Sport-specific musculoskeletal growth and postural control in female artistic gymnasts: a 12 month cohort study

Abstract

Female gymnasts have been evidenced to experience sport-specific growth, of which broad shoulders and narrow hips are common characteristics. In addition to being a central component of handstand performance, postural control mechanisms, including whole-body and lumbo-pelvic stability, have been identified as risk factors for overuse spinal pathology. The study aimed to develop a fundamental understanding of musculoskeletal growth and postural control responses of female artistic gymnasts in order to extend longitudinal insights into overuse spinal pathology risk. Whole-body anthropometric measures were collected for 12 competitive female gymnasts (age at recruitment: nine to 15 years) at three time points across a 12 month period. Musculoskeletal growth was partially defined as the rate of bicristal-to-biacromial breadth ratio development, and informed shoulder- and pelvis-dominant growth sub-groups. Kinematic and kinetic indicators of postural control were determined for a total of 700 handstand trials. The shoulder-dominant (gymnastics-specific) growth group was found to have significantly greater biomechanical risk for general stability (p < 0.001) than the pelvis-dominant group. Significantly greater lumbo-pelvic risk was demonstrated for the pelvis-dominant group (p < 0.001). Extended idiosyncratic examination of proportional sport-specific growth measures alongside multi-faceted risk monitoring was advocated for the effective development of future overuse pathology prevention protocols.     

A non-parametric topical relevance model

An information retrieval (IR) system can often fail to retrieve relevant documents due to the incomplete specification of information need in the user’s query. Pseudo-relevance feedback (PRF) aims to improve IR effectiveness by exploiting potentially relevant aspects of the information need present in the documents retrieved in an initial search. Standard PRF approaches utilize the information contained in these top ranked documents from the initial search with the assumption that documents as a whole are relevant to the information need. However, in practice, documents are often multi-topical where only a portion of the documents may be relevant to the query. In this situation, exploitation of the topical composition of the top ranked documents, estimated with statistical topic modeling based approaches, can potentially be a useful cue to improve PRF effectiveness. The key idea behind our PRF method is to use the term-topic and the document-topic distributions obtained from topic modeling over the set of top ranked documents to re-rank the initially retrieved documents. The objective is to improve the ranks of documents that are primarily composed of the relevant topics expressed in the information need of the query. Our RF model can further be improved by making use of non-parametric topic modeling, where the number of topics can grow according to the document contents, thus giving the RF model the capability to adjust the number of topics based on the content of the top ranked documents. We empirically validate our topic model based RF approach on two document collections of diverse length and topical composition characteristics: (1) ad-hoc retrieval using the TREC 6-8 and the TREC Robust ’04 dataset, and (2) tweet retrieval using the TREC Microblog ’11 dataset. Results indicate that our proposed approach increases MAP by up to 9% in comparison to the results obtained with an LDA based language model (for initial retrieval) coupled with the relevance model (for feedback). Moreover, the non-parametric version of our proposed approach is shown to be more effective than its parametric counterpart due to its advantage of adapting the number of topics, improving results by up to 5.6% of MAP compared to the parametric version.     

Education research and policy making in higher education: the case of Dearing

In establishing a National Committee of Inquiry into Higher Education in the United Kingdom (the Dearing Committee), the Government expected short-term problems and long-term developments to be examined in less than half the average time taken by previous inquiries. Conscious of the intellectual authority of its predecessor, the Robbins Committee, the Dearing inquiry commissioned a large number of research and analytical studies to inform its deliberations. The ways that research and other forms of evidence were collected and considered by the inquiry are discussed in relation to four themes: the context and conditions for the inquiry; the nature of the work commissioned; the treatment of public evidence and the use of research to inform key recommendations; and what the episode disclosed about the relationship between education research and policy-making in higher education. In the course of this commentary, it is suggested that the uneven engagement with research and academic literatures in the Dearing inquiry was not simply a function of its terms and conditions of existence, but reflected more general features of the contemporary research base and policy environment in higher education.     

Do dynamic work instructions provide an advantage over static instructions in a small scale assembly task?

Recent studies exploring the effects of instructional animations on learning compared to static graphics have yielded mixed results. Few studies have explored their effectiveness in portraying procedural-motor information. Opportunities exist within an applied (manufacturing) context for instructional animations to be used to facilitate build performance on an assembly line. The present study compares build time performance across successive builds when using animation, static diagrams or text instructions to convey an assembly sequence for a handheld device. Although an immediate facilitating effect of animation was found, yielding a significantly faster build time for Build 1, this advantage had disappeared by Build 3.     

Differences in practitioners’ understanding of play and how this influences pedagogy and children’s perceptions of play

This paper presents research that examines the links between practitioners’ understanding of play and its relationship to learning, their pedagogic interactions with children and children’s own perceptions of their play. Previous research has shown a mismatch between practitioners’ understanding of play and their practice. This research identifies how differences in understanding of play, especially the role of the adult, by practitioners in two unrelated settings are associated with variation in pedagogic interactions emphasising choice and control. Furthermore, it is argued that these differences are reflected in differences in children’s use of the cue of adult presence as a defining feature of play and not-play activities.     

Lower limb joint kinetics and ankle joint stiffness in the sprint start push-off

Sprint push-off technique is fundamental to sprint performance and joint stiffness has been identified as a performance-related variable during dynamic movements. However, joint stiffness for the push-off and its relationship with performance (times and velocities) has not been reported. The aim of this study was to quantify and explain lower limb net joint moments and mechanical powers, and ankle stiffness during the first stance phase of the push-off. One elite sprinter performed 10 maximal sprint starts. An automatic motion analysis system (CODA, 200 Hz) with synchronized force plates (Kistler, 1000 Hz) collected kinematic profiles at the hip, knee, and ankle and ground reaction forces, providing input for inverse dynamics analyses. The lower-limb joints predominately extended and revealed a proximal-to-distal sequential pattern of maximal extensor angular velocity and positive power production. Pearson correlations revealed relationships (P < 0.05) between ankle stiffness (5.93 ± 0.75 N x m x deg(-1)) and selected performance variables. Relationships between negative power phase ankle stiffness and horizontal (r = -0.79) and vertical (r = 0.74) centre of mass velocities were opposite in direction to the positive power phase ankle stiffness (horizontal: r = 0.85; vertical: r = -0.54). Thus ankle stiffness may affect the goals of the sprint push-off in different ways, depending on the phase of stance considered.