Yuxuan Zeng’s research while affiliated with Shanghai University of Sport and other places

Nittaku 40 + and DHS D40 + are new material seamed plastic table tennis balls, both of which are designated as official match balls and widely used. Due to the change of material and diameter of the new seamed plastic ball, its hardness and elasticity also change accordingly. The purpose of this study is to analyze the difference of the stroke effect between the two types of new material seamed plastic table tennis balls, taking Nittaku 40 + ball and DHS D40 + ball as an example. Table tennis players (N = 18) were randomly selected from the China Table Tennis College (M age = 15.16 ± 2.41; M height = 1.59 ± 0.32 m; M weight = 45.72 ± 5.17 kg). Each participant was all righthand shake-hands grip. The high-speed camera was used to measure ball speed and spin speed. Data normality was tested by using the Kolmogorov-Smirnov test. An Independent-Samples T test was conducted to assess the difference of the stroke effect between two types of new material seamed plastic table tennis balls (Nittaku 40 + and DHS D40+). Results showed that there was a significant difference between the two types of new material seamed plastic table tennis ball in the ball speed and spin speed during the backhand backspin loop stroke ( p = 0.041, p = 0.022, respectively), and the ball speed and spin speed of DHS D40 + were higher than that of Nittaku 40 + ball. Compared with the DHS D40 + ball, when hitting the Nittaku 40 + ball, players need to increase the swing distance and hit the ball with more strength to improve the ball speed and rotation speed.

Background: Nittaku 40+ and DHS D40+ are two different brands of new plastic balls, both of which are designated as official match balls and widely used in international events. Due to the change of material and diameter from traditional celluloid table tennis ball to new plastic ball, the hardness and elasticity of the new plastic ball also change accordingly. The purpose of this study is to analyze the difference of the dynamic elasticity between the two brands of new plastic ball, taking Nittaku 40+ ball and DHS D40+ ball as an example. Method: Self-made experiment was designed to generate different levels of initial speed of table tennis ball to test the dynamic elasticity characteristics of DHS D40+ and Nittaku 40+. A high-speed camera was used to collect the trajectory of ball falling and rebound after hitting the table during the experiment, and the Kinovea software was used to process the falling and rebound trajectory and calculate the average speed of falling and rebound process, then accordingly calculate the rebound speed decrement rate. Results: Results showed that the rebound speed and decrement rate of DHS D40+ and Nittaku 40+ both increased with the increase of falling speed, respectively. When falling at slow and medium speeds, there was no significant difference of dynamic elasticity between DHS D40+ and Nittaku 40+. When falling at high speed, there was a significant difference of dynamic elasticity between DHS D40+ and Nittaku 40+. Conclusion: Compared with the DHS D40+, the Nittaku 40+ has bigger hardness and brittleness, and the sphere structure is more uniform, featuring better dynamic elasticity stability and rebound height.

Background The technical and tactical diagnosis of table tennis is extremely important in the preparation for competition which is complicated by an apparent nonlinear relationship between athletes’ performance and their sports quality. The neural network model provides a high nonlinear dynamic processing ability and fitting accuracy that may assist in the diagnosis of table tennis players’ technical and tactical skill. The main purpose of this study was to establish a technical and tactical diagnosis model of table tennis matches based on a neural network to analyze the influence of athletes’ techniques and tactics on the competition results. Methods A three-layer Back Propagation (BP) neural network model for table tennis match diagnosis were established. A Double Three-Phase evaluation method produced 30 indices that were closely related to winning table tennis matches. A data sample of 100 table tennis matches was used to establish the diagnostic model ( n = 70) and evaluate the predictive ability of the model ( n = 30). Results The technical and tactical diagnosis model of table tennis matches based on BP neural network had a high-level of prediction accuracy (up to 99.997%) and highly efficient in fitting ( R 2 = 0.99). Specifically, the technical and tactical diagnosis results indicated that the scoring rate of the fourth stroke of Harimoto had the greatest influence on the winning probability. Conclusion The technical and tactical diagnosis model of table tennis matches based on BP neural network was highly accurate and efficiently fit. It appears that the use of the model can calculate athletes’ technical and tactical indices and their influence on the probability of winning table tennis matches. This, in turn, can provide a valuable tool for formulating player’s targeted training plans.

Working women in Shanghai are a high-risk group of suffering work stress and burnout. Women have been found to be affected by work-family conflicts, which results in lower health-related quality of life (HRQoL), higher job stress, and burnout. This study evaluated the potential physical activity and counselling intervention effects on health outcomes of working women in Shanghai. Participants were randomly recruited from eight communities of Shanghai using the stratified cluster sampling method. A total of 121 female workers took part in this study, who were randomly divided into three groups: a control group and two intervention groups (individual-based and group-based intervention). The first intervention involved a moderate physical activity program and an individual based counselling intervention, while the second included the same physical activity program, but with a group counselling approach. Both interventions lasted 12 weeks. Subjective perceptions of work stress, burnout, and HRQoL were measured before and after the intervention. In the control group, the HRQoL value decreased after the intervention, with the mean value falling from 91.59 to 87.10, while there was no significant difference found between participants for stress (p = 0.752) and burnout (p = 0.622) before and after the intervention. After the intervention, the value of stress and burnout decreased, and the value of HRQoL increased in the two intervention groups. At the intervention's completion, there were significant differences compared between the two intervention groups and the control group separately regarding changes in burnout and HRQoL (all p = 0.000). For stress, the group-based intervention group exhibited a significant difference compared to the control group (p = 0.000), while the individual-based intervention group did not (p = 0.128). A Physical activity and counselling intervention delivered either in a group or individual format could reduce stress, burnout, and improve HRQoL of working women in Shanghai, and the group interventions were potentially more effective than those targeted at individuals.

The main purpose of this study was to explore the impact of the wrist joint movement on the stroke effect, especially that of the angular velocity and linear velocity on the ball speed and spin speed. Thirty-two young table tennis players were randomly selected from China Table Tennis College. The high-speed infrared motion capture system was used to collect the real-time data of the wrist joint movement during the stroke, and the high-speed camera was used to measure the spin speed. The influence of the wrist joint movement on the stroke effect was analysed. The results of this study showed that the linear velocity of the right wrist joint was positively correlated with ball speed (r = 0.283, p < 0.01) and spin speed (r = 0.162, p = 0.032). The angular velocity of the right wrist joint had a significant positive correlation with the ball speed (r = 0.251, p = 0.015) and spin speed (r = 0.391, p < 0.01). The results of this study further explained the mechanism of power transfer by the kinetic segment-chain, which provided a valuable reference for formulating targeted training plans for young table tennis players.

Background: The technical and tactical diagnosis of table tennis is extremely important for the preparation of matches, and there is a nonlinear relationship between athletes’ performance and their sports quality. As the neural network model has high nonlinear dynamic processing ability and has high fitting accuracy, the main purpose of this study was to establish a technical and tactical diagnosis model of table tennis matches based on a neural network to diagnose the influence of athletes’ techniques and tactics on the competition result. Methods: A three-layer back propagation neural network model for table tennis match diagnosis were established. The 30 technical and tactical analysis indexes that are closely related to winning a competition were selected based on the double three-phase evaluation method. And 100 table tennis matches were selected as data sample, of which 70 matches were taken as training sample to establish the diagnostic model, the other 30 matches were used to test the validity of the diagnostic model. Results: The technical and tactical diagnosis model of table tennis matches based on BP neural network had a high precision up to 99.997% and highly efficient in fitting (R2 = 0.99). It had a good ability to diagnose the technical and tactical abilities of table tennis players. The technical and tactical diagnosis results showed that the scoring rate of the fourth stroke of Harimoto had the greatest influence on the winning probability. Conclusion: The technical and tactical diagnosis model of table tennis matches based on BP neural network had a high precision and highly efficient in fitting. By using this model, the weights of the influence of athletes’ technical and tactical indexes on the winning probability of the competition can be calculated, which provides a valuable reference for formulating targeted training plans for players.

Background: An optimal stroke is essential for winning table tennis competition. The main purpose of this study was to examine the correlations between the stroke characteristics and the stroke effect. Methods: Forty-two young table tennis players were randomly selected from China Table Tennis College (M age= 14.21; M height= 1.57m; M weight= 46.05 kg, right-hand racket, shake-hands grip, no injuries in each joint of the body). The high-speed infrared motion capture system was used to collect the data of stroke characteristics, and the high-speed camera was used to measure the spin speed of the stroke. The influence of stroke characteristics on stroke effect was analyzed. Results: The time duration of backswing and forward motion were significantly correlated with ball speed (r=-0.403, P<0.01; r=-0.390, P<0.01, respectively) and spin speed (r=-0.244, P=0.027; r=-0.369, P<0.01, respectively). The ball speed was positively correlated with the linear velocity of right wrist joint (r=0.298, P<0.01), and the angular velocity of right elbow joint (r=0.219, P=0.013), right hip joint (r=0.427, P<0.01) and right ankle joint (r=0.443, P<0.01). The spin speed was positively correlated with the linear velocity of right wrist joint (r=0.238, P=0.031), and the angular velocity of right elbow joint (r=0.172, P=0.048) and right hip joint (r=0.277, P=0.012). The placement had a negative correlation with the angular velocity of right knee joint (r=-0.246, P=0.026). Conclusions: The time allocation of the three phases of backspin forehand stroke had an important correlation with stroke effect, especially the ball speed and spin speed. The movement of the right wrist joint and right ankle joint were mainly correlated with the ball speed of the stroke. The spin speed of the stroke was mainly correlated with the movement of the right wrist joint. The placement of the stroke was mainly correlated with the rotation of the right knee joint.

Background: A perfect stroke is essential for winning table tennis competition. A perfect stroke is closely related to reasonable stroke structure, which directly affects the stroke effect. The main purpose of this study was to examine the correlations between the structural characteristics of stroke and the stroke effect. Methods: Forty-two young table tennis players were randomly selected from China Table Tennis College (M age = 14.21 ± 2.13; M height = 1.57 ± 0.14 m; M weight = 46.05 ± 6.52 kg, right-hand racket, shake-hands grip, no injuries in each joint of the body). The high-speed infrared motion capture system was used to collect the data of stroke structural characteristics, and the high-speed camera was used to measure the spin speed of the stroke. The influence of striking structural characteristics on striking effect was examined. Results: The time duration of backswing and forward motion were significantly correlated with ball speed (r = -0.403, p < 0.01; r = -0.390, p < 0.01, respectively) and spin speed (r = -0.244, p = 0.027; r = -0.369, p < 0.01, respectively). The linear velocity of right wrist joint was positively correlated with ball speed (r = 0.298, p < 0.01) and spin speed (r = 0.238, p = 0.031). The angular velocity of right elbow joint and right hip joint were positively correlated with ball speed (r = 0.219, p = 0.013; r = 0.427, p < 0.01, respectively) and spin speed (r = 0.172, p = 0.048; r = 0.277, p = 0.012, respectively). The angular velocity of right knee joint had a significantly negative correlation with placement (r = -0.246, p = 0.026). The angular velocity of right ankle joint had a significantly positive correlation with the ball speed (r = 0.443, p < 0.01). Conclusions: The time allocation of the three phases of backspin forehand stroke had an important impact on stroke effect, especially the ball speed and spin speed. The ball speed of the stroke was mainly affected by the translation of the right wrist joint. The spin speed of the stroke was mainly affected by the translation of the right wrist joint. The placement of the stroke was mainly affected by the rotation of the right knee joint.