A review of tennis racket performance parameters     

Tom Allen  Simon Choppin  Duane Knudson 《Sports Engineering》2016,19(1):1-11

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   

Active recovery of the finger flexors enhances intermittent handgrip performance in rock climbers     

Jiří Baláš  David Giles  Jan Kodejška  Michaela Panáčková  Simon Fryer 《European Journal of Sport Science》2016,16(7):764-772

This study aimed to (1) evaluate the effect of hand shaking during recovery phases of intermittent testing on the time–force characteristics of performance and muscle oxygenation, and (2) assess inter-individual variability in the time to achieve the target force during intermittent testing in rock climbers. Twenty-two participants undertook three finger flexor endurance tests at 60% of their maximal voluntary contraction until failure. Performances of a sustained contraction and two intermittent contractions, each with different recovery strategies, were analysed by time–force parameters and near-infrared spectroscopy. Recovery with shaking of the forearm beside the body led to a significantly greater intermittent test time (↑ 22%, P?P?P?相似文献   

Determining optimal cadence for an individual road cyclist from field data     

Robert Reed  Simon Adrian Jobson  Louis Passfield 《European Journal of Sport Science》2016,16(8):903-911

The cadence that maximises power output developed at the crank by an individual cyclist is conventionally determined using a laboratory test. The purpose of this study was two-fold: (i) to show that such a cadence, which we call the optimal cadence, can be determined using power output, heart-rate, and cadence measured in the field and (ii) to describe methodology to do so. For an individual cyclist's sessions, power output is related to cadence and the elicited heart-rate using a non-linear regression model. Optimal cadences are found for two riders (83 and 70 revolutions per minute, respectively); these cadences are similar to the riders’ preferred cadences (82–92?rpm and 65–75?rpm). Power output reduces by approximately 6% for cadences 20?rpm above or below optimum. Our methodology can be used by a rider to determine an optimal cadence without laboratory testing intervention: the rider will need to collect power output, heart-rate, and cadence measurements from training and racing sessions over an extended period (>6 months); ride at a range of cadences within those sessions; and calculate his/her optimal cadence using the methodology described or a software tool that implements it.  相似文献   

Effects of load mass carried in a backpack upon respiratory muscle fatigue     

Mark Faghy  Sam Blacker  Peter I. Brown 《European Journal of Sport Science》2016,16(8):1032-1038

Purpose: The purpose of this study was to investigate whether loads carried in a backpack, with a load mass ranging from 0 to 20?kg, causes respiratory muscle fatigue. Methods: Eight males performed four randomised load carriage (LC) trials comprising 60?min walking at 6.5?km?h^?1 wearing a backpack of either 0 (LC₀), 10 (LC₁₀), 15 (LC₁₅) or 20?kg (LC₂₀). Inspiratory (P_Imax) and expiratory (P_Emax) mouth pressures were assessed prior to and immediately following each trial. Pulmonary gas exchange, heart rate (HR), blood lactate and glucose concentration and perceptual responses were recorded during the first and final 60?s of each trial. Results: Group mean P_Imax and P_Emax were unchanged following 60-min load carriage in all conditions (p?>?.05). There was an increase over time in pulmonary gas exchange, HR and perceptions of effort relative to baseline measures during each trial (p?p?>?.05). Conclusions: These findings indicate that sub-maximal walking with no load or carrying 10, 15 or 20?kg in a backpack for up to 60?min does not cause respiratory muscle fatigue despite causing an increase in physiological, metabolic and perceptual parameters.  相似文献   

Research submission categories     

I. Diane Cooper 《Journal of the Medical Library Association》2016,104(2):98-99

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Degrees of value: comparing the contextual complexities of UK transnational education in Malaysia and Hong Kong     

I Lin Sin  Maggi W. H. Leung  Johanna L. Waters 《Compare》2019,49(1):132-148

This paper reveals the complex diversity that underpins ostensibly similar transnational education programmes (TNE), through a comparison of UK TNE in Malaysia and Hong Kong. It draws on data from two different yet cognate studies on the role of UK universities in delivering higher education in Asia. Some fine-grained and informative differences between the ways in which ‘value’ in TNE is constructed in different host contexts is revealed. The paper brings to light the ‘voices’ of TNE students and graduates, which are very seldom heard. The arguments adapt and extend the concepts of education as a positional good, and as cultural capital. For various instrumental, intrinsic and personal reasons the authors discuss in detail, UK TNE is more highly valued in Malaysia than in Hong Kong. The paper makes a wider contribution to knowledge on the changing landscape of international higher education and the impact on social and personal (dis)advantage.  相似文献   

Heroes of resiliency and reciprocity: teachers’ supporting role for reconceptualizing superhero play in early childhood settings     

Kathleen I. Harris 《Pastoral Care in Education》2016,34(4):202-217

Superhero play is a specialised form of fantasy play with considerable appeal to young children. During superhero play, children have opportunities to pretend and often to play different types of roles within a safe and caring environment. When guided appropriately in an early childhood classroom, superhero play gives young children opportunities to gain a sense of mastery and empowerment as well as developmentally appropriate benefits by improving language skills, problem-solving and cooperation with peers. By recognising and modelling the characteristics of resiliency and promoting kindness with peers during superhero play, teachers can encourage children to be kind and resilient heroes to classroom friends. As today’s classrooms increasingly include diverse members, it is important for young children to understand and appreciate the peers they play and learn with at school. The result may be a richer learning experience and may break down barriers that can produce unfairness, bullying and aggressive behaviours. This article explores the essence of superhero fantasy play along with its benefits for young children. In addition, the article examines the challenge of superhero play in classrooms for early childhood educators by exploring teachers’ roles in play. A new pedagogy for supporting superhero play is introduced, addressing spiritual and educational concerns by suggesting ways in which teachers can increase resiliency, encourage new friendships and build classroom community among peers during play and classroom activities.  相似文献   

Different Disciplines Require Different Motivations for Student Success     

Rosanna Breen  Roger Lindsay 《Research in higher education》2002,43(6):693-725

This article reports an investigation of undergraduate motivation to learn. A Likert-type rating scale measure of motivation incorporated the general motivational dimensions identified by previous investigators, as well as a systematic theoretical framework that is more novel, and attempts to acknowledge the role of discipline-specific factors in motivation to learn. The motivation questionnaire was evaluated by measuring its success in explaining the academic achievement of biology, history, computing, planning, anthropology, geology, food science and nutrition, and education students (n = 380) in standard university assessments. The findings reveal that student performance is better explained by within- than across-discipline indexes of motivation, probably because some types of motivation lead to success in some disciplines but failure in others. Furthermore, items based on the theoretical framework developed to underpin the questionnaire (which distinguishes outcome from process incentives) were also found to explain more variation in student performance than general motivation items. Some practical implications of the findings are considered.  相似文献   

National and international aspects of education     

I. L. Kandel 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1955,1(1):5-17

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The management of quality in the University of Ulster     

Roger Ellis 《Higher Education》1993,25(3):239-257

The setting of standards for teaching is identified as central to any system of quality assurance for teaching and learning. The paper describes a number of initiatives which have been taken at the University of Ulster to identify and develop quality in teaching. They include a project to identify teaching skills through consultation with expert teachers; the use of quality circles of staff and students to specify standards for teaching; the use of student feedback on teaching; the introduction of a distinguished teaching award; the assessment of teaching competence when staff are selected; the introduction of a unit-based in-service teacher training course; and the encouragement of self and peer evaluation using an appraisal schedule. Quality assurance for support services is considered and finally the University's initiatives are related to total quality management and BS 5750.  相似文献