects participated in the study. They were subjected to perturbations that were delivered to the pelvis in different directions at the time of foot strike of either left or right leg. Centre of pressure and centre of mass positions, duration of in-stance and stepping periods as well as ground reaction forces were recorded and analysed for significant differences in dynamic balancing responses between healthy subjects and subjects with amputation when subjected to perturbation upon entering stance phases with nonamputated or amputated side.ResultsWhen perturbations were delivered at the time of foot strike of nonamputated leg subjects with amputation were able to modulate centre of pressure and ground reaction force similarly as healthy subjects. There was a complete lack of in-stance response when perturbations were delivered at the time of foot strike of amputated leg. Instead they used stepping strategy and adjusted placement of nonamputated leg in the ensuing stance phase to increase (forward perturbation) or decrease (backward perturbation) step length or making a cross-step (outward perturbation) which resulted in higher displacement of centre of mass. However, when perturbations were directed inward healthy subjects and subjects with amputation reacted primarily with a stepping response regardless whether healthy, nonamputated or amputated leg was in stance phase.ConclusionsResults of this study suggest that due to the absence of COP modulation mechanism that is normally supplied by calf muscles people with unilateral transtibial amputation are compelled to choose stepping strategy over in-stance strategy when they are subjected to perturbation on the amputated side. However the stepping response is less efficient than in-stance response which may potentially be significant contributor to frequent falls.

scholarly journals Active foot placement control ensures stable gait: Effect of constraints on foot placement and ankle moments

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0242215
Author(s):  
A. M. van Leeuwen ◽  
J. H. van Dieën ◽  
A. Daffertshofer ◽  
S. M. Bruijn
Keyword(s):  
Steady State ◽  
Center Of Pressure ◽  
Center Of Mass ◽  
Reaction Force ◽  
Stride Frequency ◽  
Tight Control ◽  
Foot Placement ◽  
Ankle Moment ◽  
Reaction Forces ◽  
Moment Control

Step-by-step foot placement control, relative to the center of mass (CoM) kinematic state, is generally considered a dominant mechanism for maintenance of gait stability. By adequate (mediolateral) positioning of the center of pressure with respect to the CoM, the ground reaction force generates a moment that prevents falling. In healthy individuals, foot placement is complemented mainly by ankle moment control ensuring stability. To evaluate possible compensatory relationships between step-by-step foot placement and complementary ankle moments, we investigated the degree of (active) foot placement control during steady-state walking, and under either foot placement-, or ankle moment constraints. Thirty healthy participants walked on a treadmill, while full-body kinematics, ground reaction forces and EMG activities were recorded. As a replication of earlier findings, we first showed step-by-step foot placement is associated with preceding CoM state and hip ab-/adductor activity during steady-state walking. Tight control of foot placement appears to be important at normal walking speed because there was a limited change in the degree of foot placement control despite the presence of a foot placement constraint. At slow speed, the degree of foot placement control decreased substantially, suggesting that tight control of foot placement is less essential when walking slowly. Step-by-step foot placement control was not tightened to compensate for constrained ankle moments. Instead compensation was achieved through increases in step width and stride frequency.

A Comparison of Computation Methods for Leg Stiffness During Hopping

2014 ◽  
Vol 30 (1) ◽  
pp. 154-159 ◽  
Author(s):  
Hiroaki Hobara ◽  
Koh Inoue ◽  
Yoshiyuki Kobayashi ◽  
Toru Ogata
Keyword(s):  
Ground Reaction Force ◽  
Stance Phase ◽  
Center Of Mass ◽  
Reaction Force ◽  
Sine Wave ◽  
Phase Method ◽  
Leg Stiffness ◽  
Mass Displacement ◽  
Male Subjects ◽  
Oscillation Method

Despite the presence of several different calculations of leg stiffness during hopping, little is known about how the methodologies produce differences in the leg stiffness. The purpose of this study was to directly compareKlegduring hopping as calculated from three previously published computation methods. Ten male subjects hopped in place on two legs, at four frequencies (2.2, 2.6, 3.0, and 3.4 Hz). In this article, leg stiffness was calculated from the natural frequency of oscillation (method A), the ratio of maximal ground reaction force (GRF) to peak center of mass displacement at the middle of the stance phase (method B), and an approximation based on sine-wave GRF modeling (method C). We found that leg stiffness in all methods increased with an increase in hopping frequency, butKlegvalues using methods A and B were significantly higher than when using method C at all hopping frequencies. Therefore, care should be taken when comparing leg stiffness obtained by method C with those calculated by other methods.

scholarly journals An explorative investigation of functional differences in plantar center of pressure of four foot types using sample entropy method

2016 ◽  
Vol 55 (4) ◽  
pp. 537-548 ◽  
Author(s):  
Zhanyong Mei ◽  
Kamen Ivanov ◽  
Guoru Zhao ◽  
Huihui Li ◽  
Lei Wang
Keyword(s):  
Hallux Valgus ◽  
Stance Phase ◽  
Center Of Pressure ◽  
Reaction Force ◽  
Sample Entropy ◽  
Entropy Method ◽  
Vertical Ground Reaction Force ◽  
Measured Variable ◽  
Pes Cavus ◽  
The Right

Abstract In the study of biomechanics of different foot types, temporal or spatial parameters derived from plantar pressure are often used. However, there is no comparative study of complexity and regularity of the center of pressure (CoP) during the stance phase among pes valgus, pes cavus, hallux valgus and normal foot. We aim to analyze whether CoP sample entropy characteristics differ among these four foot types. In our experiment participated 40 subjects with normal feet, 40 with pes cavus, 19 with pes valgus and 36 with hallux valgus. A Footscan® system was used to collect CoP data. We used sample entropy to quantify several parameters of the investigated four foot types. These are the displacement in medial–lateral (M/L) and anterior–posterior (A/P) directions, as well as the vertical ground reaction force of CoP during the stance phase. To fully examine the potential of the sample entropy method for quantification of CoP components, we provide results for two cases: calculating the sample entropy of normalized CoP components, as well as calculating it using the raw data of CoP components. We also explored what are the optimal values of parameters m (the matching length) and r (the tolerance range) when calculating the sample entropy of CoP data obtained during the stance phases. According to statistical results, some factors significantly influenced the sample entropy of CoP components. The sample entropies of non-normalized A/P values for the left foot, as well as for the right foot, were different between the normal foot and pes valgus, and between the normal foot and hallux valgus. The sample entropy of normalized M/L displacement of the right foot was different between the normal foot and pes cavus. The measured variable for A/P and M/L displacements could serve for the study of foot function.

scholarly journals Active foot placement control ensures stable gait: Effect of constraints on foot placement and ankle moments

2020 ◽  
Author(s):  
A.M. van Leeuwen ◽  
J.H. van Dieën ◽  
A. Daffertshofer ◽  
S.M. Bruijn
Keyword(s):  
Steady State ◽  
Center Of Pressure ◽  
Center Of Mass ◽  
Reaction Force ◽  
Stride Frequency ◽  
Tight Control ◽  
Foot Placement ◽  
Ankle Moment ◽  
Reaction Forces ◽  
Moment Control

AbstractStep-by-step foot placement control, relative to the center of mass (CoM) kinematic state, is generally considered a dominant mechanism for maintenance of gait stability. By adequate (mediolateral) positioning of the center of pressure with respect to the CoM, the ground reaction force generates a moment that prevents falling. In healthy individuals, foot placement is complemented mainly by ankle moment control ensuring stability. To evaluate possible compensatory relationships between step-by-step foot placement and complementary ankle moments, we investigated the degree of (active) foot placement control during steady-state walking, and under either foot placement-, or ankle moment constraints. Thirty healthy participants walked on a treadmill, while full-body kinematics, ground reaction forces and EMG activities were recorded. As a replication of earlier findings, we first showed step-by-step foot placement is associated with preceding CoM state and hip ab-/adductor activity during steady-state walking. Tight control of foot placement appears to be important at normal walking speed because there was a limited change in the degree of foot placement control despite the presence of a foot placement constraint. At slow speed, the degree of foot placement control decreased substantially, suggesting that tight control of foot placement is less essential when walking slowly. Step-by-step foot placement control was not tightened to compensate for constrained ankle moments. Instead compensation was achieved through increases in step width and stride frequency.

POSTURE CONTROL AND BALANCE DURING TAI CHI CHUAN PUSH HANDS MOVEMENTS IN A FIXED STANCE

2012 ◽  
Vol 12 (05) ◽  
pp. 1250030 ◽  
Author(s):  
LIN-HWA WANG ◽  
KUO-CHENG LO ◽  
FONG-CHIN SU
Keyword(s):  
Tai Chi ◽  
Center Of Pressure ◽  
Center Of Mass ◽  
Reaction Force ◽  
Whole Body ◽  
Expert Group ◽  
Tai Chi Chuan ◽  
Kinematic Data ◽  
Analysis System ◽  
Force Data

The present study investigated the adequacy of the interaction between the center of mass (COM) and the center of pressure (COP) for maintaining dynamic stability during Tai Chi Chuan (TCC) Push Hands movements in a fixed stance. The COM of the whole body and COP were calculated. Four TCC experts, with 10.3 ± 1.7 years' experience in the Push Hands technique, and 4 TCC beginners, with 2.5 ± 1.3 years' Push Hands experience, were recruited. An Expert Vision Eagle motion analysis system collected kinematic data and 4 Kistler force plates collected the ground reaction force data. The expert group of TCC practitioners showed a significantly more vertical (P = 0.001) direction in the neutralizing circle, and significantly larger values for anterior–posterior (A–P) (P = 0.006) and vertical (P = 0.0004) displacement in the enticing circle, than the beginner group. Compared with the beginner group, the expert group demonstrated significantly greater velocity A–P (P = 0.001) and vertical (P = 0.001) COM displacements in the enticing circle. A significant extent main effect (P = 0.0028) was observed for the COPA–P excursion between the expert and beginner groups during Push Hands movements. The greater A–P force generated by both groups during the initiation of the Push Hands cycle probably reflects the more rapid and forward-oriented nature of this movement. The TCC beginners might have difficulties with movement transfers because of disruptions in the temporal sequencing of the forces. Overall, results indicated that the initial experience-related differences in COM transfers are reflected in the Push Hands movement cycle.

scholarly journals Ankle muscles activate: mediolateral center of pressure control ensures stable gait

2021 ◽  
Author(s):  
Anina Moira van Leeuwen ◽  
Jaap H van Dieen ◽  
Andreas Daffertshofer ◽  
Sjoerd M Bruijn
Keyword(s):  
Steady State ◽  
Center Of Pressure ◽  
Center Of Mass ◽  
Reaction Force ◽  
Negative Relationship ◽  
Pressure Control ◽  
Foot Placement ◽  
Ankle Moment ◽  
Ankle Muscle ◽  
Moment Control

During steady-state walking mediolateral gait stability can be maintained by controlling the center of pressure (CoP). The CoP modulates the moment of the ground reaction force, which brakes and reverses movement of the center of mass (CoM) towards the lateral border of the base of support. In addition to foot placement, ankle moments serve to control the CoP. We hypothesized that, during steady-state walking, single stance ankle moments establish a CoP shift to correct for errors in foot placement. We expected ankle muscle activity to be associated with this complementary CoP shift. During treadmill walking, full-body kinematics, ground reaction forces and electromyography were recorded in thirty healthy participants. We found a negative relationship between preceding foot placement error and CoP displacement during single stance. Too medial steps were compensated for by a lateral CoP shift and vice versa, too lateral steps were compensated for by a medial CoP shift. Peroneus longus, soleus and tibialis anterior activity correlated with these CoP shifts. As such, we identified an (active) ankle strategy during steady-state walking. As expected, absolute explained CoP variance by foot placement error decreased when walking with shoes constraining ankle moments. Yet, contrary to our expectations that ankle moment control would compensate for constrained foot placement, the absolute explained CoP variance by foot placement error did not increase when foot placement was constrained. We argue that this lack of compensation reflects the interdependent nature of ankle moment and foot placement control. We suggest that single stance ankle moments do not only compensate for preceding foot placement errors, but also assist control of the subsequent foot placement. Foot placement and ankle moment control are caught in a circular relationship, in which constraints imposed on one will also influence the other.

Stepping to an Auditory Metronome Improves Weight-Bearing Symmetry in Poststroke Hemiparesis

2018 ◽  
Vol 34 (6) ◽  
pp. 469-473
Author(s):  
Rachel L. Wright ◽  
Joseph W. Bevins ◽  
David Pratt ◽  
Catherine M. Sackley ◽  
Alan M. Wing
Keyword(s):  
Center Of Pressure ◽  
Weight Bearing ◽  
Center Of Mass ◽  
Reaction Force ◽  
Vertical Component ◽  
Community Dwelling ◽  
Temporal Asymmetry ◽  
Auditory Cue ◽  
Auditory Cueing ◽  
Stepping In Place

Asymmetry in weight-bearing is a common feature in poststroke hemiparesis and is related to temporal asymmetry during walking. The aim of this study was to investigate the effect of an auditory cue for stepping in place on measures of temporal and weight-bearing asymmetry. A total of 10 community-dwelling adults (6 males and 4 females) with chronic poststroke hemiparesis performed 5 un-cued stepping trials and 5 stepping trials cued by an auditory metronome cue. A Vicon system was used to collect full body kinematic trajectories. Two force platforms were used to measure ground reaction forces. Step, swing, and stance times were used to calculate temporal symmetry ratios. Weight-bearing was assessed using the vertical component of the ground reaction force and center of mass–center of pressure separation at mid-stance. Weight-bearing asymmetry was significantly reduced during stepping with an auditory cue. Asymmetry values for step, swing, and stance times were also significantly reduced with auditory cueing. These findings show that auditory cueing when stepping in place produces immediate reductions in measures of temporal asymmetry and dynamic weight-bearing asymmetry.

Ratio of Shear to Load Ground-Reaction Force May Underlie the Directional Tuning of the Automatic Postural Response to Rotation and Translation

2004 ◽  
Vol 92 (2) ◽  
pp. 808-823 ◽  
Author(s):  
Lena H. Ting ◽  
Jane M. Macpherson
Keyword(s):  
Ground Reaction Force ◽  
Center Of Pressure ◽  
Full Range ◽  
Center Of Mass ◽  
Reaction Force ◽  
Postural Response ◽  
Directional Tuning ◽  
Automatic Postural Response ◽  
Consistent Feature ◽  
Perturbation Direction

This study sought to identify the sensory signals that encode perturbation direction rapidly enough to shape the directional tuning of the automatic postural response. We compared reactions to 16 directions of pitch and roll rotation and 16 directions of linear translation in the horizontal plane in freely standing cats. Rotations and translations that displaced the center of mass in the same direction relative to the feet evoked similar patterns of muscle activity and active ground-reaction force, suggesting the presence of a single, robust postural strategy for stabilizing the center of mass in both rotation and translation. Therefore we postulated there should be a common sensory input that encodes the direction of the perturbation and leads to the directional tuning of the early electromyographic burst in the postural response. We compared the mechanical changes induced by rotations and translations prior to the active, postural response. The only consistent feature common to the full range of rotation and translation directions was the initial change in ground-reaction force angle. Other variables including joint angles, ground-reaction force magnitudes, center of pressure, and center of mass in space showed opposite or nonsignificant changes for rotation and translation. Change in force angle at the paw reflects the ratio of loading force to slip force, analogous to slips during finger grip tasks. We propose that cutaneous sensors in the foot soles detect change in ground-reaction force angle and provide the critical input underlying the directional tuning of the automatic postural response for balance.

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