Kinematic Characteristics of Backhand Block in Table Tennis

Author(s):  
Yi Ren ◽  
Zhipei Huang ◽  
Yiming Guo ◽  
Jiankang Wu ◽  
Yingfei Sun
PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10841
Author(s):  
Yuqi He ◽  
Xiang Lyu ◽  
Dong Sun ◽  
Julien S. Baker ◽  
Yaodong Gu

Background Topspin is one of the most attacking stroke in table tennis sport. The aim of this research was to investigate the kinematic characteristics of the lower limb (driving leg) during topspin forehand loop in different playing level table tennis athletes. Methods Ten male table tennis athletes performed topspin forehand loop shots with maximal force to hit the ball that was played by a professional table tennis coach. The three-dimensional Vicon motion analysis system was used to capture the kinematic information. Results The key findings from this research indicate that there were no significant differences in motion time between elite athletes (EA) and medium athletes (MA) during the entire phase (P = 0.784). EA showed significantly less knee (P < 0.001) as well as hip (P < 0.001) flexion in the BS stage when contrasted to MA, with a significant larger ankle varus (P = 0.003) as well as eversion (P < 0.001) than MA in the BS and FS phase, respectively. EA displayed a significant larger angular changing rate of ankle dorsiflexion (P < 0.001) and varus (P < 0.001) in the BS stage with ankle plantar flexion as well as eversion during the FS stage, with a significant larger ankle internal rotation (P = 0.003) and external rotation (P < 0.001) than MA in the BS and FS phase, respectively. Furthermore, EA showed significantly larger ankle dorsiflexion (P = 0.001) as well as plantarflexion (P < 0.001) ROM in the BS and FS phase respectively compared with MA. Conclusion Ankle activities in the all plane displayed significant differences in kinematic characteristics between EA and MA. MA should pay attention to the function that ankle played in the kinetic chain, such as training the lower limb muscle rapid reaction ability to improve the energy transfer efficiency and capability of the kinetic chain.


2020 ◽  
Vol 7 (3) ◽  
pp. 23-28
Author(s):  
EZIZ SARVAN SHIRVAN ◽  

This paper discusses the kinematic characteristics of lapping process and the main parameters of the process. It was determined that the influencing degree of technological parameters to the forming surface and processes. It was projected the construction of the lapping head for processing of internal cylindrical surfaces, scheme of the lapping operation and graphic description of the forces influencing. The relationships between the axial, radial and tangential cutting forces and the effect of the combined force thereof are determined in order to ensure the necessary surface pressure. During the analysis geometric and mathematical relationships were obtained. The extracted analytical expressions can be realized by further experimental researches and can be used in engineering calculations of technological parameters of processing by lapping. Angular velocity, friction force, linear velocity, also the length of the tactile curve and the radius of the part can be considered the main kinematic and dynamic parameters of the process that the formation of the surface, also the course of the process depends on these parameters. Depending on the kinematic parameters, the wear nature of the tool changes and this changes the linear and angular velocities, which have a significant impact on the accuracy, quality and productivity of processing. When examining the technological capabilities of the process, the nature of the movement between the part and the grinding tool, also changes in cutting speed are often considered as a main factor. Analytical expressions were obtained to determine the main parameters of the process, taking into account the kinematic characteristics of the friction process. These expressions can be used in engineering calculations and allow to determine the optimal values of the processing mode. In order to obtain the required micrometric surface cleanliness and measurement accuracy, correlation relationships were established between the main parameters of the process, equations of the equilibrium system of shear forces were compiled and analytical expressions were obtained based on the analysis of kinematic and dynamic properties of the system.


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