scholarly journals A Novel Method for Field Measurement of Ankle Joint Stiffness in Hopping

2021 ◽  
Vol 11 (24) ◽  
pp. 12140
Author(s):  
Sanubar Ghorbani Faal ◽  
Elham Shirzad ◽  
Ali Sharifnezhad ◽  
Mojtaba Ashrostaghi ◽  
Roozbeh Naemi
Keyword(s):  
Ankle Joint ◽  
Conventional Method ◽  
High Speed ◽  
Reaction Force ◽  
Force Plate ◽  
Joint Stiffness ◽  
New Method ◽  
Inverse Dynamic ◽  
Wide Range ◽  
Novel Method

Stiffness of ankle joint has been investigated in a wide range of biomechanical studies with a focus on the improvement of performance and reduction in the risk of injury. However, measuring ankle joint stiffness (AJS) using the existing conventional methodologies requires sophisticated equipment such as force plate and motion analyses systems. This study presents a novel method for measuring AJS during a hopping task with no force or motion measurement system. Also the validity of the proposed new method was investigated by comparing the results against those obtained using conventional method in which motion capture and force plate data are used. Twelve participants performed the controlled hopping task at 2.2 Hz, on a force platform, and six high speed cameras recorded the movement. To calculate the AJS in both methods, the lower extremity was modeled as a three linked rigid segments robot with three joints. In the new method, the contact time and flight time were used to calculate ground reaction force, and inverse kinematic and inverse dynamic approaches were used to calculate the ankle kinematic and kinetic. The AJS calculated using the new method was compared against the results of conventional method as the reference. The calculated AJS using this new method (506.47 ± 177.84 N·m/rad) showed a significant correlation (r = 0.752) with the AJS calculated using conventional method (642.39 ± 185.96 N·m/rad). The validation test showed a mean difference of −24.76% using Bland–Altman plot. The presented method can be used as a valid, and low-cost tool for assessing AJS in the field in low resource settings.

Is Soleus Muscle-Tendon-Unit Behavior Related to Ground-Force Application During the Sprint Start?

2017 ◽  
Vol 12 (4) ◽  
pp. 448-454 ◽  
Author(s):  
Erik Schrödter ◽  
Gert-Peter Brüggemann ◽  
Steffen Willwacher
Keyword(s):  
Ankle Joint ◽  
High Speed ◽  
Plantar Flexion ◽  
Systematic Observation ◽  
Performance Levels ◽  
Muscle Fascicle ◽  
Wide Range ◽  
Stretch Shortening Cycle ◽  
And Performance ◽  
Upper Ankle

Purpose:To describe the stretch-shortening behavior of ankle plantar-flexing muscle–tendon units (MTUs) during the push-off in a sprint start.Methods:Fifty-four male (100-m personal best: 9.58–12.07 s) and 34 female (100-m personal best: 11.05–14.00 s) sprinters were analyzed using an instrumented starting block and 2-dimensional high-speed video imaging. Analysis was performed separately for front and rear legs, while accounting for block obliquities and performance levels.Results:The results showed clear signs of a dorsiflexion in the upper ankle joint (front block 15.8° ± 7.4°, 95% CI 13.2–18.2°; rear block 8.0° ± 5.7°, 95% CI 6.4–9.7°) preceding plantar flexion. When observed in their natural block settings, the athletes’ block obliquity did not significantly affect push-off characteristics. It seems that the stretch-shortening-cycle-like motion of the soleus MTU has an enhancing influence on push-off force generation.Conclusion:This study provides the first systematic observation of ankle-joint stretch-shortening behavior for sprinters of a wide range of performance levels. The findings highlight the importance of reactive-type training for the improvement of starting performance. Nonetheless, future studies need to resolve the independent contributions of tendinous and muscle-fascicle structures to overall MTU performance.

The Within-Subjects Effects of Practice on Performance of Drop Landing in Healthy, Young Adults

Motor Control ◽  
2020 ◽  
Vol 24 (1) ◽  
pp. 39-56
Author(s):  
James Hackney ◽  
Jade McFarland ◽  
David Smith ◽  
Clinton Wallis
Keyword(s):  
Young Adults ◽  
Ground Reaction Force ◽  
High Speed ◽  
Reaction Force ◽  
Force Plate ◽  
Jump Height ◽  
Lower Body ◽  
Variable Measure ◽  
Drop Landing ◽  
Within Subjects

Most studies of high-speed lower body movements include practice repetitions for facilitating consistency between the trials. We investigated whether 20 repetitions of drop landing (from a 30.5-cm platform onto a force plate) could improve consistency in maximum ground reaction force, linear lower body stiffness, depth of landing, and jump height in 20 healthy, young adults. Coefficient of variation was the construct for variability used to compare the first to the last five repetitions for each variable. We found that the practice had the greatest effect on maximum ground reaction force (p = .017), and had smaller and similar effects on lower body stiffness and depth of landing (p values = .074 and .044, respectively), and no measurable effect on jump height. These findings suggest that the effect of practice on drop landing differs depending upon the variable measure and that 20 repetitions significantly improve consistency in ground reaction force.

A New Method on Super Pixel Reducing Stereo Matching Time of Integrated Imaging

2020 ◽  
pp. 2154014
Author(s):  
Xue-Guang Wang ◽  
Ming Li ◽  
Lei Zhang ◽  
Hui Zhao ◽  
Thelma D. Palaoag
Keyword(s):  
3D Reconstruction ◽  
Conventional Method ◽  
Stereo Vision ◽  
Stereo Matching ◽  
Technical Difficulty ◽  
New Method ◽  
Matching Algorithm ◽  
The Core ◽  
Pixel Matching ◽  
Novel Method

Stereo vision and 3D reconstruction technologies are increasingly concerned in many fields. Stereo matching algorithm is the core of stereo vision and also a technical difficulty. A novel method based on super pixels is mentioned in this paper to reduce the calculating amount and the time. Stereo images from University of Tsukuba are used to test our method. The proposed method spends only 1% of the time spent by the conventional method. Through a two-step super-pixel matching optimization, it takes 6.72 s to match a picture, which is 12.96% of the pre-optimization.

A basic design for automotive crash boxes using an efficient corrugated conical tube

2021 ◽  
pp. 095440702199092
Author(s):  
Alireza Mortazavi Moghaddam ◽  
Atefeh Kheradpisheh ◽  
Masoud Asgari
Keyword(s):  
High Speed ◽  
General Procedure ◽  
Reaction Force ◽  
Passenger Cars ◽  
Detail Design ◽  
Thin Walled Structures ◽  
Wide Range ◽  
Vehicle Structure ◽  
Thin Walled ◽  
Guide Lines

Frontal vehicle structure is of high importance through crash energy managements and crash boxes are the fundamental structural component for vehicle safety as well as after sales issues. Similar to many other vehicle components, the detail design of crash box is usually part of manufacture knowhow. However, some guide lines are always available. In this article a general procedure is introduced for designing of crash box with the aid of novel thin walled structures and according to conventional crash scenarios. The problem is followed through some basic steps. Firstly, the crash box idea is selected through a wide range of previous investigated elements and is packaged in a real bench vehicle. Then thanks to the protection provided by the new crash box on the other more expensive components (e.g. headlamp, cooling pack, etc.), the effectiveness of this element are acknowledged through the low speed offset crash. Further on the robustness of new proposed crash box is approved by high speed crash simulations. The quasi-static simulations implemented during the analyses are carried out by finite element explicit code (Abaqus) and the FE modeling and dynamic simulation through the next steps are also performed in ANSA and PAM CRASH respectively. Finally in addition to the general crash box design proposed procedure, the achieved results demonstrated that the corrugated conical thin walled tubes deforms in regular and rather stable shape under both axial and oblique loadings. They also produced a reasonable reaction force versus deformations which leads to stiff and crashworthy energy absorber in comparison to traditional rectangular and even some special models like as origami shapes, and so they could be a valuable selection for crash box implementations in passenger cars.

scholarly journals Effect of Football Shoe Collar Type on Ankle Biomechanics and Dynamic Stability during Anterior and Lateral Single-Leg Jump Landings

2020 ◽  
Vol 10 (10) ◽  
pp. 3362
Author(s):  
Yunqi Tang ◽  
Zhikang Wang ◽  
Yifan Zhang ◽  
Shuqi Zhang ◽  
Shutao Wei ◽  
...  
Keyword(s):  
Dynamic Stability ◽  
Ankle Joint ◽  
Force Plate ◽  
Joint Stiffness ◽  
Lower Limbs ◽  
Jump Landing ◽  
Ankle Inversion ◽  
Reaction Forces ◽  
Ankle Biomechanics ◽  
Jump Landings

In this study, we investigated the effects of football shoes with different collar heights on ankle biomechanics and dynamic postural stability. Fifteen healthy college football players performed anterior and lateral single-leg jump landings when wearing high collar, elastic collar, or low collar football shoes. The kinematics of lower limbs and ground reaction forces were collected by simultaneously using a stereo-photogrammetric system with markers (Vicon) and a force plate (Kistler). During the anterior single-leg jump landing, a high collar shoe resulted in a significantly smaller ankle dorsiflexion range of motion (ROM), compared to both elastic (p = 0.031, dz = 0.511) and low collar (p = 0.043, dz = 0.446) types, while also presenting lower total ankle sagittal ROM, compared to the low collar type (p = 0.023, dz = 0.756). Ankle joint stiffness was significantly greater for the high collar, compared to the elastic collar (p = 0.003, dz = 0.629) and low collar (p = 0.030, dz = 1.040). Medial-lateral stability was significantly improved with the high collar, compared to the low collar (p = 0.001, dz = 1.232). During the lateral single-leg jump landing, ankle inversion ROM (p = 0.028, dz = 0.615) and total ankle frontal ROM (p = 0.019, dz = 0.873) were significantly smaller for the high collar, compared to the elastic collar. The high collar also resulted in a significantly smaller total ankle sagittal ROM, compared to the low collar (p = 0.001, dz = 0.634). Therefore, the high collar shoe should be effective in decreasing the amount of ROM and increasing the dynamic stability, leading to high ankle joint stiffness due to differences in design and material characteristics of the collar types.

scholarly journals A Novel Method for Measurement of Ankle Joint Reaction Force and Response to Syndesmotic Injury

2016 ◽  
Vol 1 (1) ◽  
pp. 2473011416S0000
Author(s):  
Meghan Kelly ◽  
Noorullah Maqsoodi ◽  
Daniel Vasconcellos ◽  
Walid Osman ◽  
Irvin C. Oh ◽  
...  
Keyword(s):  
Ankle Joint ◽  
Reaction Force ◽  
Syndesmotic Injury ◽  
Joint Reaction Force ◽  
Novel Method ◽  
Joint Reaction

scholarly journals The Midfoot Contributes to Power and Work During Single-limb Heel Rise

2018 ◽  
Vol 3 (3) ◽  
pp. 2473011418S0004
Author(s):  
Frank DiLiberto ◽  
Deborah Nawoczenski
Keyword(s):  
Energy Production ◽  
Reaction Force ◽  
Force Plate ◽  
Healthy Adults ◽  
Joint Torque ◽  
Muscle Performance ◽  
Positive Power ◽  
Inverse Dynamic ◽  
Negative Power ◽  
Foot Function

Category: Midfoot/Forefoot Introduction/Purpose: Single-limb heel rise (HR) is used to evaluate muscle performance and clinical outcomes in people with foot and ankle pathology. While the midfoot contributes 13% of total foot/ankle work to forward propulsion during gait, healthy HR performance remains primarily characterized by ankle function. Similar to its function during gait, the midfoot may also generate power during HR to provide the stability needed for ankle push-off power. Further characterization of HR performance by evaluating midfoot kinetics may advance understanding of foot function in the clinical application of the HR task. The purpose of this study was to examine ankle and midfoot power and work during single-limb HR in healthy adults. Methods: Twelve healthy adults [Mean (SD): Age 31.3 (4.9) years; BMI 25.2 (3.3) Kg/m2; 50% male] performed twenty barefoot single-limb heel rises. Multi-segment kinematic and ground reaction force data were recorded with an electromagnetic motion capture system and force plate. Subject-specific, three segment foot models (tibia, rearfoot, forefoot) were derived. Inverse dynamic calculations were performed to obtain ankle and midfoot peak positive and negative powers (joint torque x segmental velocity), as well as the timing of peak powers (% of the heel rise). Midfoot work (integral of power with respect to time), reflecting energy production, was examined as a percentage of the entire work performed at the ankle and midfoot during HR. Group descriptive data were examined as mean (standard deviation) [95% confidence interval]. Results: Ankle peak positive power was 2.8 (0.8) [2.2 - 3.3] W/Kg and occurred during the ascent phase at 7% HR (Figure 1). Midfoot peak positive power was 0.5 (0.2) [0.3 - 0.6] W/Kg occurring at 6%. Ankle peak negative power was 2.1 (0.6) [1.7 - 2.4] W/Kg and occurred during the descent phase at 84% HR. Midfoot peak negative power was 0.4 (0.2) [0.2 - 0.5] W/Kg occurring at 83%. The proportion of midfoot work to total work performed was 13.5 (5.7) [9.8 - 17.1] %. Conclusion: Study findings advance understanding of foot function by demonstrating the contribution of midfoot power and work during HR in healthy adults. Midfoot peak powers were approximately 18% of ankle powers and occurred at similar times during HR. Further, midfoot energy production appears to be an important aspect of healthy HR performance because approximately 14% of the total foot/ankle work occurs at the midfoot. Since active internal muscle and ligament mechanisms are attributed to midfoot power generation, practitioners should consider midfoot tissue loading and muscle performance when implementing the HR task in clinical practice.

Evaluation and application of magnetizable charcoal for separation in radioimmunoassays.

1979 ◽  
Vol 25 (8) ◽  
pp. 1402-1405 ◽  
Author(s):  
E A Al-Dujaili ◽  
G C Forrest ◽  
C R Edwards ◽  
J Landon
Keyword(s):  
Conventional Method ◽  
Coefficient Of Variation ◽  
Detailed Comparison ◽  
Separation Method ◽  
Wide Range ◽  
Small Polypeptide ◽  
Polypeptide Hormones ◽  
Novel Method ◽  
Free Antigen

Abstract We compared conventional charcoal separation of antibody-bound and free antigen with a novel method involving magnetizable particles containing charcoal. The magnetizable charcoal separation method was as effective as the conventional method for a wide range of radioimmunoassays, including those for several steroids and small polypeptide hormones. In a detailed comparison of conventional vs. magnetizable charcoal for radioimmunoassay of aldosterone, the magnetizable charcoal had several advantages: it did not require prior coating with dextran or protein, varied less with time and temperature, required no centrifugation, and took less time for separation. The correlation of results obtained with magnetizable and conventional charcoal separation was excellent (n = 89, r = 0.98, p less than 0.001), and the coefficient of variation for the separation with magnetizable charcoal was 0.5%.

Biomechanics of Youth Windmill Softball Pitching

2005 ◽  
Vol 33 (4) ◽  
pp. 552-560 ◽  
Author(s):  
Sherry L. Werner ◽  
John A. Guido ◽  
Ryan P. McNeice ◽  
Jasper L. Richardson ◽  
Neil A. Delude ◽  
...  
Keyword(s):  
Body Weight ◽  
Lower Extremity ◽  
High Speed ◽  
Reaction Force ◽  
Force Plate ◽  
Three Dimensional ◽  
Research Attention ◽  
Joint Torques ◽  
Baseball Pitchers ◽  
Force Components

Background Limited research attention has been paid to the potentially harmful windmill softball pitch. No information is available regarding lower extremity kinetics in softball pitching. Hypothesis The stresses on the throwing arm of youth windmill pitchers are clinically significant and similar to those found for college softball pitchers. Study Design Descriptive laboratory study. Methods Three-dimensional, high-speed (240-Hz) video and stride foot force plate (1200 Hz) data were collected on fastballs from 53 youth softball pitchers. Kinematic parameters related to pitching mechanics and resultant kinetics on the throwing-arm elbow and shoulder joints were calculated. Kinetic parameters were compared to those reported for baseball pitchers. Results Elbow and shoulder joint loads were similar to those found for baseball pitchers and college softball pitchers. Shoulder distraction stress averaged 94% body weight for the youth pitchers. Stride foot ground reaction force patterns were not similar to those reported for baseball pitchers. Vertical and braking force components under the stride foot were in excess of body weight. Conclusions Excessive distraction stress and joint torques at the throwing-arm elbow and shoulder are similar to those found in baseball pitchers, which suggests that windmill softball pitchers are at risk for overuse injuries. Normative information regarding upper and lower extremity kinematics and kinetics for 12- to 19-year-old softball pitchers has been established.

Microfabrication research at the National Submicron Facility

1983 ◽  
Vol 41 ◽  
pp. 86-89
Author(s):  
E.D. Wolf
Keyword(s):  
Integrated Circuits ◽  
Particle Physics ◽  
High Speed ◽  
New Technology ◽  
High Energy ◽  
High Energy Particle ◽  
New Science ◽  
Wide Range ◽  
Intermediate Domain ◽  
Circuit Function

Most microelectronics devices and circuits operate faster, consume less power, execute more functions and cost less per circuit function when the feature-sizes internal to the devices and circuits are made smaller. This is part of the stimulus for the Very High-Speed Integrated Circuits (VHSIC) program. There is also a need for smaller, more sensitive sensors in a wide range of disciplines that includes electrochemistry, neurophysiology and ultra-high pressure solid state research. There is often fundamental new science (and sometimes new technology) to be revealed (and used) when a basic parameter such as size is extended to new dimensions, as is evident at the two extremes of smallness and largeness, high energy particle physics and cosmology, respectively. However, there is also a very important intermediate domain of size that spans from the diameter of a small cluster of atoms up to near one micrometer which may also have just as profound effects on society as “big” physics.

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