Subject-specific computer simulation model for determining elbow loading in one-handed tennis backhand groundstrokes

A subject-specific angle-driven computer model of a tennis player, combined with a forward dynamics, equipment-specific computer model of tennis ball-racket impacts, was developed to determine the effect of ball-racket impacts on loading at the elbow for one-handed backhand groundstrokes. Matching subject-specific computer simulations of a typical topspin/slice one-handed backhand groundstroke performed by an elite tennis player were done with root mean square differences between performance and matching simulations of < 0.5 degrees over a 50 ms period starting from ball impact. Simulation results suggest that for similar ball-racket impact conditions, the difference in elbow loading for a topspin and slice one-handed backhand groundstroke is relatively small. In this study, the relatively small differences in elbow loading may be due to comparable angle-time histories at the wrist and elbow joints with the major kinematic differences occurring at the shoulder. Using a subject-specific angle-driven computer model combined with a forward dynamics, equipment-specific computer model of tennis ball-racket impacts allows peak internal loading, net impulse, and shock due to ball-racket impact to be calculated which would not otherwise be possible without impractical invasive techniques. This study provides a basis for further investigation of the factors that may increase elbow loading during tennis strokes.     

Coaching competency and satisfaction with the coach: a multi-level structural equation model

The purpose of this initial predictive validity study was to determine the ability of measures derived from the Athletes' Perceptions of Coaching Competency Scale II?-?High School Teams (APCCS II-HST) to predict satisfaction with the head coach. Specification of the statistical model was informed by the mediational model of coach-athlete interactions. The technical quality of the satisfaction measure was evaluated before testing the predictive validity of the coaching competency measures. Data were collected from athletes of seven sports. Athlete observations (N?=?748) were clustered within teams (G?=?74). Multi-group confirmatory factor analyses (CFA) provided evidence for factorial invariance of a reduced version of the satisfaction measure by athlete gender. Multi-level CFA provided evidence of model-data consistency for a reduced version of the satisfaction measure. Multi-level structural equation modelling provided evidence for the ability of latent coaching competency to positively predict latent satisfaction at both the athlete level (technique competency and motivation competency) and the team level (coaching competency) and for close model-data fit. Implications of this study include: that the APCCS II-HST should be viewed as a replacement for the Coaching Competency Scale when the intended population is appropriate; a preliminary multi-level measurement model for satisfaction with one's coach that should be considered as a potential starting point in subsequent studies; and empirical support for a key relationship proposed in the mediational model of coach-athlete interactions.     

The long-term athlete development model: physiological evidence and application

Within the UK, the "Long Term Athlete Development" (LTAD) model has been proposed by a variety of national governing bodies to offer a first step to considering the approach to talent development. The model, which is primarily a physiological perspective, presents an advancement of understanding of developing athletic potential alongside biological growth. It focuses on training to optimize performance longitudinally, and considers sensitive developmental periods known as "windows of opportunity". However, it appears that there are a number of problems with this theoretical model that are not necessarily transparent to coaches. Principally, the model is only one-dimensional, there is a lack of empirical evidence upon which the model is based, and interpretations of the model are restricted because the data on which it is based rely on questionable assumptions and erroneous methodologies. Fundamentally, this is a generic model rather than an individualized plan for athletes. It is crucial that the LTAD model is seen as a "work in progress" and the challenge, particularly for paediatric exercise scientists, is to question, test, and revise the model. It is unlikely that this can be accomplished using classical experimental research methodology but this should not deter practitioners from acquiring valid and reliable evidence.     

Introducing e-portfolios to pre-service teachers as tools for reflection and growth: lessons learnt

E-portfolios are being introduced into initial teacher education programmes internationally to help pre-service teachers build records of their learning journeys and develop into reflective practitioners; to allow them to assemble collections of evidence of their achievements against graduate standards, which can function as digital CVs; and to facilitate the seeding of personal learning networks that will support lifelong learning after graduation. Despite certain tensions between these aims, the potential benefits of e-portfolios make them an increasingly popular choice in teacher education. In this article, we discuss the introduction of Wi-Fi-based e-portfolios into a Master of Teaching programme at an Australian university. These served primarily as developmental e-portfolios, or personal learning environments (PLEs), and were designed to place particular emphasis on reflective practice. We describe how the e-portfolios were perceived and used by pre-service teachers in the first year of their implementation, and indicate the challenges and limitations encountered. Lessons learnt from the implementation are outlined and recommendations are proposed.     

A dialogue on dialectics

The following comments are intended as a constructive critique of the questions posed by Lima, Osterman and Rezende. The issues raised by the authors advocate for a return in research and teaching to the impetus of dialectical materialist approaches in the originators of the sociocultural school, including Vygotsky. The focus of this response is directed toward the need to historicize dialectics itself, as a tradition, method and approach. The relation between dialectics and materialist critique requires a critical scrutiny that also provides pedagogical spaces and temporalities for an entwining of dialectical practices with dialogic interchange. The intent of the following comments is to engage with the authors in shaping a materialist critique of some of the ways through which the sociocultural school and ‘Vygotskyian inspired practices have been domesticated within the neoliberal university.     

Becoming More Reflective about the Role of Design in Communication

Robert Craig's constitutive meta-model of communication reminds us that while communication scholarship may feel like discovery of communication's natural properties, it is also often (if not always) on a path to invention of new possibilities and reconstitution. The constitutive meta-model suggests that every theory of communication is also a design language for communication, and that design itself may be a path to theory development. Design inquiry can be conducted in all subdisciplines of communication, incorporating and contributing to widely disparate communication theories. Design work itself takes many forms, producing artifacts as diverse as individual messages, persuasive campaigns, interaction protocols, large-scale participation frameworks for public decision-making, and more. This special issue explores design scholarship in the field of communication, with five original essays representing different subfields and different theoretical approaches. In this introduction, we argue that design work is more than application of theory; design itself is a theory-building enterprise. It is a distinct form of inquiry that builds new knowledge, complementary to, but different in kind from, empirical and critical scholarship.