Biomechanical loading of the hip during side jumps by soccer goalkeepers

Abstract

There is a risk of hip injury in dives to the side by soccer goalkeepers. In this study, we assessed hip loading in goalkeepers when performing such dives. The experiments were conducted in a laboratory setting using an in-ground force plate as well as on a grass surface when the athletes were equipped with force sensors. The forces acting on the hip were measured and high-speed video analysis was performed, allowing the investigation of the dive characteristics and techniques. The peak force values recorded in the laboratory setting ranged from 3 to 8 kN, which corresponded to 4.2–8.6 times body weight. The vertical impact velocities reached 3.25 m · s^?1. In the field experiments, a hip loading of 87–183 N · cm^?2 was determined. We found that goalkeepers who perform a rolling motion reduce their hip loading. The data provided by this study add to the biomechanics database and contribute to the establishment of injury criteria. Such information is necessary to develop and implement strategies to help prevent hip injuries.     

Hip adductor activations during run-to-cut manoeuvres in compression shorts: implications for return to sport after groin injury

Abstract

Athletes at high risk of groin strains in sports such as hockey and soccer often choose to wear shorts with directional compression to aid in prevention of or recovery from hip adductor strains. Large, eccentric contractions are known to result in or exacerbate strain injuries, but it is unknown if these shorts have a beneficial effect on hip adductor muscle activity. In this study, surface electromyography (EMG) of the adductor longus and ground reaction force (GRF) data were obtained simultaneously on 29 healthy individuals without previous history of serious injury while performing unanticipated 45° run-to-cut manoeuvres in a laboratory setting wearing shorts with non-directional compression (control, HeatGear, Under Armour, USA) or shorts with directional compression (directional, CoreShort PRO, Under Armour, USA), in random order. Average adductor activity in the stance leg was significantly lower in the directional condition than in the control condition during all parts of stance phase (all P < 0.042). From this preliminary analysis, wearing directional compression shorts appears to be associated with reduced stance limb hip adductor activity. Athletes seeking to reduce demand on the hip adductors as they approach full return to activities may benefit from the use of directional compression shorts.     

White Paper: functionality and efficacy of wrist protectors in snowboarding—towards a harmonized international standard

The wrist is the most frequently injured body region among snowboarders. Studies have shown that the risk of sustaining a wrist injury can be reduced by wearing wrist protection. Currently, there are a wide variety of wrist protection products for snowboarding on the market that offer a range of protective features. However, there are no minimum performance standards for snowboarding wrist protectors worldwide. The International Society for Skiing Safety convened a task force to develop a White Paper to evaluate the importance and necessity of a minimum performance for all wrist protectors used in snowboarding. The White Paper outlines the need for a general framework for a harmonized international standard and reviews the existing evidence. Therefore, this White Paper may serve as a common base for future discussions. The broader goal of developing and implementing such a standard is to reduce the incidence and the severity of wrist injuries in snowboarding without increasing the risk of adverse events, such as upper arm or shoulder injury. The European standard for inline skating wrist protectors (EN 14120) can serve as a starting point for efforts related to a standard for snowboard wrist protectors, but certain modifications to the standard would be required. It is hypothesized that implementation of a snowboarding wrist protector standard would result in fewer and less severe wrist injuries in the sport and could translate into more riding days for healthy snowboarders and significant health-care costs savings.     

The Concept of Tens and Hundreds in Students with Down Syndrome

ABSTRACT

We present an evaluation of the understanding that adolescents and adults with Down syndrome (DS) have of the decimal number system. The results of two studies are presented. The first was a case study with interviews of three adolescents and three adults with Down syndrome. Our results indicate that their conceptual understanding of the meaning of the tens and hundreds places is not as well developed as their ability to read, write and work with numbers of up to three digits. We also analyse the progress made by a 17- year-old student with Down syndrome after following a learning programme intended to improve her understanding of the tens place. To this end, we designed number tasks using four constructs: counting, grouping, partitioning and ordering. The student’s achievements in the counting construct were greater than in the others, exhibiting an understanding and use of the tens as a unit of counting to solve many of the number tasks proposed. Also evident was a progression in her understanding of the positional value. We observed differences in her success rate and variability in her responses depending on the method used in the tasks to represent the numbers.     

The Effect of Loans on the Persistence and Attainment of Community College Students

This study informs public policies regarding the use of subsidized loans as financial aid for community college students. Using logistic regression, it analyzes the National Center for Education Statistics’ Beginning Postsecondary Students (BPS 90/94) data to predict persistence to the second year of college and associate’s degree attainment over five years. During the period under study, loans did not contribute to higher persistence and attainment rates. Loans are observed to have a negative effect on persistence and no effect on degree attainment. Estimates of the interaction effects of borrowing and income status are insignificant but demonstrate the need for further testing. The findings are attributed to a combination of the high uncertainty of degree completion among community college students and the negative affective component of indebtedness. Earlier versions of this paper were presented at the American Education Finance Association Annual Meeting (Austin, Texas, March, 2000) and at the AIR Forum (Cincinnati, Ohio, May 2000). It has also appeared as a working paper of the Institute for Higher Education Law and Governance at the University of Houston, Texas (IHELG Monograph 01–07).This paper is based upon work supported by the Association for Institutional Research, the National Center for Education Statistics and the National Science Foundation under Association for Institutional Research Grant No. 99-128-0.     

Pedagogical content knowledge as reflected in teacher–student interactions: Analysis of two video cases

Despite the theorized centrality of pedagogical content knowledge (PCK) for teaching, we have little evidence of the relationship between PCK and students' learning and know relatively little about how to help teachers to develop PCK. This study is a preliminary attempt to address these gaps in our knowledge of PCK through exploration of two German physics teachers' classroom instruction in consecutive lessons on optics. We show how video analysis can be used to gather evidence for one aspect of teachers' PCK: their use of content knowledge in interactions with students. We identify three potentially important characteristics of this aspect of PCK: flexibility, richness, and learner‐centeredness. By contrasting teachers with high and low gains in student knowledge and interest, we explore potential mechanisms by which this aspect of PCK might affect student outcomes. Because German teacher preparation programs emphasize content more than pedagogical knowledge, these cases contribute to our understanding of the support that teachers with strong content knowledge may need in translating this knowledge into a form useful for teaching.Fachdidaktisches Wissen ist aus theoretischer Sicht besonders zentral für das Unterrichten. Aus empirischer Sicht gibt es bislang allerdings noch wenig Evidenz für den Einsatz fachdidaktischen Wissens während des Unterrichtens und seine Bedeutung für das Lernen von Schülerinnen und Schülern. Außerdem wissen wir wenig darüber, wie Lehrpersonen über die Zeit fachdidaktisches Wissen entwickeln. Diese Studie ist ein Versuch, diese Wissenslücken zum fachdidaktischen Wissen von Lehrpersonen zu bearbeiten. Dabei wird exemplarisch der Unterricht von zwei deutschen Physiklehrern in aufeinanderfolgenden Stunden zum Thema Optik untersucht. Die Studie zeigt wie Videoanalysen genutzt werden können, um Belege für einen Aspekt des fachdidaktischen Wissens der Lehrpersonen zu sammeln: Ihre Nutzung von inhaltlichem Wissen in der Interaktion mit den Schülerinnen und Schülern. In dieser Studie werden drei potentiell wichtige Charakteristika dieses Aspekts des fachdidaktischen Wissens identifiziert: Flexibilität, Reichhaltigkeit und Schülerorientierung. Durch die Gegenüberstellung von Lehrpersonen mit hohem und niedrigem Wissens‐ und Interessenzuwachs wurden potentielle Mechanismen untersucht, durch die dieser Aspekt des fachdidaktischen Wissens die Lernergebnisse von Schülerinnen und Schülern beeinflussen kann. Die Lehrerausbildung in Deutschland betont das inhaltliche Wissen stärker als das fachdidaktische Wissen. Die ausgewählten Fälle beschreiben, welche Unterstützung Lehrpersonen mit einem hohen fachlichen Wissen benötigen, um dieses Wissen so zu verändern, dass es für das Unterrichten genutzt werden kann. © 2012 Wiley Periodicals, Inc. J Res Sci Teach 49: 1211–1239, 2012     

Making the Case for Standards of Conduct in Clinical Training

The authors examined a proposed set of standards for the personal and professional conduct of counseling trainees. Eighty‐two counselor educators and supervisors from programs accredited by the Council for Accreditation of Counseling and Related Educational Programs ranked 55 behaviors divided across 3 categories (i.e., professional, interpersonal, and intrapersonal). Q‐sort methodology was used to collect the data, and the results provide a starting point for identifying criteria for gatekeeping practices.     

Collection Analysis When the Budget Decreases

This article begins with a discussion of the rationale behind an in-depth analysis of specific areas of a law library collection and a synopsis of selected past efforts and possible reasons for such an analysis. The majority of the article details the exact steps in the analysis process, as performed by the librarians at the William A. Wise Law Library at the University of Colorado Law School. The main purpose of the Wise Library's analysis was to identify materials that could most easily be cancelled if budget cuts warranted such actions. Finally, collection development considerations that may arise when deciding if and when to cut specific materials and alternative strategies that may be employed are discussed.     

Young children category learning: a training study

From an integrative approach, this work focuses on the role of conceptual mechanisms, such as comparison and conceptual-based inference, and sociopragmatic support in young children's taxonomic categorization. “Experiment 1” assessed whether 3-, 4-, and 6-year-old children succeed in detecting taxonomic relations on their own. A clear developmental trend was found: 6-year-olds succeeded, whereas 4- and 3-year-olds relied primarily on perceptually based categories. “Experiment 2” assessed if 3-year-olds are able to change their perceptual response into a taxonomic categorization as a function of the co-occurrence of contingent category information and feedback in an interactive process with an adult (experimenter). A pretest–posttest training study compared 3-year-olds' performance in four conditions: comparison, conceptual-based, information-only, and feedback-only. A perceptual–totaxonomic shift was found only in the comparison and conceptual-based training groups. Children who only received either category information or corrective feedback did not make such a shift. The results show that social interaction with supportive adults is a mechanism that drives conceptual understanding in early childhood.