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 Kinematics of Usain Bolt’s maximal sprint velocity

Kinesiology ◽  
2018 ◽  
Vol 50 (2) ◽  
pp. 172-180 ◽  
Author(s):  
Milan Čoh ◽  
Kim Hébert-Losier ◽  
Stanko Štuhec ◽  
Vesna Babić ◽  
Matej Supej
Keyword(s):  
Ground Reaction Force ◽  
High Speed ◽  
Reaction Force ◽  
Vertical Displacement ◽  
Biomechanical Analysis ◽  
Maximal Velocity ◽  
Vertical Ground Reaction Force ◽  
Mean Velocity ◽  
Vertical Ground ◽  
Sprint Velocity

This study investigated the maximal sprint velocity kinematics of the fastest 100 m sprinter, Usain Bolt. Two high-speed video cameras recorded kinematics from 60 to 90 m during the men 100 m final at the IAAF World Challenge Zagreb 2011, Croatia. Despite a relatively slow reaction time (194 ms), Bolt won in 9.85 s (mean velocity: 10.15 m/s). His fastest 20-m section velocity was 12.14 m/s, reached between 70 and 90 m, by 2.70-m long strides and 4.36 strides/s frequency. At the maximal velocity, his contact and flight times were 86 and 145 ms, respectively, and vertical ground reaction force generated equalled 4.2 times his body weight (3932 N). The braking and propulsion phase represented 37% and 63% of ground contact, respectively, with his centre of mass (CoM) exhibiting minor reductions in horizontal velocity (2.7%) and minimal vertical displacement (4.9 cm). Emerged Bolt’s maximal sprint velocity and international predominance from coordinated motor abilities, power generation capacities, and effective technique. This study confirms that his maximal velocity was achieved by means of relatively long strides, minimal braking phase, high vertical ground reaction force, and minimal vertical displacement of CoM. This study is the first in-depth biomechanical analysis of Bolt’s maximal sprinting velocity with the segmental reconstruction.

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.

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 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.

scholarly journals Acute Effects of Handheld Loading on Standing Broad Jump in Youth Athletes

2021 ◽  
Vol 18 (9) ◽  
pp. 5046
Author(s):  
Wei-Hsun Tai ◽  
Ray-Hsien Tang ◽  
Chen-Fu Huang ◽  
Shin-Liang Lo ◽  
Yu-Chi Sung ◽  
...  
Keyword(s):  
High Speed ◽  
Center Of Mass ◽  
Reaction Force ◽  
Sampling Rate ◽  
Random Order ◽  
Horizontal Distance ◽  
Acute Effects ◽  
Vertical Ground Reaction Force ◽  
Strength And Conditioning ◽  
Peak Knee

The study aimed to investigate the acute effects of handheld loading on standing broad jump (SBJ) performance and biomechanics. Fifteen youth male athletes (mean age: 14.7 ± 0.9 years; body mass: 59.3 ± 8.0 kg; height: 1.73 ± 0.07 m) volunteered to participate in the study. Participants were assigned to perform SBJ with and without 4 kg dumbbells in a random order. Kinematic and kinetic data were collected using 10 infrared high-speed motion-capture cameras at a 250 Hz sampling rate and two force platforms at a 1000 Hz sampling rate. A paired t-test was applied to all variables to determine the significance between loading and unloading SBJs. Horizontal distance (p < 0.001), take-off distance (p = 0.001), landing distance (p < 0.001), horizontal velocity of center of mass (CoM; p < 0.001), push time (p < 0.001), vertical impulse (p = 0.003), and peak horizontal and vertical ground reaction force (GRF; p < 0.001, p = 0.017) were significantly greater in loading SBJ than in unloading SBJ. The take-off vertical velocity of CoM (p = 0.001), take-off angle (p < 0.001), peak knee and hip velocity (p < 0.001, p = 0.007), peak ankle and hip moment (p = 0.006, p = 0.011), and peak hip power (p = 0.014) were significantly greater in unloading SBJ than in loading SBJ. Conclusions: Acute enhancement in SBJ performance was observed with handheld loading. The present findings contribute to the understanding of biomechanical differences in SBJ performance with handheld loading and are highly applicable to strength and conditioning training for athletes.

scholarly journals A Systematic Approach to the Design and Characterization of a Smart Insole for Detecting Vertical Ground Reaction Force (vGRF) in Gait Analysis

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 957 ◽  
Author(s):  
Anas M. Tahir ◽  
Muhammad E. H. Chowdhury ◽  
Amith Khandakar ◽  
Sara Al-Hamouz ◽  
Merna Abdalla ◽  
...  
Keyword(s):  
Gait Analysis ◽  
Reaction Force ◽  
Applied Pressure ◽  
Pressure Sensors ◽  
Clinical Diagnostics ◽  
Piezoelectric Sensors ◽  
Sensor Calibration ◽  
Vertical Ground Reaction Force ◽  
Vertical Ground ◽  
Smart Insole

Gait analysis is a systematic study of human locomotion, which can be utilized in various applications, such as rehabilitation, clinical diagnostics and sports activities. The various limitations such as cost, non-portability, long setup time, post-processing time etc., of the current gait analysis techniques have made them unfeasible for individual use. This led to an increase in research interest in developing smart insoles where wearable sensors can be employed to detect vertical ground reaction forces (vGRF) and other gait variables. Smart insoles are flexible, portable and comfortable for gait analysis, and can monitor plantar pressure frequently through embedded sensors that convert the applied pressure to an electrical signal that can be displayed and analyzed further. Several research teams are still working to improve the insoles’ features such as size, sensitivity of insoles sensors, durability, and the intelligence of insoles to monitor and control subjects’ gait by detecting various complications providing recommendation to enhance walking performance. Even though systematic sensor calibration approaches have been followed by different teams to calibrate insoles’ sensor, expensive calibration devices were used for calibration such as universal testing machines or infrared motion capture cameras equipped in motion analysis labs. This paper provides a systematic design and characterization procedure for three different pressure sensors: force-sensitive resistors (FSRs), ceramic piezoelectric sensors, and flexible piezoelectric sensors that can be used for detecting vGRF using a smart insole. A simple calibration method based on a load cell is presented as an alternative to the expensive calibration techniques. In addition, to evaluate the performance of the different sensors as a component for the smart insole, the acquired vGRF from different insoles were used to compare them. The results showed that the FSR is the most effective sensor among the three sensors for smart insole applications, whereas the piezoelectric sensors can be utilized in detecting the start and end of the gait cycle. This study will be useful for any research group in replicating the design of a customized smart insole for gait analysis.

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