The kinematic differences between off-spin and leg-spin bowling in cricket     

Aaron J. Beach  René E. D. Ferdinands  Peter J. Sinclair 《Sports biomechanics / International Society of Biomechanics in Sports》2016,15(3):295-313

Spin bowling is generally coached using a standard technical framework, but this practice has not been based upon a comparative biomechanical analysis of leg-spin and off-spin bowling. This study analysed the three-dimensional (3D) kinematics of 23 off-spin and 20 leg-spin bowlers using a Cortex motion analysis system to identify how aspects of the respective techniques differed. A multivariate ANOVA found that certain data tended to validate some of the stated differences in the coaching literature. Off-spin bowlers had a significantly shorter stride length (p = 0.006) and spin rate (p = 0.001), but a greater release height than leg-spinners (p = 0.007). In addition, a number of other kinematic differences were identified that were not previously documented in coaching literature. These included a larger rear knee flexion (p = 0.007), faster approach speed (p < 0.001), and flexing elbow action during the arm acceleration compared with an extension action used by most of the off-spin bowlers. Off-spin and leg-spin bowlers also deviated from the standard coaching model for the shoulder alignment, front knee angle at release, and forearm mechanics. This study suggests that off-spin and leg-spin are distinct bowling techniques, supporting the development of two different coaching models in spin bowling.  相似文献   

Effect of repeat-sprint training in hypoxia on post-exercise interleukin-6 and F2-isoprostanes     

Paul S. R. Goods  Brian Dawson  Grant J. Landers  Christopher J. Gore  Kevin Croft  Peter Peeling 《European Journal of Sport Science》2016,16(8):1047-1054

This investigation examined the oxidative stress (F₂-Isoprostane; F₂-IsoP) and inflammatory (interleukin-6; IL-6) responses to repeat-sprint training in hypoxia (RSH). Ten trained male team sport athletes performed 3(sets)*9(repetitions)*5?s cycling sprints in simulated altitude (3000?m) and sea-level conditions. Mean and peak sprint power output (MPO and PPO) were recorded, and blood samples were collected pre-exercise, and again at 8 and 60?min post-exercise. Both MPO and PPO were significantly reduced in hypoxia (compared to sea-level) in the second (MPO: 855?±?89 vs. 739?±?95?W, p?=?.006; PPO: 1024?±?114 vs. 895?±?112?W, p?=?.010) and third (MPO: 819?±?105 vs. 686?±?83?W, p?=?.008; PPO: 985?±?125 vs. 834?±?99?W, p?=?.008) sets, respectively. IL-6 was significantly increased from pre- to 1?h post-exercise in both hypoxia (0.7?±?0.2 vs. 2.4?±?1.4?pg/mL, p?=?.004) and sea-level conditions (0.7?±?0.2 vs. 1.6?±?0.3?pg/mL, p?d?=?0.80) suggesting higher IL-6 levels of post-hypoxia. F₂-IsoP was significantly lower 1?h post-exercise in both the hypoxic (p?=?.005) and sea-level (p?=?.002) conditions, with no differences between trials. While hypoxia can impact on exercise intensity and may result in greater post-exercise inflammation, it appears to have little effect on oxidative stress. These results indicate that team sport organisations with ready access to hypoxic training facilities could confidently administer RSH without significantly increasing the post-exercise inflammatory or oxidative stress response.  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   

Education and social cohesion: developing a framework for education sector reform in Sri Lanka1     

Peter Colenso 《Compare》2005,35(4):411-428

There is increasing interest in understanding and describing the links between education and ‘social cohesion’. However, the theoretical and empirical base for understanding these links is limited. There is also a shortage of practical tools for education policy‐makers and planners, to help them assess the impact of policies and investments, and to plan for future reform. This paper describes the initial development of an analytical and planning framework for addressing education and social cohesion within the context of a sector‐wide approach to education reform in Sri Lanka. A brief literature review suggests three inter‐connected domains in which links between education and social cohesion might be usefully analysed, together with three working hypotheses: (i) political economy/governance: education affects social cohesion through transparency and participation in education policy formulation, planning and management; (ii) equity/equality of opportunity: education affects social cohesion through the distribution of education resources, opportunities and outcomes; (iii) teaching/learning: education affects social cohesion through the development of certain competencies in students. Drawing on this analytical framework, research conducted in Sri Lanka is used to identify a set of interventions to promote social cohesion, with corresponding baseline, process and outcome indicators as benchmarks for measuring the progress and impact of intended policy measures. This process is described within the context of a ‘sector‐wide approach’ to education reform, intended to bring together the activities of the government and external partners within a single comprehensive medium‐term planning and budgetary framework.  相似文献   

Knowledge acquisition by computerized audiovisual feedback     

Fischer  Peter Michael  Mandl  Heinz 《European Journal of Psychology of Education - EJPE》1988,3(2):217-233

The present article gives an outline of the state of art in computer assisted intervention by learning-concomitant differential feedback. Based on the spectrum of possible meanings and interpretations given to the concepts ‘interaction’ and ‘interactive’ this concept is elaborated and illustrated by prototypical theoretical approaches. Based on our own empirical findings arguments are given showing that sophisticated audiovisual interactive new technologies can properly be used even on the small machines available in schools if the content materials and the flow of control given to the learner are carefully designed and based on principles of cognitive science.

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The study of butterflies     

Peter Smetacek 《Resonance》2001,6(5):8-15

In this part of the series on butterflies, we look at the types of variations found within species as well as their causes.  相似文献   

Comment: Reasoning with conditionals     

Peter F. W. Preece 《科学教学研究杂志》1993,30(9):1209-1210

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Effects of writing instruction and assessment on functional composition performance     

Hans Kuhlemeier  Huub Van Den Bergh 《Assessing Writing》1997,4(2):203-223

In this study the relationships between writing instruction and functional composition performance were analyzed. The data were obtained in a national assessment on the language proficiency of students in the third year of Dutch secondary education (age ±15). Multivariate multilevel analysis showed that 10 out of 36 instructional characteristics were related to functional composition performance. The effective instructional characteristics included: instruction and exercises in writing functional texts, writing for a specific purpose, tailoring to a particular audience, global rating of writing products by the teacher, and frequent evaluation of Dutch language proficiency through teacher-made tests and written assignments. No effects were found for the rather popular subskill exercises on idiom, syntax, spelling and punctuation, and for pre-writing activities, text revisions and peer-review. Furthermore, the effect of instructional characteristics was often different on one task than on another. Finally, there was little differential effectiveness for different groups of students. If one instructional characteristic was more effective than the other, this was generally true, to an equal degree, for boys and girls and for promoted and non-promoted students.  相似文献   

Education and Development: from the age of innocence to the age of scepticism     

Hans N. Weiler 《比较教育学》1978,14(3):179-198

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Foreword     

Peter P. Muirhead 《ASHE Higher Education Report》1977,6(3):v-v

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