Information-governing dynamics of attacker–defender interactions in youth rugby union

Abstract

Previous work on dynamics of interpersonal interactions in 1 vs. 1 sub-phases of basketball has identified changes in interpersonal distance between an attacker and defender as a potential control parameter for influencing organizational states of attacker–defender dyads. Other studies have reported the constraining effect of relative velocity between an attacker and defender in 1 vs. 1 dyads. To evaluate the relationship between these candidate control parameters, we compared the impact of both interpersonal distance and relative velocity on the pattern-forming dynamics of attacker–defender dyads in the sport of rugby union. Results revealed that when interpersonal distance achieved a critical value of less than 4 m, and relative velocity values increased or were maintained above 1 m · s^?1, a successful outcome (i.e. clean attempt) for an attacker was predicted. Alternatively, when values of relative velocity suddenly decreased below this threshold, at the same critical value of interpersonal distance, a successful outcome for the defender was predicted. Data demonstrated how the coupling of these two potential, nested control parameters moved the dyadic system to phase transitions, characterized as a try or a tackle. Observations suggested that relative velocity increased its influence on the organization of attacker–defender dyads in rugby union over time as spatial proximity to the try line increased.     

Improvement of cellular health indicators and muscle quality in older women with different resistance training volumes

ABSTRACT

The main purpose of this study was to compare the effects of resistance training (RT) performed with different training volumes on phase angle (PhA), body water components, and muscle quality (MQ) in untrained older adult women. A second purpose was to assess the relationship between PhA and MQ. Sixty-two older adult women (68.6 ± 5.0 years, 65.2 ± 13.3 kg, 156.1 ± 6.2 cm) were randomly assigned into one of the three groups: two training groups performed either 1 set (G1S) or 3 sets (G3S), or a control group (CG). Body water components and PhA were estimated by bioelectrical impedance (BIA). MQ was determined by dividing skeletal muscle mass estimated by dual-energy absorptiometry (DXA) by total muscle strength from three exercises. After the intervention period, both training groups demonstrated improvements (P < 0.05) when compared with CON for intracellular water, total body water, PhA, and MQ. These results suggest that RT can improve PhA, body water components, and MQ after 12 weeks of RT in untrained older women, regardless of training volume. Furthermore, changes in MQ were positively correlated with changes in PhA (r = 0.60, P < 0.01).     

Measurement Errors in Modified Pull-Ups Testing

In a review of 46 meta-analyses of gender differences, overhand throwing had the largest gender difference favoring boys (ES > 3.0). Expectations for gender-specific performances may be less pronounced in female Australian Aborigines, because historical accounts state they threw for defense and hunting. Overhand throwing velocities and kinematics were recorded in 30 female and male Aboriginal Australian children 6-10 years old. Results indicated the Aboriginal girls and boys were more similar in horizontal ball velocities than U.S. girls and boys. Throwing kinematics between girls and boys were also more similar in Australian Aborigines than U.S. children. Aboriginal girls threw with greater velocities than U.S., German, Japanese, and Thai girls, while the boys were similar across cultures.     

Is passive drag dependent on the interaction of kayak design and paddler weight in flat-water kayaking?

Abstract

Drag is one of the major factors that influences kayaking performance. To focus on the drag of the kayak’s hull shape and the paddlers’ weight per se, the passive drag (D_p) was measured on a flat-water sprint course for one paddler with added weights. D_p was measured by an electromechanical towing device using a load cell, at incremental and constant velocities from 2.78 to 5.56 m/s. Three kayaks of different sizes and shapes (Nelo® K1 Quattro-M, ML, and L) were used and the paddlers’ body weight was adjusted with weights so the total paddler weight in the kayak was 65, 75, and 85 kg. The mean D_p increased by the power function of D = kvⁿ (mean R² = .990; SD .006). The D_p went from 21.37?±?1.29 N at 2.78 m/s to 89.32?±?6.43 N at 5.56 m/s. For the two lighter weighted kayaks (65 and 75 kg), the lowest D_p was observed with different kayak sizes (M, ML, or L) depending on the target velocity. The manufacturers suggest that paddlers should select a kayak size according to their body weight to minimise drag; however, the results of this study suggest that target velocities, and thus competition distance should also be factored into kayak selection.     

Training priority: Positive suggestions

“Keep the sand low, Mike, so it doesn't accidentally get in someone's eyes. That would hurt. Yes, like that — you and Jonathan are building some very long roads. Would a little water help you pack them smoothly?” This teacher's tone of voice is accepting, and her words show understanding of the lifelong learning process.     

Irish education and the legacy of O’Connell

In 1831, the British Government decided to become directly involved in the provision of elementary education in Ireland, a country over which it then had jurisdiction. By European standards of the time this was a highly unusual step. A number of scholars have interrogated the factors that led to this outcome as well as the role played by various individuals. Daniel O’Connell’s activities, at this time, have been described as relatively limited, which appears incongruous given that he is considered the most powerful Irish politician of this era and was then at the height of his powers. It is the central contention of this article that O’Connell was, in fact, intimately involved in bringing about a national system of elementary education. Of more lasting significance is the manner in which he defined the role of the politician vis-à-vis the Church authorities in educational policy-making. In this regard he established a pattern that remained unchanged for over a century and indeed, it could be argued, largely persists to this day.     

Validation and profile of Chinese pre-service teachers’ technological pedagogical content knowledge scale

Researchers state that teachers in different contexts reported different technological pedagogical content knowledge (TPACK). This phenomenon may partially be explained by cultural differences. Based on this consideration, the development and validation of the Chinese pre-service teachers’ technological pedagogical content knowledge (CTPCK) scale is described in this article. The sample was split into two subsamples on random basis (n1 = 229, n2 = 207) for the purpose of conducting (1) exploratory factor analysis (EFA) and (2) confirmatory factor analysis (CFA), respectively. After the EFA, the CTPCK scale excluded six items and included eight factors with 42 items. Reliability and correlations were discussed. The findings revealed that the CTPCK scale was a valid and reliable instrument for measuring the TPACK of Chinese pre-service teachers’ knowledge with or without linking educational technology.     

Essential Conditions for Technology-Supported,Student-Centered Learning: An Analysis of Student Experiences With Math Out Loud Using the ISTE Standards for Students

This article explores links between student experiences with technology-rich mathematics instruction and the ISTE Standards for Students. Research methods applied constructivist grounded theory to analyze data from student interviews against the ISTE Standards for Students to identify which elements of the design of this learning environment seemed to support the attainment of both mathematics content objectives and the ISTE Standards for Students. Researchers then identify guiding principles for the effective design of technology-supported, student-centered learning environments based on analysis of the results. (Keywords: ISTE standards, mathematics education, student- created work, technology-rich learning)     

Volume contents

Volume Contents

Volume contents