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.

IN VITRO SIMULATION OF THE STANCE PHASE IN HUMAN GAIT

2001 ◽  
Vol 05 (02) ◽  
pp. 113-121 ◽  
Author(s):  
Kyu-Jung Kim ◽  
Harold B. Kitaoka ◽  
Zong-Ping Luo ◽  
Satoru Ozeki ◽  
Lawrence J. Berglund ◽  
...  
Keyword(s):  
Stance Phase ◽  
Sagittal Plane ◽  
Center Of Pressure ◽  
Reaction Force ◽  
Human Gait ◽  
Heel Strike ◽  
Foot And Ankle ◽  
Vertical Ground Reaction Force ◽  
Cross Sectional

The purpose of this study is to develop an electromechanical system for dynamic simulation of the stance phase of a human gait using cadaveric foot specimens. The system can be used for quantification of foot and ankle pathomechanics and design of foot and ankle reconstructive surgeries. Servo-pneumatic systems were used for application of the tibial weight loading and muscle loadings. A four-bar mechanism was constructed to provide the progressive motion of a tibia during the simulation while the external loadings were simultaneously applied. Muscle loadings were estimated based on the physiological cross-sectional area and normal electromyography (EMG) data with the assumption of the linear EMG–force relationship. Ad hoc tuning of the unknown muscle gains was conducted until a reasonable match with the normal vertical ground reaction force profile, center of pressure advancement, and characteristic foot motion events (heel strike, foot flat, heel rise and toe-off) could be made. Three cadaver feet and an artificial foot were tested with five repeated trials. The simulator reproduced the stance phase of a human gait in the sagittal plane with reasonable accuracy and consistency without compromising either kinematics or kinetics of the foot and ankle complex.

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 The Effect of Teeth Clenching on Dynamic Balance at Jump-Landing: A Pilot Study

2017 ◽  
Vol 33 (3) ◽  
pp. 211-215
Author(s):  
Tomomasa Nakamura ◽  
Yuriko Yoshida ◽  
Hiroshi Churei ◽  
Junya Aizawa ◽  
Kenji Hirohata ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Masseter Muscle ◽  
Center Of Pressure ◽  
Dynamic Balance ◽  
Reaction Force ◽  
Force Plate ◽  
Vertical Ground Reaction Force ◽  
Jump Landing ◽  
Teeth Clenching ◽  
Vertical Ground

The aim of this study was to analyze the effect of teeth clenching on dynamic balance at jump landing. Twenty-five healthy subjects performed jump-landing tasks with or without teeth clenching. The first 3 trials were performed with no instruction; subsequently, subjects were ordered to clench at the time of landing in the following 3 trials. We collected the data of masseter muscle activity by electromyogram, the maximum vertical ground reaction force (vGRFmax) and center of pressure (CoP) parameters by force plate during jump-landing. According to the clenching status of control jump-landing, all participants were categorized into a spontaneous clenching group and no clenching group, and the CoP data were compared. The masseter muscle activity was correlated with vGRFmax during anterior jump-landing, while it was not correlated with CoP. In comparisons between the spontaneous clenching and the no clenching group during anterior jump-landing, the spontaneous clenching group showed harder landing and the CoP area became larger than the no clenching group. There were no significant differences between pre- and postintervention in both spontaneous clenching and no clenching groups. The effect of teeth clenching on dynamic balance during jump-landing was limited.

scholarly journals Differences in Biomechanical Loading Magnitude During a Landing Task in Male Athletes with and without Patellar Tendinopathy

2021 ◽  
Author(s):  
Laura S. Pietrosimone ◽  
J. Troy Blackburn ◽  
Erik A. Wikstrom ◽  
David J. Berkoff ◽  
Sean I. Docking ◽  
...  
Keyword(s):  
Patellar Tendon ◽  
Stance Phase ◽  
Load Capacity ◽  
Statistical Significance ◽  
Reaction Force ◽  
Patellar Tendinopathy ◽  
Structural Abnormality ◽  
Vertical Ground Reaction Force ◽  
Male Athletes ◽  
Data Points

ABSTRACT Context: Prior research has not established if overloading or underloading movement profiles are present in symptomatic and asymptomatic athletes with patellar tendon structural abnormality (PTA) compared to healthy athletes. Objective: The purpose was to compare involved limb landing biomechanics between male athletes with and without patellar tendinopathy. Design: Cross-sectional study Setting: Laboratory Patients or Other Participants: 43 males were grouped based on patellar tendon pain & ultrasound imaging of the proximal patellar tendon: symptomatic with PTA (SYM-PTA; n=13; 20±2yrs; 1.8±0.1m; 84±5kg), asymptomatic with PTA (ASYM-PTA; n=15; 21±2yrs; 1.8±0.1m; 82±13kg), and healthy control (CON; n=15; 20±2yrs; 1.8±0.1m; 79±12kg). Main Outcome Measures: 3D biomechanics were collected during double-limb jump-landing. Kinematic (knee flexion angle (KF)) and kinetic (vertical ground reaction force (VGRF); internal knee extension moment (KEM); patellar tendon force (FPT)) variables were analyzed as continuous waveforms during the stance phase for the involved limb. Mean values were calculated for each 1% of stance, normalized over 202 data points (0–100%), and plotted with 95% confidence intervals. Statistical significance was defined as a lack of 95% CI overlap for ≥ 6 consecutive data points. Results: SYM-PTA had lesser KF than CON throughout the stance phase. ASYM-PTA had lesser KF than CON in the early and late stance phase. SYM-PTA group had lesser KEM and FPT than CON in early stance, as well as ASYM-PTA in mid-stance. Conclusions: Male athletes with SYM-PTA demonstrated a patellar tendon load-avoidance profile compared to ASYM-PTA and CON athletes. ASYM-PTA did not show evidence of overloading compared to CON. Our findings support the need for individualized treatments for athletes with tendinopathy to maximize load-capacity. Trial Registry: ClinicalTrials.gov (#XXX).

scholarly journals Comparison Between Spatiotemporal Parameters and Vertical Ground Reaction Force in Ankle Sprain Coper and Healthy Athletes: A Cross Sectional Study

2021 ◽  
pp. 111-120
Author(s):  
Zaha Raeisi ◽  
Keyword(s):  
Ankle Sprain ◽  
Stance Phase ◽  
Gait Cycle ◽  
Reaction Force ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Vertical Ground Reaction Force ◽  
Cross Sectional ◽  
Spatiotemporal Parameters ◽  
Vertical Ground

Purpose: It is essential to maintain dynamic stability during walking to perform daily tasks independently. The present study aimed at comparing the spatiotemporal parameters and the values of the vertical Ground Reaction Force (vGRF) as well as determining the time to reach them in ankle-sprain coper and healthy athletes during the stance phase of gait. Methods: A total of 28 female university athletes were recruited in this cross-sectional study and assigned into two groups: ankle-sprain coper (n=14) and healthy control (n=14). The gait cycle analysis was then performed on a 10-m path, and the information related to the stance phase was recorded by a foot scanning device. The spatiotemporal parameters (gait line and contact time) and the values of the vGRF along with the time to reach them were subsequently obtained from each test. The repeated measures Analysis of Variance (ANOVA) was additionally used to analyze the data (P≤0.05). Results: The study results revealed no differences between the injured and the healthy feet in the ankle-sprain coper group in any of the variables (P>0.05). As well, the spatiotemporal gait cycle parameters between the ankle-sprain coper group and the healthy controls were not significantly different (P>0.05). However, significant differences were observed between the ankle-sprain coper and healthy controls in terms of the variables of the vGRF in the mid-stance (F=5.25, P=0.03) and the time to reach the second peak of the vGRF (F=9.13, P=0.006). Conclusion: The spatiotemporal gait parameters were not significantly different between the ankle-sprain coper and the control groups, but the vGRF in the ankle-sprain coper was greater than that in the control group. With regard to the correlation between the reduction in the vGRF and the secondary injury, it is recommended to pay much attention to this point in rehabilitation programs following the first injury in female athletes.

scholarly journals Vertical ground reaction force analysis during gait with unstable shoes

2015 ◽  
Vol 28 (3) ◽  
pp. 459-466
Author(s):  
Giulia Pereira ◽  
Aluísio Otavio Vargas Avila ◽  
Rudnei Palhano
Keyword(s):  
Ground Reaction Force ◽  
Reaction Force ◽  
Force Plate ◽  
Vertical Ground Reaction Force ◽  
Significant Difference ◽  
Vertical Ground ◽  
The Subject ◽  
Unstable Shoes ◽  
The Right ◽  
The Impact

AbstractIntroduction Footwear is no longer just an accessory but also a protection for the musculoskeletal system, and its most important characteristic is comfort.Objectives This study aims to identify and to analyze the vertical ground reaction force in barefoot women and women with unstable shoes.Methodology Five women aged 25 ± 4 years old and mass of 50 ± 7 kg participated in this study. An AMTI force plate was used for data acquisition. The 10 trials for each situation were considered valid where the subject approached the platform with the right foot and at the speed of 4 km/h ± 5%. The instable shoe of this study is used in the practice of physical activity.Results The results showed that the first peak force was higher for the footwear situation, about 5% and significant differences between the barefoot and footwear situation. This significant difference was in the first and second peaks force and in the time of the second peak.Conclusion The values showed that the footwear absorbs approximately 45% of the impact during gait.

Limb Dominance Related to the Variability and Symmetry of the Vertical Ground Reaction Force and Center of Pressure

2012 ◽  
Vol 28 (4) ◽  
pp. 473-478 ◽  
Author(s):  
Yun Wang ◽  
Kazuhiko Watanabe
Keyword(s):  
Ground Reaction Force ◽  
Center Of Pressure ◽  
Reaction Force ◽  
Rehabilitation Program ◽  
Vertical Ground Reaction Force ◽  
Foot Pressure ◽  
Walking Gait ◽  
Posterior Direction ◽  
Vertical Ground ◽  
Limb Dominance

The notion of limb dominance has been commonly used in the upper extremity, yet the two lower extremities are often treated as equal for analytical purposes. Attempts to determine the effects of limb laterality on gait have produced conflicting results. The purpose of this study was to determine if limb dominance affects the vertical ground reaction force and center of pressure (COP) during able-bodied gait. The Parotec system (Paromed GmbH, Germany) was used to collect plantar foot pressure data. Fifteen subjects volunteered to participate in this study. The coefficient of variation of the COP displacement in the mediolateral direction and the variability of peak force beneath the lateral forefoot in the nondominant foot were significant greater than in the dominant foot. Moreover, COP velocity in the anterior-posterior direction during the terminal stance phase showed greater value in the dominant foot. Our study provides support for limb laterality by showing limb dominance affected the vertical ground reaction force and center of pressure during walking gait. This finding suggests it is an important issue in movement science for clinicians and would assist in improving sports performance and rehabilitation program.

scholarly journals Evaluation of a Kinematically-Driven Finite Element Footstrike Model

2016 ◽  
Vol 32 (3) ◽  
pp. 301-305 ◽  
Author(s):  
Iain Hannah ◽  
Andy Harland ◽  
Dan Price ◽  
Heiko Schlarb ◽  
Tim Lucas
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Center Of Pressure ◽  
Reaction Force ◽  
Element Model ◽  
Mechanical Tests ◽  
Vertical Ground Reaction Force ◽  
Dynamic Finite Element ◽  
Tetrahedral Elements ◽  
Vertical Ground

A dynamic finite element model of a shod running footstrike was developed and driven with 6 degree of freedom foot segment kinematics determined from a motion capture running trial. Quadratic tetrahedral elements were used to mesh the footwear components with material models determined from appropriate mechanical tests. Model outputs were compared with experimental high-speed video (HSV) footage, vertical ground reaction force (GRF), and center of pressure (COP) excursion to determine whether such an approach is appropriate for the development of athletic footwear. Although unquantified, good visual agreement to the HSV footage was observed but significant discrepancies were found between the model and experimental GRF and COP readings (9% and 61% of model readings outside of the mean experimental reading ± 2 standard deviations, respectively). Model output was also found to be highly sensitive to input kinematics with a 120% increase in maximum GRF observed when translating the force platform 2 mm vertically. While representing an alternative approach to existing dynamic finite element footstrike models, loading highly representative of an experimental trial was not found to be achievable when employing exclusively kinematic boundary conditions. This significantly limits the usefulness of employing such an approach in the footwear development process.

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.

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