The kinematic differences between accurate and inaccurate squash forehand drives for athletes of different skill levels     

Benjamin K. Williams  Ross H. Sanders  Joong Hyun Ryu  Philip Graham-Smith  Peter J. Sinclair 《Journal of sports sciences》2020,38(10):1115-1123

ABSTRACT

To maintain the accuracy of squash shots under varying conditions, such as the oncoming ball’s velocity and trajectory, players must adjust their technique. Although differences in technique between skilled and less-skilled players have been studied, it is not yet understood how players vary their technique in a functional manner to maintain accuracy under varying conditions. This study compared 3-dimensional joint and racket kinematics and their variability between accurate and inaccurate squash forehand drives of 9 highly skilled and 9 less-skilled male athletes. During inaccurate shots, less-skilled players hit the ball with a more open racket, demonstrating a difference in this task-relevant parameter. No joint kinematic differences were found for accuracy for either group. Coordinated joint rotations at the elbow and wrist both displayed a “zeroing-in” effect, whereby movement variability was reduced from the initiation of propulsive joint rotation to a higher consistency at ball-impact; potentially highlighting the “functionality” of the variability prior to the impact that enabled consistent task-relevant parameters (racket orientation and velocity) under varying conditions. Further, highly skilled players demonstrated greater consistency of task-relevant parameters at impact than less-skilled players. These findings highlight the superior ability of highly skilled players to adjust their technique to achieve consistent task-relevant parameters and a successful shot.  相似文献   

Engaging mothers with substance use issues and their children in early intervention: Understanding use of service and outcomes     

《Child abuse & neglect》2018

Mothers who use substances need integrated, multi-sectoral intervention services to support substance use discontinuation. We explored mothers’ service use at Breaking the Cycle, an early intervention and prevention program for pregnant and parenting women and their young children in Toronto, Canada. We conducted retrospective analyses of families’ service records and client charts (N = 160). Aims were to 1) describe women’s use of service, 2) examine how early engagement of pregnant women related to postnatal service use, and 3) examine the circumstances in which women ended their service relationship with Breaking the Cycle. Specifically, we examined circumstances at service ending relating to women’s service goals; custody status with children; and global substance-use, parent-child relationship, and child development outcomes. We found that these vulnerable women were actively engaged in many services and for a long duration, early engagement was associated with greater service use, and greater service use was associated with more positive circumstances upon ending service. Results provide support for a relational approach to service that promotes not only the relationship between mother and child, and mother and service provider, but also highlights relationships among staff, between staff and management, and between community partners as integral to effective service delivery. Integrating positive relationships at all levels is critical to support vulnerable families with complex needs.  相似文献   

商业模式动态演化机制：基于互联网业的多案例内容分析          下载免费PDF全文

张新香  胡立君 《科研管理》2018,39(3):110-121

本文根基商业模式内涵，构建商业模式结构模型，依据发展历程收集5家代表案例企业时间序列新闻文献和数据资料，运用内容分析法结构化分析文献资料，提炼互联网业商业模式动态演化规律和演化路径。研究显示：互联网业商业模式中，价值定义、价值实现、价值创造与传递三大构件的主导地位依次更替，对应呈现出客户价值实现、企业价值实现和网络价值实现的纵向三阶段演化模型，三阶段模型在时间跨度和运营绩效上与企业生命周期的创业期、发展期和成熟期很好吻合，商业模式的三大构件同样呈现出动态演化特征。本研究试图打开商业模式的组成结构黑箱，将商业模式的设计理论从静态视角升级到动态层面，为互联网业的发展给出可行的实践参考。  相似文献   

基于熵值-主成分分析法的天津市低碳经济发展水平评价   总被引：1，自引：0，他引：1  

史学飞 《科技管理研究》2018,(3)

针对低碳经济发展水平评价中存在的问题,将主成分分析法与熵值法结合,建立低碳经济评价模型,分析天津市2000—2015年低碳经济的发展状况。实证结果表明,低碳环境水平、低碳产业水平和居民生活水平是天津市低碳经济发展水平的主要影响因素。依据实证分析结果,从优化低碳市场环境、调整产业结构、倡导低碳生活、鼓励低碳出行四方面提出有利于天津市发展低碳经济的对策和建议。  相似文献   

Professionalising teaching: a corpus-based approach to the professional development of teachers in Singapore     

Peter Teo 《Cambridge Journal of Education》2018,48(3):279-300

This study explores the use of a corpus of classroom discourse data (Singapore Corpus of Research in Education or SCoRE) to facilitate the professional development of English language (EL) teachers in Singapore. A survey was first conducted to probe the knowledge base and belief system of EL teachers in three key domains: epistemology, pedagogy, and discourse. This was followed by a discourse analysis of the SCoRE corpus to mine resources that could address the specific professional needs of teachers identified through the survey. Survey findings suggest that EL teachers in Singapore are less secure in epistemology than pedagogy or discourse-related issues. The efficacy of using corpus-based materials to help teachers reflect on and develop their professional competencies was tested through a workshop. The paper concludes with a discussion of the implications of using authentic and situated corpus resources to facilitate teachers’ reflective practice and professional development.  相似文献   

Emotion regulation and motor performance: an integrated review and proposal of the Temporal Influence Model of Emotion Regulation (TIMER)     

Garrett F. Beatty  Christopher M. Janelle 《International review of sport and exercise psychology》2020,13(1):266-296

ABSTRACT

Adaptive regulation of emotions is imperative for successful sport performance. However, the lion’s share of mainstream emotion regulation (ER) literature is founded on perspectives prioritising mental health, not performance. Consequently, ER strategies are predominantly classified as adaptive or maladaptive based on effectiveness in achieving targeted mental health outcomes. These conventional mental health classifications can catalyse misapplication of ER strategies within sport and other motor performance contexts when (1) ER motives are instrumentally directed towards performance enhancement and (2) Minimal consideration is given to the consequences of ER on the coordination and execution of motor actions. Herein, we review the current state of relevant ER research within and outside of sport contexts. We also present a novel conceptual framework, the Temporal Influence Model of Emotion Regulation (TIMER). TIMER proposes that ER strategies exert distinct, temporally dependent demands upon perceptual-cognitive and motoric resources. These unique regulatory profiles influence subsequent motor performance outcomes. Critically, the degree to which regulatory strategies are appropriate or ideal varies given environmental constraints along with performers’ affective and performance goals. The model includes testable hypotheses to guide theoretical and applied research in the domain of ER within sport and other motor performance contexts.  相似文献   

Effects of audiovisual stimuli on psychological and psychophysiological responses during exercise in adults with obesity     

Marcelo Bigliassi  João P. A. Greca  Vinícius Barreto-Silva  Priscila Chierotti  Arli R. de Oliveira  Leandro R. Altimari 《Journal of sports sciences》2019,37(5):525-536

The present experiment sought to further understanding of the effects of personalised audiovisual stimuli on psychological and psychophysiological responses during exercise in adults with obesity. Twenty-four participants (M_age = 28.3, SD = 5.5 years; M_BMI = 32.2, SD = 2.4) engaged in self-paced exercises on a recumbent cycle ergometer and three conditions (sensory stimulation [ST], sensory deprivation [DE], and control [CO]) were administered. Perceptual (attentional focus and perceived exertion), affective (affective state and perceived activation), and psychophysiological (heart rate variability) parameters were monitored throughout the exercise bouts. A one-way repeated measures analysis of variance was used to compare self-reported and psychophysiological variables (main and interaction effects [5 Timepoints × 3 Conditions]). The results indicate that ST increased the use of dissociative thoughts throughout the exercise session (η_p² = .19), ameliorated fatigue-related symptoms (η_p² = .15) and elicited more positive affective responses (η_p² = .12) than CO and DE. Accordingly, personally-compiled videos are highly effective in ameliorating exertional responses and enhancing affective valence during self-paced exercise in adults with obesity. Audiovisual stimuli could be used during the most critical periods of the exercise regimen (e.g., first training sessions) when individuals with obesity are more likely to focus on fatigue-related sensations.  相似文献   

The association between fundamental athletic movements and physical fitness in elite junior Australian footballers     

Carl T. Woods  Ian McKeown  Justin Keogh  Sam Robertson 《Journal of sports sciences》2018,36(4):445-450

This study investigated the associations between fundamental athletic movement and physical fitness in junior Australian football (AF). Forty-four under 18 players performed a fundamental athletic movement assessment consisting of an overhead squat, double lunge, single leg Romanian deadlift and a push up. Movements were scored on three assessment criterions using a three-point scale. Additionally, participants performed five physical fitness tests commonly used for talent identification in AF. A Spearman’s nonparametric correlation matrix was built, with correlation coefficients being visualised using a circularly rendered correlogram. Score on the overhead squat was moderately positively associated with dynamic vertical jump height on left (r_s = 0.40; P ≤ 0.05) and right (r_s = 0.30; P ≤ 0.05) leg take-off, stationary vertical jump (r_s = 0.32; P ≤ 0.05) and negatively associated with 20-m sprint time (r_s = ?0.35; P ≤ 0.05). Score on the double lunge (left/right side) was moderately positively associated with the same physical fitness tests as well as score on the multistage fitness test. Results suggest that improvements in physical fitness qualities may occur through concurrent increases in fundamental athletic movement skill, namely the overhead squat and double lunge movements. These findings may assist with the identification and development of talent.  相似文献   

Differences in determinants of aerobic and muscle strengthening physical activity among college students: a reasoned action approach     

Paul Branscum  Grace Fairchild 《Journal of sports sciences》2019,37(1):90-99

  相似文献   

Teaching geographical databases at the engineering master level: learner-centred approach vs. teacher-centred approach     

Paolino Di Felice 《European Journal of Engineering Education》2018,43(5):757-770

This paper reports numbers about the author’s experience, spanning over 13 academic years, of teaching an introductory course about geographical databases to students of the Master degree in Information Engineering at L’Aquila University (Italy). The first eight editions of the course were delivered according to the teacher-centred approach, while the successive five editions have been delivered according to the student-centred approach. The large student engagement which characterised the last five editions of the course was vital in enhancing the student experience and encouraging deeper learning. Two preconditions that explain the results achieved in terms of classroom attendance and students’ performance.  相似文献