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The application of advanced engineering to tennis racket design has influenced the nature of the sport. As a result, the International Tennis Federation has established rules to limit performance, with the aim of protecting the nature of the game. This paper illustrates how changes to the racket affect the player-racket system. The review integrates engineering and biomechanical issues related to tennis racket performance, covering the biomechanical characteristics of tennis strokes, tennis racket performance, the effect of racket parameters on ball rebound and biomechanical interactions. Racket properties influence the rebound of the ball. Ball rebound speed increases with frame stiffness and as string tension decreases. Reducing inter-string contacting forces increases rebound topspin. Historical trends and predictive modelling indicate swingweights of around 0.030–0.035 kg/m2 are best for high ball speed and accuracy. To fully understand the effect of their design changes, engineers should use impact conditions in their experiments, or models, which reflect those of actual tennis strokes. Sports engineers, therefore, benefit from working closely with biomechanists to ensure realistic impact conditions. 相似文献
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Qualitative biomechanical principles for application in coaching 总被引：1，自引：0，他引：1
Many aspects of human movements in sport can be readily understood by Newtonian rigid-body mechanics. Many of these laws and biomechanical principles, however, are counterintuitive to a lot of people. There are also several problems in the application of biomechanics to sports, so the application of biomechanics in the qualitative analysis of sport skills by many coaches has been limited. Biomechanics scholars have long been interested in developing principles that facilitate the qualitative application of biomechanics to improve movement performance and reduce the risk of injury. This paper summarizes the major North American efforts to establish a set of general biomechanical principles of movement, and illustrates how principles can be used to improve the application of biomechanics in the qualitative analysis of sport technique. A coach helping a player with a tennis serve is presented as an example. The standardization of terminology for biomechanical principles is proposed as an important first step in improving the application ofbiomechanics in sport. There is also a need for international cooperation and research on the effectiveness of applying biomechanical principles in the coaching of sport techniques. 相似文献
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Chow JW Knudson DV 《Sports biomechanics / International Society of Biomechanics in Sports》2011,10(3):219-233
A deterministic model is a modeling paradigm that determines the relationships between a movement outcome measure and the biomechanical factors that produce such a measure. This review provides an overview of the use of deterministic models in biomechanics research, a historical summary of this research, and an analysis of the advantages and disadvantages of using deterministic models. The deterministic model approach has been utilized in technique analysis over the last three decades, especially in swimming, athletics field events, and gymnastics. In addition to their applications in sports and exercise biomechanics, deterministic models have been applied successfully in research on selected motor skills. The advantage of the deterministic model approach is that it helps to avoid selecting performance or injury variables arbitrarily and to provide the necessary theoretical basis for examining the relative importance of various factors that influence the outcome of a movement task. Several disadvantages of deterministic models, such as the use of subjective measures for the performance outcome, were discussed. It is recommended that exercise and sports biomechanics scholars should consider using deterministic models to help identify meaningful dependent variables in their studies. 相似文献
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Cheryl Graczewski Joel Knudson Deborah J. Holtzman 《Journal of Education for Students Placed at Risk》2013,18(1):72-96
Literature on school reform has emphasized the need for principals to expand beyond their traditionally administrative role and become instructional leaders. This article examines the relationship between the practice of site-based instructional leadership and the professional development that teachers received in the context of a district-wide reform effort in San Diego City Schools. Using data from teacher surveys and school-based interviews, we find a connection between aspects of principal instructional leadership (coherent school-wide vision and leaders' engagement in instructional improvement) and selected research-based characteristics of effective teacher professional development (coherence and focus on content and curriculum). We conclude by addressing some of the tensions and limitations associated with a particular vision for site-based instructional leadership. 相似文献
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Smoothing to obtain accurate position and velocity data near impacts in sport biomechanics studies is complicated by the accelerations of impact, endpoint effects and the smoothing technique used. Wrist goniometric data with two levels of random noise added were used to examine three endpoint modelling conditions for obtaining accurate position and velocity data at impact in the tennis forehand. The common approach of smoothing through impact created distortions of the position signal up to 100 ms before impact and resulted in consistent underestimations (-3.2%) of wrist angle and angular velocity (-67.9%) at impact. New linear and polynomial extrapolation conditions smoothed with all techniques provided lower root mean squared errors than the smoothing-through-impact condition, with discrete wrist positions at impact within 1.1% of the criterion data. Both the new linear and polynomial conditions can be used to make more accurate angular position and velocity estimates for tennis impacts, whereas the smoothing-through-impact condition creates spurious decreases in speed before impact that in the past have been assumed to be aspects of skilful movement. 相似文献
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John Blackwell Duane Knudson 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(2):187-191
This study investigated the effect of the larger diameter (Type 3) tennis ball on performance and muscle activation in the serve. Sixteen male advanced tennis players performed serves using regular size and Type 3 tennis balls. Ball speed, surface electromyography, and serve accuracy were measured. There were no significant differences in mean initial serve speeds between balls, but accuracy was significantly greater (19.3%) with the Type 3 ball than with the regular ball. A consistent temporal sequence of muscle activation and significant differences in mean activation of different muscles were observed. However, ball type had no effect on mean arm muscle activation. These data, combined with a previous study, suggest that play with the larger ball is not likely to increase the risk of overuse injury, but serving accuracy may increase compared to play with the regular ball. 相似文献
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ChengTu Hsieh Duane Knudson 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(3):398-402
The aim of this study was to identify the student behaviours and characteristics that are related to learning biomechanical concepts. The Biomechanics Concept Inventory (BCI) was given to 53 kinesiology majors before and after an introductory biomechanics class together with a survey of student behaviours to determine factors that assisted in learning. Analysis of scores from 49 students showed significant (P < 0.001) improvement following instruction. Variables that significantly (P < 0.05) and uniquely correlated with improvement were grade point average (r = 0.46) and student interest in biomechanics (r = 0.41). Thirty-one percent of the variance in learning could be accounted for by these two variables, with no distinctive associations with student behaviours like course reading, hours studying, and credits earned in maths and physics. However, grade point average was significantly correlated with several student behaviour variables. Consequently, student learning of biomechanical concepts is likely a complex phenomenon with individual learning related to variables that interact with student interest and overall academic ability. 相似文献
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ChengTu Hsieh Melissa Mache Duane Knudson 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(1):108-119
Students' learning style preferences have been widely adapted into teaching and learning environments. The purpose of this study was to investigate the relationship between self-reported and assessed learning style preferences (visual, auditory, reading/writing, kinesthetic: VARK) on performance in different types of multiple-choice examinations (T1: text only format and T2: visual format) given in an introductory biomechanics class. Students who enrolled in three biomechanics classes at a state university were recruited to participate in the study. Ninety students (47 males and 43 females) completed a learning style survey and two types of examinations. Results showed that approximately half of the students were assessed and self-reported as kinesthetic for their preferred learning style. There was no significant difference in test performance between students who preferred visual and reading/writing learning styles (self-reported and assessed). These students demonstrated similar learning and comprehension of biomechanical concepts regardless of whether the test material was presented in their preferred sensory mode or not. Interestingly, female students' perceptions of their learning style preference may have a positive effect on the test results when the test is presented in their preferred format. 相似文献
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