Decomposition of superimposed ground reaction forces into left and right force profiles

AbstractThe purpose of this study was to evaluate 3 different starting techniques from the staggered stance with regards to sprint time, reaction time, linear impulse and power. 11 male amateur American football players volunteered to participate in a testing session consisting of twelve 5 m sprints, 4 in each technique (normal (NORM), backwards false step (BFS) and forwards false step (FFS)) in random order. Sprint starts were performed on force plates to investigate ground reaction forces, reaction time and total sprint time. Analysis showed significant differences in sprint times, with NORM (1.77±0.10 s) being faster than FFS (1.81±0.12 s) and BFS (2.01±0.13 s), and FFS being faster than BFS, although no differences were found in reaction time. In terms of mean force and power, NORM (331.1±39.2N, 542.2±72.3W) and FFS (320.8±43.2N, 550.9±81.4W) were significantly larger than BFS (256.9±36.2N, 443.5±61.1W). This indicates that when starting from a staggered stance, the BFS is inferior to the others and should be avoided. However, since the force profiles of the NORM and the FFS were similar, the differences in sprint time could arise from a technique bias towards the NORM start.

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Estimation of Tri-Axial Walking Ground Reaction Forces of Left and Right Foot from Total Forces in Real-Life Environments

Sensors ◽

10.3390/s18061966 ◽

2018 ◽

Vol 18 (6) ◽

pp. 1966 ◽

Cited By ~ 2

Author(s):

Erfan Shahabpoor ◽

Aleksandar Pavic

Keyword(s):

Real Life ◽

Ground Reaction Forces ◽

Reaction Forces ◽

Left And Right

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Asymmetries in Ground Reaction Forces During Turns by Elite Slalom Alpine Skiers Are Not Related to Asymmetries in Muscular Strength

Frontiers in Physiology ◽

10.3389/fphys.2021.577698 ◽

2021 ◽

Vol 12 ◽

Author(s):

Jan Ogrin ◽

Nejc Šarabon ◽

Mads Kjær Madsen ◽

Uwe Kersting ◽

Hans-Christer Holmberg ◽

...

Keyword(s):

Muscular Strength ◽

Satellite System ◽

The Body ◽

Ground Reaction Forces ◽

Alpine Skiing ◽

Reaction Forces ◽

Left And Right ◽

Alpine Skiers ◽

Global Navigation Satellite ◽

Right Turns

The ground reaction forces (GRF) associated with competitive alpine skiing, which are relatively large, might be asymmetric during left and right turns due to asymmetries in the strength of the legs and torso and the present investigation was designed to evaluate this possibility. While skiing a symmetrical, 20-gate slalom course, the asymmetries of 9 elite alpine skiers were calculated on the basis of measurements provided by inertial motion units (IMU), a Global Navigation Satellite System and pressure insoles. In addition, specialized dynamometers were utilized to assess potential asymmetry in the strength of their legs and torso in the laboratory. In total, seven variables related to GRF were assessed on-snow and eight related to strength of the legs and torso in the laboratory. The asymmetries in these parameters between left and right turns on snow were expressed in terms of the symmetry (SI) and Jaccard indices (JI), while the asymmetries between the left and right sides of the body in the case of the laboratory measurements were expressed as the SIs. The three hypotheses to be tested were examined using multivariable regression models. Our findings resulted in rejection of all three hypotheses: The asymmetries in total GRF (H1), as well as in the GRF acting on the inside and outside legs (H2) and on the rear- and forefeet GRF (H3) during left and right turns were not associated with asymmetries in parameters related to muscular strength. Nevertheless, this group of elite slalom skiers exhibited significant asymmetry between their right and left legs with respect to MVC during ankle flexion (0.53 ± 0.06 versus 0.60 ± 0.07 Nm/kg, respectively) and hip extension (2.68 ± 0.39 versus 2.17 ± 0.26 Nm/kg), as well as with respect to the GRFs on the inside leg while skiing (66.8 ± 7.39 versus 76.0 ± 10.0 %BW). As indicated by the JI values, there were also large asymmetries related to GRF as measured by pressure insoles (range: 42.7–56.0%). In conclusion, inter-limb asymmetries in GRFs during elite alpine skiing are not related to corresponding asymmetries in muscular strength. Although our elite athletes exhibited relatively small inter-limb asymmetries in strength, their asymmetries in GRF on-snow were relatively large.

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Ground Reaction Force Reduction of Biped Robot for Walking Along a Step with Dual Length Linear Inverted Pendulum Method

Journal of Robotics and Mechatronics ◽

10.20965/jrm.2013.p0220 ◽

2013 ◽

Vol 25 (1) ◽

pp. 220-231 ◽

Cited By ~ 4

Author(s):

Fariz Ali ◽

◽

Naoki Motoi ◽

Kirill Van Heerden ◽

Atsuo Kawamura

Keyword(s):

Inverted Pendulum ◽

Reaction Force ◽

Biped Robot ◽

Ground Reaction Forces ◽

Bipedal Robot ◽

Impact Forces ◽

Reaction Forces ◽

Left And Right ◽

Newton Raphson ◽

Force Reduction

A bipedal robot should be robust and able to move in various directions on stairs. However, up to date many research studies have been focusing on walking in the up or down direction only. Therefore, a strategy to realize walking along a step is investigated. In conventional methods, CoM is moved up or down during walking in this situation. In this paper, a method named as Dual Length Linear Inverted Pendulum Method (DLLIPM) with Newton-Raphson is proposed for 3-D biped robot walking. The proposed method applies different length of pendulum at left and right legs in order to represent the CoM height. By using the proposed method, maximum impact forces are reduced. From the Ground Reaction Forces (GRF) data obtained in the simulations, the validity of the proposed method is confirmed.

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Do tracks yield reliable information on gaits? – Part 1: The case of horses

Fossil Record ◽

10.5194/fr-17-59-2014 ◽

2014 ◽

Vol 17 (1) ◽

pp. 59-67 ◽

Cited By ~ 2

Author(s):

K. Kienapfel ◽

S. Läbe ◽

H. Preuschoft

Keyword(s):

Reliable Information ◽

Ground Reaction Forces ◽

Trunk Length ◽

Quadrupedal Locomotion ◽

Limb Bones ◽

Left Behind ◽

The World ◽

Reaction Forces ◽

Series Of Experiments ◽

Left And Right

Abstract. During their lifetime animals leave many tracks and traces behind, which can provide insights into the animals' behaviour. Single footprints of extant vertebrates are frequently found in sediments all over the world, often arranged into trackways. The study of footprints and trackways lead to interpretations about the mode of locomotion of the trackmaker. Here we show an approach to identify gaits from tracks. A series of experiments with horses was performed to determine whether gaits could be identified on the basis of fossil trackways, e.g. those left behind by sauropod dinosaurs of the Mesozoic era or Tertiary mammals, to unveil their locomotor abilities. The generally valid rules for quadrupedal locomotion were taken into consideration. Symmetrical gaits result in very similar trackways; a further differentiation can be made by application of statistics on step lengths, excursion angles and overstepping. A clear difference exists between the trot and the pace. These rapid, symmetric gaits imply high ground reaction forces (GRF) because of their long phases of aerial suspension at higher speeds. The resulting GRF seem to be too high to be sustained by the limb bones of huge graviportal animals like sauropods. Unfortunately, most of these factors are rarely available in the case of fossil tracks. Likewise, the asymmetrical, springing gaits can be excluded for sauropods because of the enormous GRF. Provided that limb length as well as trunk length can be approximated, and left and right, as well as forefoot and hindfoot imprints can be discriminated, the symmetrical gaits (walk, amble, pace, trot) used when making a trackway can be discerned.

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A Novel and Safe Approach to Simulate Cutting Movements Using Ground Reaction Forces

Sensors ◽

10.3390/s18082631 ◽

2018 ◽

Vol 18 (8) ◽

pp. 2631 ◽

Cited By ~ 1

Author(s):

Amelia Lanier ◽

Brian Knarr ◽

Nicholas Stergiou ◽

Thomas Buchanan

Keyword(s):

Force Control ◽

Cruciate Ligament ◽

Knee Injuries ◽

Force Production ◽

Ground Reaction Forces ◽

Control Task ◽

Significant Difference ◽

Reaction Forces ◽

Anterior Cruciate ◽

Force Profiles

Control of shear ground reaction forces (sGRF) is important in performing running and cutting tasks as poor sGRF control has implications for those with knee injuries, such as anterior cruciate ligament (ACL) ruptures. The goal of this study was to develop a novel and safe task to evaluate control or accurate modulation of shear ground reaction forces related to those generated during cutting. Our approach utilized a force control task using real-time visual feedback of a subject’s force production and evaluated control capabilities through accuracy and divergence measurements. Ten healthy recreational athletes completed the force control task while force control via accuracy measures and divergence calculations was investigated. Participants were able to accurately control sGRF in multiple directions based on error measurements. Forces generated during the task were equal to or greater than those measured during a number of functional activities. We found no significant difference in the divergence of the force profiles using the Lyapunov Exponent of the sGRF trajectories. Participants using our approach produced high accuracy and low divergence force profiles and functional force magnitudes. Moving forward, we will utilize this task in at-risk populations who are unable to complete a cutting maneuver in early stages of rehabilitation, such as ACL deficient and newly reconstructed individuals, allowing insight into force control not obtainable otherwise.

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

Journal of Applied Physiology ◽

10.1152/japplphysiol.00925.2018 ◽

2019 ◽

Vol 126 (5) ◽

pp. 1315-1325 ◽

Cited By ~ 3

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.

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Estimation of Ground Reaction Forces Based on Knee Joint Acceleration of Lower-Limb Exoskeletons

2020 International Automatic Control Conference (CACS) ◽

10.1109/cacs50047.2020.9289732 ◽

2020 ◽

Author(s):

Tesheng Hsiao ◽

Kinglam Yip ◽

Yun-Jen Chiu

Keyword(s):

Knee Joint ◽

Lower Limb ◽

Ground Reaction Forces ◽

Reaction Forces ◽

Joint Acceleration

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Ground Reaction Forces of Dressage Horses Performing the Piaffe

Animals ◽

10.3390/ani11020436 ◽

2021 ◽

Vol 11 (2) ◽

pp. 436 ◽

Cited By ~ 1

Author(s):

Hilary Mary Clayton ◽

Sarah Jane Hobbs

Keyword(s):

Coefficient Of Variation ◽

Three Dimensional ◽

Individual Variability ◽

The Other ◽

Ground Reaction Forces ◽

High Coefficient ◽

Reaction Forces

The piaffe is an artificial, diagonally coordinated movement performed in the highest levels of dressage competition. The ground reaction forces (GRFs) of horses performing the piaffe do not appear to have been reported. Therefore, the objective of this study was to describe three-dimensional GRFs in ridden dressage horses performing the piaffe. In-ground force plates were used to capture fore and hindlimb GRF data from seven well-trained dressage horses. Peak vertical GRF was significantly higher in forelimbs than in the hindlimbs (7.39 ± 0.99 N/kg vs. 6.41 ± 0.64 N/kg; p < 0.001) with vertical impulse showing a trend toward higher forelimb values. Peak longitudinal forces were small with no difference in the magnitude of braking or propulsive forces between fore and hindlimbs. Peak transverse forces were similar in magnitude to longitudinal forces and were mostly directed medially in the hindlimbs. Both the intra- and inter-individual variability of longitudinal and transverse GRFs were high (coefficient of variation 25–68%). Compared with the other diagonal gaits of dressage horses, the vertical GRF somewhat shifted toward the hindlimbs. The high step-to-step variability of the horizontal GRF components is thought to reflect the challenge of balancing on one diagonal pair of limbs with no forward momentum.

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