Kinematics and Kinetics of the Racket-Arm during the Soft-Tennis Smash under Match Conditions

2005 ◽  
Vol 21 (4) ◽  
pp. 334-347 ◽  
Author(s):  
Hirofumi Ida ◽  
Seiji Kusubori ◽  
Motonobu Ishii
Keyword(s):  
Time Pressure ◽  
Swing Phase ◽  
Joint Torque ◽  
Elbow Extension ◽  
Competitive Situation ◽  
Match Play ◽  
Joint Torques ◽  
Tennis Serve ◽  
Kinetics Of ◽  
Kinematics And Kinetics

The purposes of this study were to (a) describe the racket-arm kinematics and kinetics of the soft-tennis smash during match rallies, and (b) assess the characteristics of this smash vs. the laboratory-simulated smash of our previous study. In the current study we recorded soft-tennis smash motions during match play of the 3rd East Asian Games. Racket-arm anatomical joint angular velocity and anatomical joint torque were calculated from 3-D coordinate data of 13 collected motions obtained using the direct linear transformation procedure. The results showed that most of the maximum values of the anatomical joint torques were qualitatively smaller than those of the tennis serve. Peak elbow extension, shoulder internal rotation, and elbow varus torques in match play were significantly greater than values reported for laboratory-simulated conditions. The greater forward swing torques did not result in significantly different racket head velocity, possibly because there was a significantly shorter forward swing phase in match conditions. In particular, a clear peak of the elbow extension torque during the forward swing phase was the most characteristic pattern in the smashes under match conditions, for it was 160% greater than laboratory-simulated conditions. These results supported our hypothesis that racket-arm kinematic and kinetic characteristics of the smash under match conditions differ from those under laboratory-simulated conditions. Possible explanations include the time-pressure conditions of the competitive situation in a match, and the Hawthorne effect (Hudson et al., 1986), both of which alter performance between match conditions and laboratory-simulated conditions.

Kinematics and Kinetics of the High Velocity Tennis Serve

2002 ◽  
Vol 34 (5) ◽  
pp. 105 ◽  
Author(s):  
Glenn S. Fleisig ◽  
Rochelle Nicholls ◽  
Rafael F. Escamilla ◽  
Bruce Elliott
Keyword(s):  
High Velocity ◽  
Tennis Serve ◽  
Kinetics Of ◽  
Kinematics And Kinetics

scholarly journals Joint Torque and Mechanical Power of Lower Extremity and Its Relevance to Hamstring Strain during Sprint Running

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Yunjian Zhong ◽  
Weijie Fu ◽  
Shutao Wei ◽  
Qing Li ◽  
Yu Liu
Keyword(s):  
Lower Extremity ◽  
Stance Phase ◽  
Swing Phase ◽  
Joint Torque ◽  
Mechanical Power ◽  
Movement Direction ◽  
Joint Torques ◽  
Sprint Running ◽  
Lower Extremity Muscle ◽  
Muscle Groups

The aim of this study was to quantify the contributions of lower extremity joint torques and the mechanical power of lower extremity muscle groups to further elucidate the loadings on hamstring and the mechanics of its injury. Eight national-level male sprinters performed maximum-velocity sprint running on a synthetic track. The 3D kinematic data and ground reaction force (GRF) were collected synchronously. Intersegmental dynamics approach was used to analyze the lower extremity joint torques and power changes in the lower extremity joint muscle groups. During sprinting, the GRF during the stance phase and the motion-dependent torques (MDT) during the swing phase had a major effect on the lower extremity movements and muscle groups. Specifically, during the stance phase, torque produced and work performed by the hip and knee muscles were generally used to counteract the GRF. During the swing phase, the role of the muscle torque changed to mainly counteract the effect of MDT to control the movement direction of the lower extremity. Meanwhile, during the initial stance and late swing phases, the passive torques, namely, the ground reaction torques and MDT produced by the GRF and the inertial movement of the segments of the lower extremity, applied greater stress to the hamstring muscles.

A New Postural Force Production Index to Assess Propulsion Effectiveness During Handcycling

2013 ◽  
Vol 29 (6) ◽  
pp. 798-803 ◽  
Author(s):  
Julien Jacquier-Bret ◽  
Arnaud Faupin ◽  
Nasser Rezzoug ◽  
Philippe Gorce
Keyword(s):  
Force Production ◽  
Movement Analysis ◽  
Joint Torques ◽  
Production Index ◽  
Effective Force ◽  
Generation Capacity ◽  
Preliminary Study ◽  
Kinetics Of ◽  
Kinematics And Kinetics ◽  
Insight Into

The aim of this study was to propose a new index called Postural Force Production Index (PFPI) for evaluating the force production during handcycling. For a given posture, it assesses the force generation capacity in all Cartesian directions by linking the joint configuration to the effective force applied on the handgrips. Its purpose is to give insight into the force pattern of handcycling users, and could be used as ergonomic index. The PFPI is based on the force ellipsoid, which belongs to the class of manipulability indices and represents the overall force production capabilities at the hand in all Cartesian directions from unit joint torques. The kinematics and kinetics of the arm were recorded during a 1-min exercise test on a handcycle at 70 revolutions per minute performed by one paraplegic expert in handcycling. The PFPI values were compared with the Fraction Effective Force (FEF), which is classically associated with the effectiveness of force application. The results showed a correspondence in the propulsion cycle between FEF peaks and the most favorable postures to produce a force tangential to the crank rotation (PFPI). This preliminary study opens a promising way to study patterns of force production in the framework of handcycling movement analysis.

Biomechanical Comparison between Elite Female and Male Baseball Pitchers

2009 ◽  
Vol 25 (1) ◽  
pp. 22-31 ◽  
Author(s):  
Yungchien Chu ◽  
Glenn S. Fleisig ◽  
Kathy J. Simpson ◽  
James R. Andrews
Keyword(s):  
Angular Velocity ◽  
Knee Extension ◽  
Elbow Extension ◽  
Ball Release ◽  
Ball Velocity ◽  
Baseball Pitchers ◽  
Biomechanical Features ◽  
Biomechanical Comparison ◽  
Kinetics Of ◽  
Kinematics And Kinetics

The purpose of the current study was to identify the biomechanical features of elite female baseball pitching. Kinematics and kinetics of eleven elite female baseball pitchers were reported and compared with eleven elite male pitchers. Results suggested that females share many similarities with males in pitching kinematics, with a few significant differences. Specifically, at the instant of stride foot contact, a female pitcher had a shorter and more open stride and less separation between pelvis orientation and upper torso orientation. From foot contact to ball release, a female pitcher produced lower peak angular velocity for throwing elbow extension and stride knee extension. Ball velocity was lower for the female. Foot contact to ball release took more time for a female pitcher. Maximal proximal forces at the shoulder and elbow joints were less for a female pitcher.

scholarly journals Upper-Limb Isometric Force Feasible Set: Evaluation of Joint Torque-Based Models

Biomechanics ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 102-117
Author(s):  
Nasser Rezzoug ◽  
Vincent Hernandez ◽  
Philippe Gorce
Keyword(s):  
Upper Limb ◽  
Isometric Force ◽  
Joint Torque ◽  
Force Distribution ◽  
Prediction Errors ◽  
Feasible Set ◽  
Joint Torques ◽  
Motor Abilities ◽  
Capacity Evaluation ◽  
Measured Force

A force capacity evaluation for a given posture may provide better understanding of human motor abilities for applications in sport sciences, rehabilitation and ergonomics. From data on posture and maximum isometric joint torques, the upper-limb force feasible set of the hand was predicted by four models called force ellipsoid, scaled force ellipsoid, force polytope and scaled force polytope, which were compared with a measured force polytope. The volume, shape and force prediction errors were assessed. The scaled ellipsoid underestimated the maximal mean force, and the scaled polytope overestimated it. The scaled force ellipsoid underestimated the volume of the measured force distribution, whereas that of the scaled polytope was not significantly different from the measured distribution but exhibited larger variability. All the models characterized well the elongated shape of the measured force distribution. The angles between the main axes of the modelled ellipsoids and polytopes and that of the measured polytope were compared. The values ranged from 7.3° to 14.3°. Over the entire surface of the force ellipsoid, 39.7% of the points had prediction errors less than 50 N; 33.6% had errors between 50 and 100 N; and 26.8% had errors greater than 100N. For the force polytope, the percentages were 56.2%, 28.3% and 15.4%, respectively.

scholarly journals Kinematics and kinetics of the bench-press and bench-pull exercises in a strength-trained sporting population

2009 ◽  
Vol 8 (3) ◽  
pp. 245-254 ◽  
Author(s):  
Simon N. Pearson ◽  
John B. Cronin ◽  
Patria A. Hume ◽  
David Slyfield
Keyword(s):  
Bench Press ◽  
Kinetics Of ◽  
Kinematics And Kinetics

scholarly journals Joint torque and velocity optimization for a redundant leg of quadruped robot

2017 ◽  
Vol 14 (5) ◽  
pp. 172988141773189 ◽  
Author(s):  
Taihui Zhang ◽  
Honglei An ◽  
Hongxu Ma
Keyword(s):  
Angular Velocity ◽  
Sagittal Plane ◽  
Load Capacity ◽  
Optimization Criterion ◽  
Quadruped Robot ◽  
Joint Torque ◽  
Quadratic Program ◽  
Hydraulic Actuator ◽  
Joint Torques ◽  
Physical Limitations

Hydraulic actuated quadruped robot similar to BigDog has two primary performance requirements, load capacity and walking speed, so that it is necessary to balance joint torque and joint velocity when designing the dimension of single leg and controlling its motion. On the one hand, because there are three joints per leg on sagittal plane, it is necessary to firstly optimize the distribution of torque and angular velocity of every joint on the basis of their different requirements. On the other hand, because the performance of hydraulic actuator is limited, it is significant to keep the joint torque and angular velocity in actuator physical limitations. Therefore, it is essential to balance the joint torque and angular velocity which have negative correlation under the condition of constant power of the hydraulic actuator. The main purpose of this article is to optimize the distribution of joint torques and velocity of a redundant single leg with joint physical limitations. Firstly, a modified optimization criterion combining joint torques with angular velocity that takes both support phase and flight phase into account is proposed, and then the modified optimization criterion is converted into a normal quadratic programming problem. A kind of recurrent neural network is used to solve the quadratic program problem. This method avoids tremendous matrix inversion and fits for time-varying system. The achieved optimized distribution of joint torques and velocity is useful for aiding mechanical design and the following motion control. Simulation results presented in this article confirm the efficiency of this optimization algorithm.

Physics-Based Seated Posture Prediction for Pregnant Women and Validation Considering Ground and Seat Pan Contacts

2012 ◽  
Vol 134 (7) ◽  
Author(s):  
Bradley Howard ◽  
Aimee Cloutier ◽  
Jingzhou (James) Yang
Keyword(s):  
Pregnant Women ◽  
Objective Function ◽  
Linear Regression Analysis ◽  
Joint Torque ◽  
Joint Torques ◽  
Design Variables ◽  
Optimization Formulation ◽  
Posture Prediction ◽  
Seated Posture ◽  
End Effectors

An understanding of human seated posture is important across many fields of scientific research. Certain demographics, such as pregnant women, have special postural limitations that need to be considered. Physics-based posture prediction is a tool in which seated postures can be quickly and thoroughly analyzed, as long the predicted postures are realistic. This paper proposes and validates an optimization formulation to predict seated posture for pregnant women considering ground and seat pan contacts. For the optimization formulation, the design variables are joint angles (posture); the cost function is dependent on joint torques. Constraints include joint limits, joint torque limits, the distances from the end-effectors to target points, and self-collision avoidance constraints. Three different joint torque cost functions have been investigated to account for the special postural characteristics of pregnant women and consider the support reaction forces (SRFs) associated with seated posture. Postures are predicted for three different reaching tasks in common reaching directions using each of the objective function formulations. The predicted postures are validated against experimental postures obtained using motion capture. A linear regression analysis was used to evaluate the validity of the predicted postures and was the criteria for comparison between the different objective functions. A 56 degree of freedom model was used for the posture prediction. Use of the objective function minimizing the maximum normalized joint torque provided an R2 value of 0.828, proving superior to either of two alternative functions.

A biomechanical comparison of different baseball batting training methods

2021 ◽  
pp. 174795412110362
Author(s):  
Wei-Han Chen ◽  
Yu-Cheng Chiu ◽  
Chiang Liu ◽  
Ming-Sheng Chan ◽  
Nicholas J Fiolo ◽  
...  
Keyword(s):  
Peak Velocity ◽  
Swing Phase ◽  
Training Methods ◽  
Trunk Rotation ◽  
Elbow Extension ◽  
Kinematic Parameters ◽  
Baseball Players ◽  
Training Plan ◽  
Biomechanical Comparison ◽  
Movement Differences

This study compared the kinematic parameters of swing mechanics under toss batting (TB), motor imagery (MI), video projection (VP), and virtual reality (VR) conditions during baseball batting. Nine college baseball players performed three swings to hit a tossed ball under TB conditions or a virtual ball under MI, VP, and VR conditions. The results revealed that upper trunk backward rotation was smaller in the loading phase under the VP and VR conditions than under the TB and MI conditions and lower under VR than under the VP condition ( p < 0.05) except at the load event. Pelvic backward rotation was smaller under the VR condition than under the TB, MI, and VP conditions ( p < 0.05). In the swing phase, TB demonstrated higher peak velocity at the head of the bat, lead elbow extension, and pelvis and upper trunk rotation than did MI, VP, and VR, whereas VP also demonstrated higher peak velocity in pelvic forward rotation than did VR ( p < 0.05). In summary, VR demonstrates a more realistic response in the loading phase and reduced pelvic backward rotation but lower movement velocities. Coaches should pay attention to movement differences between swing conditions when arranging a swing training plan.

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