Motor variability in sports: A non-linear analysis of race walking

Abstract

This aim of this study was to analyse the nature of movement variability and to assess whether entropy measures may represent a valuable synthetic index of neuromuscular organization. The regularity of kinematic/kinetic time series during race walking, the changes in the structure of intra-individual variability over the test session, and the influence of athletic skill in (inter)national rank athletes were investigated. Motion analysis techniques were used. Sample entropy (SampEn) was adopted to examine fluctuations in lower limb angles and ground reaction forces. The regularity of both original and surrogate time series was assessed and compared, by estimating SampEn, to verify the presence of non-linear features in movement variability. SampEn was statistically lower in the original data than in surrogates. In contrast, the regularity of time series did not change significantly throughout the subsequent intra-individual repetitions. Hip and ankle joint angles and vertical ground reaction force manifested increased entropy for skilled athletes. Results suggest that race walking variability was not only the product of random noise but also contained information about the inherent propriety of the neuro-musculo-skeletal system. Furthermore, they provide some indications about neuromuscular control of the lower limb joints during race walking gait, and about the differences between more and less skilled individuals.     

The Validity of the Tritrac-R3D Activity Monitor for the Assessment of Physical Activity in Children

Abstract

The purpose of this study was to evaluate the validity of the Tritrac-R3D Activity Monitor, a new instrument designed to improve assessments of physical activity. Comparisons were made with a heart rate monitor and with a Caltrac Activity Monitor. Thirty-five children (ages 9–11 years) were monitored on 3 different school days with all 3 instruments. The Tritrac was moderately correlated with the heart rate monitor (r =.58) and highly correlated with the Caltrac monitor (r =.88). By taking advantage of the minute-by-minute timing capability of the Tritrac and the heart rate monitors, it was discovered, that the correlations between these instruments were highest during free play situations (lunch/recess, recess, after school) and were lower when activity was more limited (class time) or structured (physical education). The ability of the Tritrac to assess activity on a minute-by-minute basis may greatly enhance its overall utility.     

Teaching within a Curricular Zone of Safety: School Culture and the Situated Nature of Student Teachers' Pedagogical Content Knowledge

Abstract

The purpose of this paper is to continue the theoretical delineation of the nature of pedagogical content knowledge. Two student teachers were observed teaching an elementary games and high school sport unit and interviewed in depth about their lessons, biography, pedagogical content knowledge, and aspects of the school culture. Data were analyzed by constant comparison and analytic induction. Trustworthiness was established through member checks and triangulation. In the high school, both student teachers tried to use extending and refining tasks, as they had in the elementary school. But, when confronted with aspects of the high school culture, both retreated to a curricular zone of safety relying on application tasks. This zone, the defining aspect of their pedagogical content knowledge of teaching sports, emerged from and was constituted by the relations among goals, capabilities, teaching, inadequate pedagogical content knowledge, and aspects of the school culture. It is argued that situated and cultural orientations contribute to psychological orientations currently used to delineate pedagogical content knowledge. A curricular zone of safety is offered as a concept that helped account for the emergence and persistence of particular ways of knowing content.     

Physiological Effects of Deep Water Running following a Land-Based Training Program

Abstract

The purpose of this study was to examine differences in knowledge representation and problem solutions in expert and novice youth baseball players. Ninety-four players in two age divisions, 7–8 years of age and 9–10 years of age, were assigned to three levels of expertise: high; average; and low skilled. Each subject participated in an interview session to elicit knowledge representation and solutions to five different defensive game situations. Interviews were transcribed and analyzed for content, solution to the problem, errors in problem solution, and qualitative trends. The frequency of advanced solutions to each of the five situations were analyzed in separate chi-square tests for age and expertise. Differences among the levels of expertise were found for the accuracy of solutions to three complex situations. Age was significant for only one situation. Patterns of knowledge content accessed during advanced and less advanced responses indicated both experts and novices were in a beginning stage of developing baseball knowledge structures. Errors in problem solutions indicated children had difficulty monitoring critical conditions and making correct inferences. Players' and teammates' ability to execute baseball skills seemed to influence the content and structure of tactical knowledge accessed during problem solution.     

Child, Program, and Family Ecological Variables in Early Intervention

This study is based on a conceptual framework which emphasized the importance of viewing early intervention outcomes in relation to both program and nonprogram variables. Three broad classes of independent variables were included in the framework child, program, and family ecology. The unique and combined contributions of these three sets of variables to the prediction of three indices of intervention outcome was assessed through regression techniques. As much as 68% of the variance in children's post-intervention developmental age (DA2) was explained by the combined influence of all three classes of variables. All three classes of variables again contributed uniquely to the prediction of parental satisfaction with the intervention, explaining 45% of the variance. The three classes of variables explained 36% of the variance in children's rate of development during the intervention (RDI), although the contribution of the program class was very minimal. In addition to ascertaining the contributions of sets of variables, the importance of individual variables within sets was also examined. Results from both types of analysis underscored the important role of nonprogram variables in the determination of both child and parental outcomes. The implications of these findings for the design and evaluation of early intervention are discussed.     

The use of computers in K-12 schools in turkey

Through the determined efforts of MONE, more than one third of the existing 5,851 schools have at least one computer lab. It is clear that the number of computers in schools in Turkey will continue to increase.     

Project THREAD: Technology helping restructure educational access and delivery

This article describes Project THREAD (Technology Helping Restructure Educational Access and Delivery), an initiative funded by the U.S. Office of Education through its PT3 grant program. The project’s overarching goal is to prepare teachers to integrate modern technologies to fundamentally enhance teaching and learning in K-12 schools. Project initiatives include: (a) a series of in-service workshops for university faculty, administrators, field supervisors, and mentor teachers; (b) one-on-one follow-up support provided by project staff; (c) a minigrant program to support the development of technology-based learning activities for university courses; (d) expanded opportunities for students to apply technology in thier courses and field experiences; and (e) a redesign of selected courses that impact a large number of teacher candidates. The project’s evaluation is described, along with a discussion of outcomes and lessons learned. in recognition of the project’s scope and accomplishments thus far, the College of Education at the University of Nevada, Las Vegas (UNLV), was named the 2002 winner of the Best Practice Award for the Innovative Use of Technology by the American Association of Colleges for Teacher Education (AACTE).     

Disseminating the right information to the right audience: cultural determinants in the use (and misuse) of rankings

Rankings and league tables, or Report Cards (RCs), of Higher Education Institutions have become a global phenomenon. Their purpose, it is claimed, is to help “student-consumers” make informed decisions. Yet the degree to which RCs succeed in helping students in their college choice is disputed. Even though RCs are intended for all, which information is sought and how it is used may differ between potential students hailing from different social, economic and cultural backgrounds. In particular, RCs may neglect certain cultural determinants that influence students’ college choice behaviour. The article reviews the literature on the cultural determinants of college choice and especially the use of RCs in the ambit of cultural determinants. In the United States, possibly because of evident educational gaps between ethnic groups in society, the issue of cultural perceptions in college choice has been addressed, albeit scantly. In Europe, this field of study is virtually non-existent, despite increasing indications that second and third generation immigrants still lag behind in terms of higher education participation and graduation rates.