The Snatch Technique of World Class Weightlifters at the 1985 World Championships

1988 ◽  
Vol 4 (1) ◽  
pp. 68-89 ◽  
Author(s):  
Wolfgang Baumann ◽  
Volker Gross ◽  
Karl Quade ◽  
Peter Galbierz ◽  
Ansgar Schwirtz
Keyword(s):  
Knee Joint ◽  
Kinetic Parameters ◽  
Reaction Force ◽  
Three Dimensional ◽  
Joint Moments ◽  
Total Load ◽  
Precise Control ◽  
Lifting Technique ◽  
Reaction Forces ◽  
Knee Joint Moment

The purpose of this study was (a) to describe the snatch technique in terms of kinematic and external and internal kinetic parameters, and (b) to compare the results for athletes of different groups and weight categories. By means of three-dimensional film analysis and measurements of ground reaction forces during the 1985 World Championships in Sweden, it was possible to analyze the spatial movements and to calculate joint moments of force in each leg. Concerning the kinematics, a snatch technique starting with a strong pull toward the lifter could be established. The most interesting kinetic results are that the knee joint moments are relatively small (one third of the hip joint moments of force) and do not correlate very well with the total load. The best lifters seem able to limit the knee joint moment by precise control of the knee position with respect to the ground reaction force. Altogether, the results concerning the internal kinetic parameters question the logic of the classical division of the lifting technique into phases according to external kinetic parameters.

Three-Dimensional Knee Joint Moments During Performance of the Bodyweight Squat: Effects of Stance Width and Foot Rotation

2013 ◽  
Vol 29 (1) ◽  
pp. 33-43 ◽  
Author(s):  
Sivan Almosnino ◽  
David Kingston ◽  
Ryan B. Graham
Keyword(s):  
Knee Joint ◽  
Internal Rotation ◽  
Rotation Angle ◽  
Three Dimensional ◽  
Principal Component ◽  
Moment Magnitude ◽  
Joint Moments ◽  
Flexion Moment ◽  
Knee Joint Moment ◽  
Healthy Participants

The purpose of this investigation was to assess the effects of stance width and foot rotation angle on three-dimensional knee joint moments during bodyweight squat performance. Twenty-eight participants performed 8 repetitions in 4 conditions differing in stance or foot rotation positions. Knee joint moment waveforms were subjected to principal component analysis. Results indicated that increasing stance width resulted in a larger knee flexion moment magnitude, as well as larger and phase-shifted adduction moment waveforms. The knee’s internal rotation moment magnitude was significantly reduced with external foot rotation only under the wide stance condition. Moreover, squat performance with a wide stance and externally rotated feet resulted in a flattening of the internal rotation moment waveform during the middle portion of the movement. However, i is speculated that the differences observed across conditions are not of clinical relevance for young, healthy participants.

scholarly journals Machine Learning-Based Estimation of Ground Reaction Forces and Knee Joint Kinetics from Inertial Sensors While Performing a Vertical Drop Jump

Sensors ◽  
2021 ◽  
Vol 21 (22) ◽  
pp. 7709
Author(s):  
Serena Cerfoglio ◽  
Manuela Galli ◽  
Marco Tarabini ◽  
Filippo Bertozzi ◽  
Chiarella Sforza ◽  
...  
Keyword(s):  
Neural Network ◽  
Machine Learning ◽  
Knee Joint ◽  
Field Analysis ◽  
Ground Reaction Forces ◽  
Drop Jump ◽  
Joint Moments ◽  
Data Set ◽  
Joint Kinetics ◽  
Reaction Forces

Nowadays, the use of wearable inertial-based systems together with machine learning methods opens new pathways to assess athletes’ performance. In this paper, we developed a neural network-based approach for the estimation of the Ground Reaction Forces (GRFs) and the three-dimensional knee joint moments during the first landing phase of the Vertical Drop Jump. Data were simultaneously recorded from three commercial inertial units and an optoelectronic system during the execution of 112 jumps performed by 11 healthy participants. Data were processed and sorted to obtain a time-matched dataset, and a non-linear autoregressive with external input neural network was implemented in Matlab. The network was trained through a train-test split technique, and performance was evaluated in terms of Root Mean Square Error (RMSE). The network was able to estimate the time course of GRFs and joint moments with a mean RMSE of 0.02 N/kg and 0.04 N·m/kg, respectively. Despite the comparatively restricted data set and slight boundary errors, the results supported the use of the developed method to estimate joint kinetics, opening a new perspective for the development of an in-field analysis method.

Simulation Research of Top-Hung Mechanism for Open and Close

2014 ◽  
Vol 644-650 ◽  
pp. 416-420
Author(s):  
Xu Zhou ◽  
Ying Wu
Keyword(s):  
Simulation Analysis ◽  
Reaction Force ◽  
Three Dimensional ◽  
Revolute Joint ◽  
Initial Values ◽  
Support Reaction ◽  
Vertical Location ◽  
Optimization Parameters ◽  
Reaction Forces ◽  
Set Up

For the purpose of researching the top-hung mechanism for open and close and the improvement and use of the mechanism, improving the work efficiency, the three-dimensional solid model of the mechanism was established with ADAMS. Each part of the model in ADAMS was set up. Simulation analysis on the working process of the mechanism was achieved. The structure optimization parameters of the mechanism were obtained. The result proves that when the vertical location of the upper endpoint of lid was increased the total support reaction force acting on the lower endpoint of lower rocker by frame reduced. When the horizontal location of revolute joint of lower rocker and frame, the horizontal location of revolute joint of lower rocker and lid were increased the total support reaction forces acting on the lower endpoint of lower rocker by frame added. The sensitivities of the total support reaction forces acting on the lower endpoint of lower rocker by frame on the initial values of the locations of revolute joint of lower rocker and link, the horizontal location of revolute joint of lower rocker and frame are greater. The sensitivities of the total support reaction forces acting on the lower endpoint of lower rocker by frame on the initial values of the vertical location of revolute joint of upper rocker and link, the horizontal location of revolute joint of the lower rocker and lid are smaller. The sensitivity of the total support reaction force acting on the lower endpoint of lower rocker by frame on the initial value of the vertical location of the upper endpoint of lid are least.

Temporal Influences of Functional Knee Bracing on Torque Production of the Lower Extremity

2006 ◽  
Vol 15 (3) ◽  
pp. 215-227
Author(s):  
Brian Campbell ◽  
James Yaggie ◽  
Daniel Cipriani
Keyword(s):  
Lower Extremity ◽  
Outcome Measures ◽  
Repeated Measures ◽  
Exercise Intervention ◽  
Three Dimensional ◽  
Exercise Program ◽  
Joint Moments ◽  
Repeated Measures Design ◽  
Reaction Forces ◽  
Vertical Ground Reaction Forces

Context:Functional knee braces (FKB) are used prophylactically and in rehabilitation to aide in the functional stability of the knee.Objective:To determine if alterations in select lower extremity moments persist throughout a one hour period in healthy individuals.Design:2X5 repeated measures design.Setting:Biomechanics Laboratory.Subjects:Twenty subjects (14 male and 6 female, mean age 26.5±7 yrs; height 172.4±13 cm; weight 78.6±9 kg), separated into braced (B) and no brace (NB) groups.Intervention:A one-hour exercise program divided into three 20 minute increments.Main Outcome Measures:Synchronized three-dimensional kinematic and kinetic data were collected at 20-minute increments to assess the effect of the FKB on select lower extremity moments and vertical ground reaction forces.Results:Increase in hip moment and a decrease in knee moment were noted immediately after brace application and appeared to persist throughout a one hour bout of exercise.Conclusions:The FKB and the exercise intervention caused decreases in knee joint moments and increases in hip joint moments.

scholarly journals A data set with kinematic and ground reaction forces of human balance

2017 ◽  
Author(s):  
Damiana A dos Santos ◽  
Claudiane A Fukuchi ◽  
Reginaldo K Fukuchi ◽  
Marcos Duarte
Keyword(s):  
Center Of Pressure ◽  
Reaction Force ◽  
Kinematic Model ◽  
Three Dimensional ◽  
Force Platform ◽  
Whole Body ◽  
Ground Reaction Forces ◽  
Data Set ◽  
Public Data ◽  
Reaction Forces

This article describes a public data set with the three-dimensional kinematics of the whole body and the ground reaction forces (with a dual force platform setup) of subjects standing still for 60 s in different conditions, in which the vision and the standing surface were manipulated. Twenty-seven young subjects and 22 old subjects were evaluated. The data set comprises a file with metadata plus 1,813 files with the ground reaction force (GRF) and kinematics data for the 49 subjects (three files for each of the 12 trials plus one file for each subject). The file with metadata has information about each subject’s sociocultural, demographic, and health characteristics. The files with the GRF have the data from each force platform and from the resultant GRF (including the center of pressure data). The files with the kinematics have the three-dimensional position of the 42 markers used for the kinematic model of the whole body and the 73 calculated angles. In this text, we illustrate how to access, analyze, and visualize the data set. All the data is available at Figshare (DOI: 10.6084/m9.figshare.4525082 ), and a companion Jupyter Notebook (available at https://github.com/demotu/datasets ) presents the programming code to generate analyses and other examples.

scholarly journals A data set with kinematic and ground reaction forces of human balance

2017 ◽  
Author(s):  
Damiana A dos Santos ◽  
Claudiane A Fukuchi ◽  
Reginaldo K Fukuchi ◽  
Marcos Duarte
Keyword(s):  
Center Of Pressure ◽  
Reaction Force ◽  
Kinematic Model ◽  
Three Dimensional ◽  
Force Platform ◽  
Whole Body ◽  
Ground Reaction Forces ◽  
Data Set ◽  
Public Data ◽  
Reaction Forces

This article describes a public data set with the three-dimensional kinematics of the whole body and the ground reaction forces (with a dual force platform setup) of subjects standing still for 60 s in different conditions, in which the vision and the standing surface were manipulated. Twenty-seven young subjects and 22 old subjects were evaluated. The data set comprises a file with metadata plus 1,813 files with the ground reaction force (GRF) and kinematics data for the 49 subjects (three files for each of the 12 trials plus one file for each subject). The file with metadata has information about each subject’s sociocultural, demographic, and health characteristics. The files with the GRF have the data from each force platform and from the resultant GRF (including the center of pressure data). The files with the kinematics have the three-dimensional position of the 42 markers used for the kinematic model of the whole body and the 73 calculated angles. In this text, we illustrate how to access, analyze, and visualize the data set. All the data is available at Figshare (DOI: 10.6084/m9.figshare.4525082 ), and a companion Jupyter Notebook (available at https://github.com/demotu/datasets ) presents the programming code to generate analyses and other examples.

Foot Rotation Gait Modifications Affect Hip and Ankle, But Not Knee, Stance Phase Joint Reaction Forces During Running

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Hunter J. Bennett ◽  
Kevin A. Valenzuela ◽  
Scott K. Lynn ◽  
Joshua T. Weinhandl
Keyword(s):  
Knee Joint ◽  
Stance Phase ◽  
External Rotation ◽  
Three Dimensional ◽  
Statistical Parametric Mapping ◽  
Muscle Physiology ◽  
Total Force ◽  
Joint Reaction Forces ◽  
Reaction Forces ◽  
Joint Reaction

Abstract Alterations of foot rotation angles have successfully reduced external knee adduction moments during walking and running. However, reductions in knee adduction moments may not result in reductions in knee joint reaction forces. The purpose of this study was to examine the effects of internal and external foot rotation on knee, hip, and ankle joint reaction forces during running. Motion capture and force data were recorded of 19 healthy adults running at 3.35 m/s during three conditions: (1) preferred (normal) and with (2) internal and (3) external foot rotation. Musculoskeletal simulations were performed using opensim and the Rajagopal 2015 model, modified to a two degree-of-freedom knee joint. Muscle excitations were derived using static optimization, including muscle physiology parameters. Joint reaction forces (i.e., the total force acting on the joints) were computed and compared between conditions using one-way analyses of variance (ANOVAs) via statistical parametric mapping (SPM). Internal foot rotation reduced resultant hip forces (from 18% to 23% stride), while external rotation reduced resultant ankle forces (peak force at 20% stride) during the stance phase. Three-dimensional and resultant knee joint reaction forces only differed at very early and very late stance phase. The results of this study indicate, similar to previous findings, that reductions in external knee adduction moments do not mirror reductions in knee joint reaction forces.

Dynamic Response of Human Legs due to Horizontal Jump

2012 ◽  
Author(s):  
Srikanth Ravuri ◽  
Fred Barez ◽  
David Wagner ◽  
Jim Kao
Keyword(s):  
Reaction Force ◽  
Three Dimensional ◽  
Simulation Software ◽  
Leap Motion ◽  
Biomechanical Simulation ◽  
Maximum Reaction ◽  
Internal Joint ◽  
Joint Reaction Forces ◽  
Reaction Forces ◽  
Distal Direction

Jumping is a coordinated extension of the human body through combined strength and agility to perform a leap motion far enough for the feet to land on the ground. However, the repeated reaction forces and the resulting stresses on the ankle, knee and hip joints may cause injuries to a person. A primary mechanism of such injuries is suggested to be the acute high impact loads experienced during the landing in a horizontal jump. The goal of this study is to determine the reaction force distribution at the joints in the lower extremities during the horizontal jump. A detailed biomechanical system was constructed to calculate the reaction forces generated during the horizontal jump. The horizontal jump kinematics of a participant was measured using a three-dimensional motion capture system and the landing forces were measured using two force plates. Biomechanical simulation software was used to calculate the internal joint reaction forces at the ankle, knee, and hip. It was determined that the maximum reaction forces primarily occurred in the proximo/distal direction of the hip, 2,300 N; and ankle, 2,700 N. However, at the knee joint, the maximum reaction force was determined to be in antero/posterior direction, at 2,000 N; and proximo/distal direction, at 2,100 N, respectively.

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