A New Lower Extremity Modeling of Human Body With Variable Feet Links

2000 ◽  
Author(s):  
Nader Arafati ◽  
Jean Yves Lazennec ◽  
Roger Ohayon
Keyword(s):  
Ground Reaction Force ◽  
Sagittal Plane ◽  
Reaction Force ◽  
Human Movement ◽  
Knee Joints ◽  
Foot Pressure ◽  
Ankle Joints ◽  
Reaction Forces ◽  
Human Movement Modeling ◽  
Force Vectors

Abstract Human movement modeling has been the object of much research for the past 30 years. In these models the position of foot link was fixed on the ground. We propose to model the feet links as variable, since the position of foot pressure center changes from heel to toes. The ground reaction forces could also be analyzed in real time. We examined this model for some static postures. In standing anatomical position, the maximum articular forces are localized in hip and knee joints. In sagittal plane, the ground reaction force vectors are positioned nearly under ankle joints. The pathological postures like body with pes cavus or with global spine kyphosis increase the articular and muscular forces. In these cases, the position of ground reaction force vectors is moved toward the toes.

Does Wearing a Prophylactic Ankle Brace During Drop Landings Affect Lower Extremity Kinematics and Ground Reaction Forces?

2013 ◽  
Vol 29 (2) ◽  
pp. 205-213 ◽  
Author(s):  
Kathy J. Simpson ◽  
Jae P. Yom ◽  
Yang-Chieh Fu ◽  
Scott W. Arnett ◽  
Sean O’Rourke ◽  
...  
Keyword(s):  
Knee Joint ◽  
Lower Extremity ◽  
Ground Reaction Force ◽  
External Rotation ◽  
Reaction Force ◽  
Knee Joints ◽  
Ground Reaction Forces ◽  
Ankle Brace ◽  
Reaction Forces ◽  
Drop Landings

The objective of the study was to determine if prophylactic ankle bracing worn by females during landings produces abnormal lower extremity mechanics. Angular kinematic and ground reaction force (GRF) data were obtained for 16 athletically experienced females who performed brace and no-brace drop landings. The brace condition displayed reduced in/external rotation and flexion displacements about the ankle and knee joints and increased vertical and mediolateral GRF peak magnitudes and rate of vertical GRF application (pairedttest,P< .05). The ankle and knee joints landed in a less plantar flexed and more flexed position, respectively. No significant ab/adduction outcomes may have occurred due to interparticipant variability and/or a lack of brace restriction. Conclusion: During typical landings, this lace-up brace increases vertical GRF, decreases ankle and knee joint displacements of flexion and int/external rotation, but minimally affects ab/adduction displacements.

scholarly journals Running ground reaction forces across footwear conditions are predicted from the motion of two body mass components

2019 ◽  
Vol 126 (5) ◽  
pp. 1315-1325 ◽  
Author(s):  
Andrew B. Udofa ◽  
Kenneth P. Clark ◽  
Laurence J. Ryan ◽  
Peter G. Weyand
Keyword(s):  
Ground Reaction Force ◽  
Lower Limb ◽  
Reaction Force ◽  
Ground Reaction Forces ◽  
Vertical Ground Reaction Force ◽  
Time Patterns ◽  
Foot Strike ◽  
Reaction Forces ◽  
Vertical Ground ◽  
Force Time

Although running shoes alter foot-ground reaction forces, particularly during impact, how they do so is incompletely understood. Here, we hypothesized that footwear effects on running ground reaction force-time patterns can be accurately predicted from the motion of two components of the body’s mass (mb): the contacting lower-limb (m1 = 0.08mb) and the remainder (m2 = 0.92mb). Simultaneous motion and vertical ground reaction force-time data were acquired at 1,000 Hz from eight uninstructed subjects running on a force-instrumented treadmill at 4.0 and 7.0 m/s under four footwear conditions: barefoot, minimal sole, thin sole, and thick sole. Vertical ground reaction force-time patterns were generated from the two-mass model using body mass and footfall-specific measures of contact time, aerial time, and lower-limb impact deceleration. Model force-time patterns generated using the empirical inputs acquired for each footfall matched the measured patterns closely across the four footwear conditions at both protocol speeds ( r2 = 0.96 ± 0.004; root mean squared error  = 0.17 ± 0.01 body-weight units; n = 275 total footfalls). Foot landing angles (θF) were inversely related to footwear thickness; more positive or plantar-flexed landing angles coincided with longer-impact durations and force-time patterns lacking distinct rising-edge force peaks. Our results support three conclusions: 1) running ground reaction force-time patterns across footwear conditions can be accurately predicted using our two-mass, two-impulse model, 2) impact forces, regardless of foot strike mechanics, can be accurately quantified from lower-limb motion and a fixed anatomical mass (0.08mb), and 3) runners maintain similar loading rates (ΔFvertical/Δtime) across footwear conditions by altering foot strike angle to regulate the duration of impact. NEW & NOTEWORTHY Here, we validate a two-mass, two-impulse model of running vertical ground reaction forces across four footwear thickness conditions (barefoot, minimal, thin, thick). Our model allows the impact portion of the impulse to be extracted from measured total ground reaction force-time patterns using motion data from the ankle. The gait adjustments observed across footwear conditions revealed that runners maintained similar loading rates across footwear conditions by altering foot strike angles to regulate the duration of impact.

Ground reaction force and hoof deceleration patterns on two different surfaces at the trot

2006 ◽  
Vol 3 (4) ◽  
pp. 209-216 ◽  
Author(s):  
Pia Gustås ◽  
Christopher Johnston ◽  
Stig Drevemo
Keyword(s):  
Ground Reaction Force ◽  
Reaction Force ◽  
Force Plate ◽  
Ground Surface ◽  
Ground Reaction Forces ◽  
Triaxial Accelerometer ◽  
Loading Rates ◽  
Sand Surface ◽  
Reaction Forces ◽  
Force Data

AbstractThe objective of the present study was to compare the hoof deceleration and ground reaction forces following impact on two different surfaces. Seven unshod Standardbreds were trotted by hand at 3.0–5.7 m s− 1 over a force plate covered by either of the two surfaces, sandpaper or a 1 cm layer of sand. Impact deceleration data were recorded from one triaxial accelerometer mounted on the fore- and hind hooves, respectively. Ground reaction force data were obtained synchronously from a force plate, sampled at 4.8 kHz. The differences between the two surfaces were studied by analysing representative deceleration and force variables for individual horses. The maximum horizontal peak deceleration and the loading rates of the vertical and the horizontal forces were significantly higher on sandpaper compared with the sand surface (P < 0.001). In addition, the initial vertical deceleration was significantly higher on sandpaper in the forelimb (P < 0.001). In conclusion, it was shown that the different qualities of the ground surface result in differences in the hoof-braking pattern, which may be of great importance for the strength of the distal horse limb also at slow speeds.

Correlation between Ground Reaction Force and Tibial Acceleration in Vertical Jumping

2007 ◽  
Vol 23 (3) ◽  
pp. 180-189 ◽  
Author(s):  
Niell G. Elvin ◽  
Alex A. Elvin ◽  
Steven P. Arnoczky
Keyword(s):  
Ground Reaction Force ◽  
Reaction Force ◽  
Force Plate ◽  
Coefficient Of Determination ◽  
Ground Reaction Forces ◽  
Accelerometer Data ◽  
Jump Height ◽  
Vertical Jumping ◽  
Average Coefficient ◽  
Reaction Forces

Modern electronics allow for the unobtrusive measurement of accelerations outside the laboratory using wireless sensor nodes. The ability to accurately measure joint accelerations under unrestricted conditions, and to correlate them with jump height and landing force, could provide important data to better understand joint mechanics subject to real-life conditions. This study investigates the correlation between peak vertical ground reaction forces, as measured by a force plate, and tibial axial accelerations during free vertical jumping. The jump heights calculated from force-plate data and accelerometer measurements are also compared. For six male subjects participating in this study, the average coefficient of determination between peak ground reaction force and peak tibial axial acceleration is found to be 0.81. The coefficient of determination between jump height calculated using force plate and accelerometer data is 0.88. Data show that the landing forces could be as high as 8 body weights of the jumper. The measured peak tibial accelerations ranged up to 42 g. Jump heights calculated from force plate and accelerometer sensors data differed by less than 2.5 cm. It is found that both impact accelerations and landing forces are only weakly correlated with jump height (the average coefficient of determination is 0.12). This study shows that unobtrusive accelerometers can be used to determine the ground reaction forces experienced in a jump landing. Whereas the device also permitted an accurate determination of jump height, there was no correlation between peak ground reaction force and jump height.

Effect of Hopping Frequency on Bilateral Differences in Leg Stiffness

2013 ◽  
Vol 29 (1) ◽  
pp. 55-60 ◽  
Author(s):  
Hiroaki Hobara ◽  
Koh Inoue ◽  
Kazuyuki Kanosue
Keyword(s):  
Ground Reaction Force ◽  
Center Of Mass ◽  
Reaction Force ◽  
Human Movement ◽  
Vertical Ground Reaction Force ◽  
Mass Model ◽  
Lower Extremity Injuries ◽  
Leg Stiffness ◽  
Significant Difference ◽  
Bilateral Differences

Understanding the degree of leg stiffness during human movement would provide important information that may be used for injury prevention. In the current study, we investigated bilateral differences in leg stiffness during one-legged hopping. Ten male participants performed one-legged hopping in place, matching metronome beats at 1.5, 2.2, and 3.0 Hz. Based on a spring-mass model, we calculated leg stiffness, which is defined as the ratio of maximal ground reaction force to maximum center of mass displacement at the middle of the stance phase, measured from vertical ground reaction force. In all hopping frequency settings, there was no significant difference in leg stiffness between legs. Although not statistically significant, asymmetry was the greatest at 1.5 Hz, followed by 2.2 and 3.0 Hz for all dependent variables. Furthermore, the number of subjects with an asymmetry greater than the 10% criterion was larger at 1.5 Hz than those at 2.2 and 3.0 Hz. These results will assist in the formulation of treatment-specific training regimes and rehabilitation programs for lower extremity injuries.

Measurement differences between three versus five photocells during collection of ground reaction forces in dogs

2007 ◽  
Vol 02 (02) ◽  
pp. 98-101 ◽  
Author(s):  
J. P. Punke ◽  
A. L. Speas ◽  
L. R. Reynolds ◽  
C. M. Andrews ◽  
S. C. Budsberg
Keyword(s):  
Ground Reaction Force ◽  
Reaction Force ◽  
False Negative ◽  
False Negative Rate ◽  
Second Phase ◽  
False Negatives ◽  
Two Systems ◽  
Reaction Forces ◽  
Force Data ◽  
Gathering Data

SummaryThe differences between velocities and accelerations obtained from three and five photocells were examined when obtaining ground reaction force (GRF) data in dogs. Ground reaction force data was collected 259 times from 16 different dogs in two experimental phases. The first phase compared velocities and accelerations reported by the two systems based on trials accepted by the three photocell system. The second phase accepted trials based on data from five photocells. Three photocell data were calculated mathematically in the second phase in order to compare the values of both systems. The velocity and acceleration values obtained from each system were significantly different (at the hundredth of a meter per second). Differences in measured values did not result in acceptance of data by the three photocell system that would not have been acceptable with the five photocell system (false positives), but did result in rejection of acceptable data by the three photocell system (11% false negative rate). Given the small differences between the two systems, GRF data collected should not be significantly different, though the three photocell system is less efficient in gathering data due to the number of trials rejected as false negatives.

The evaluation of modified foot orthosis on muscle activity and kinetic in a subject with flexible flat foot : Single case study

2013 ◽  
Vol 38 (2) ◽  
pp. 160-166 ◽  
Author(s):  
Hassan Saeedi ◽  
Mohammad E Mousavi ◽  
Basir Majddoleslam ◽  
Mehdi Rahgozar ◽  
Gholamreza Aminian ◽  
...  
Keyword(s):  
Ground Reaction Force ◽  
Muscle Activity ◽  
Sagittal Plane ◽  
Single Case ◽  
Reaction Force ◽  
Vertical Ground Reaction Force ◽  
Flat Foot ◽  
Case Evaluation ◽  
The University ◽  
Foot Orthosis

Background:Due to blocking of pronation/dorsiflexion in flexible flat foot and restriction of these movements in using the University of California Berkeley Laboratory orthosis, provided pressures in sole by the orthosis were increased. Therefore, this article describes the evaluation of modified foot orthosis with flexible structure in the management of individuals with flexible flat foot.Case description and method:The patient was a 21-year-old male who had symptomatic flat foot. The modified foot orthosis included movable surface and the outside structure. The modified foot orthosis was evaluated by standing foot X-ray, comfort rate, electromyography of leg muscle and vertical ground reaction force during walking.Findings and outcomes:The modified foot orthosis improved the foot alignment and decreased the symptoms of flat foot with more comfort. Subtalar position by sub-maximum supination had higher position than neutral in sagittal plane. It may increase the muscle activity of peroneus longus by 7% compared to barefoot, and there was a decrease of 11% ground reaction force in mid stance.Conclusion:The result of this single case evaluation only proposed the feasibility of this modified insole as the orthotic treatment in flexible flat foot.Clinical relevanceThe modified foot orthosis, which is mobile in the midfoot, is an orthosis for walking and standing in subjects with flexible flat foot.

Ground Reaction Forces in Children’s Gait

1989 ◽  
Vol 1 (1) ◽  
pp. 45-53 ◽  
Author(s):  
Nancy L. Greer ◽  
Joseph Hamill ◽  
Kevin R. Campbell
Keyword(s):  
Sex Differences ◽  
Ground Reaction Force ◽  
Reaction Force ◽  
Ground Reaction Forces ◽  
Vertical Force ◽  
Reaction Forces ◽  
Braking Force ◽  
Force Components ◽  
Age Range ◽  
Minimum Force

Ground reaction force patterns during walking were observed in 18 children 3 and 4 years of age. The children walked barefoot at a self-chosen walking pace. Selected variables representing the vertical, anteroposterior, and mediolateral force components were evaluated. The results indicated that children in this age range contact the ground with greater vertical force measures relative to body mass than do adults. In addition, the minimum vertical force was lower, the transition from braking to propulsion occurred earlier, and the mediolateral force excursions were higher than typically found in adults. When the children were divided into groups on the basis of sex, differences were observed between those groups. The boys exhibited a greater difference in the vertical peak forces, a lower minimum force, a greater braking force, and a higher mediolateral force excursion value. The results indicated that children display a different ground reaction force pattern than do adults and that differences between boys and girls may be observed as early as ages 3 and 4 years.

scholarly journals Pirouette Vertical Ground Reaction Force of Ballet Dancers and Non-Dancers

2020 ◽  
Vol 14 (2) ◽  
pp. 53-61
Author(s):  
Cynthia Hiraga ◽  
Camila Siriani ◽  
Paulo Ricardo Higassiaraguti Rocha ◽  
Débora Alves Souza ◽  
José Angelo Barela
Keyword(s):  
Ground Reaction Force ◽  
Reaction Force ◽  
Vertical Force ◽  
Ballet Dancer ◽  
Vertical Ground Reaction Force ◽  
Ballet Dancers ◽  
Dance Training ◽  
Reaction Forces ◽  
Vertical Ground ◽  
Initial Impulse

BACKGROUND: Different amounts of force are needed to produce an effective turn for the pirouette, especially vertical force. AIM: To examine the vertical force produced by the supporting leg during the execution of a pirouette en dehors of ballet dancer and non-dancer participants. METHOD: The participants included five ballet dancers who composed the ballet dancer group and eight girls without previous experience of dance training who composed the non-dancer group. The participants were invited to execute the pirouette en dehors on a force platform with each leg as the supporting leg. Two-way analyses of variance were used to test vertical reaction forces between the two groups over the preferred and non-preferred leg. RESULTS: Among the three vertical forces measured in the present study, the maximum vertical peak for the initial impulse was significantly higher for the ballet dancers compared to the non-dancer girls. The minimum vertical force and maximum vertical peak for the final impulse were similar between both groups. CONCLUSION: The results suggest that the initial vertical force may be critical to the pirouette en dehors, determining proficient execution of this movement in ballet dancers.

Sign in / Sign up

Export Citation Format

Share Document