Decrements in knee extensor and flexor strength are associated with performance fatigue during simulated basketball game-play in adolescent,male players     

Aaron T Scanlan  Jordan L Fox  Nattai R Borges  Anne Delextrat  Tania Spiteri  Vincent J Dalbo 《Journal of sports sciences》2018,36(8):852-860

This study quantified lower-limb strength decrements and assessed the relationships between strength decrements and performance fatigue during simulated basketball. Ten adolescent, male basketball players completed a circuit-based, basketball simulation. Sprint and jump performance were assessed during each circuit, with knee flexion and extension peak concentric torques measured at baseline, half-time, and full-time. Decrement scores were calculated for all measures. Mean knee flexor strength decrement was significantly (P < 0.05) related to sprint fatigue in the first half (R = 0.65), with dominant knee flexor strength (R = 0.67) and dominant flexor:extensor strength ratio (R = 0.77) decrement significantly (P < 0.05) associated with sprint decrement across the entire game. Mean knee extensor strength (R = 0.71), dominant knee flexor strength (R = 0.80), non-dominant knee flexor strength (R = 0.75), mean knee flexor strength (R = 0.81), non-dominant flexor:extensor strength ratio (R = 0.71), and mean flexor:extensor strength ratio (R = 0.70) decrement measures significantly (P < 0.05) influenced jump fatigue during the entire game. Lower-limb strength decrements may exert an important influence on performance fatigue during basketball activity in adolescent, male players. Consequently, training plans should aim to mitigate lower-limb fatigue to optimise sprint and jump performance during game-play.  相似文献   

Body composition and hydration status changes in male and female open-water swimmers during an ultra-endurance event     

Roel Vaeyens  Aaron Coutts  Renaat M Philippaerts 《Journal of sports sciences》2013,31(10):1003-1012

Young adult soccer players often encounter difficulty progressing from youth competition to being regularly selected for high-level, open-age competition. In an attempt to increase the playing opportunities of semi-professional and amateur under-21 players in first teams, the Royal Belgian Football Association required national division teams to include at least two players younger than 21 in their match selection (under-21 rule). Over four seasons, the following variables were analysed across 2138 semi-professional and amateur soccer players aged 16?–?39 years: (1) the number of times a player was selected to be in the first team squad; (2) the number of times a player was selected to play in the starting line-up; and (3) the number of minutes played. Chi-square analysis demonstrated that second and third division teams had complied with the new selection regulations. However, two-way analysis of variance of individual player data revealed no increase in the number of playing minutes in the under-21 group. It would appear that many teams had complied with the new regulations by selecting young players as substitutes. The results highlight the difficulties that talented young soccer players experience progressing from youth to senior competition. We conclude that the rule imposed by the Royal Belgian Football Association has failed to improve the playing opportunities of young adult soccer players. Alternative strategies for increasing playing opportunities for young talented players are required.  相似文献   

Interactions among Dietary Pattern,Physical Activity and Skinfold Thickness     

Steven N. Blair  Aaron Blair  Russell R. Pate  Henry G. Howe  Morton Rosenberg  Gwynne M. Parker 《Research quarterly for exercise and sport》2013,84(4):505-511

Abstract

This study was designed to assess the effects of a specifically designed perceptual-motor training program on the level of perceptual-motor development, self-concept, and academic ability of kindergarten children. Subjects for the study were 40 kindergarten children randomly assigned to 1 of 2 groups. Each group received the same kindergarten program with one exception, the experimental group was exposed to a specifically designed perceptual-motor program 30 min daily for 5 mo, while the control group received a free play period for 30 min daily. Results of the study indicated that the data tended to support the specificity of training concept. The variables showing the greatest change were the perceptual-motor tests which measured changes on specific aspects of the training program. There appeared to be some immediate transfer to academic abilities but this was not pronounced enough to suggest that perceptual-motor training was of real benefit in developing academic abilities for normal kindergarten children. In addition the follow-up test indicated no long term effects on academic performance.  相似文献   

Reliability and validity of the Yo-Yo intermittent recovery test level 1 in young soccer players     

Dieter Deprez  Aaron James Coutts  Matthieu Lenoir  Job Fransen  Johan Pion  Renaat Philippaerts 《Journal of sports sciences》2013,31(10):903-910

Abstract

The present study investigated the test-retest reliability from the Yo-Yo IR1 (distance and heart rate responses), and the ability of the Yo-Yo IR1 to differentiate between elite and non-elite youth soccer players. A total of 228 youth soccer players (11–17 years) participated: 78 non-elite players to examine the test-retest reliability within 1 week, added with 150 elite players to investigate the construct validity. The main finding was that the distance covered was adequately reproducible in the youngest age groups (U13 and U15) and highly reproducible in the oldest age group (U17). Also, the physiological responses were highly reproducible in all age groups. Moreover, the Yo-Yo IR1 test had a high-discriminative ability to distinguish between elite and non-elite young soccer players. Furthermore, age-related standards for the Yo-Yo IR1 established for elite and non-elite groups in this study may be used for comparison of other young soccer players.  相似文献   

Weaving a New 'Net: A Mesh-Based Solution for Democratizing Networked Communications     

Aram Sinnreich  Nathan Graham  Aaron Trammell 《The Information Society》2013,29(5):336-345

Although the Internet is largely decentralized in its communication and social patterns, its technical and regulatory apparatuses are highly centralized and hierarchical. Consequently, digital communications are vulnerable to a degree of surveillance and censorship that would be unthinkable in traditional social arenas, threatening “Internet freedom” and cyberliberties in both democratic and politically repressed societies. We believe a new architecture is required in order to protect the continuance of civil liberties in networked society. In this article, we propose 10 “social specifications” describing the requirements of such a network, and outline an architecture called MondoNet that meets these specifications using ad hoc, wireless mesh networking technologies. We also address the legal and technical challenges facing the MondoNet project, and anticipate future developments in this field.  相似文献   

The origins of Penrose diagrams in Physics,Art, and the Psychology of perception, 1958–62     

Aaron Sidney Wright 《Endeavour》2013

  相似文献   

A toy model that predicts the qualitative role of bar bend in a push jerk     

Aaron Santos  Norman E. Meltzer 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(4):345-359

In this work, we describe a simple coarse-grained model of a barbell that can be used to determine the qualitative role of bar bend during a jerk. In simulations of this model, we observed a narrow time window during which the lifter can leverage the elasticity of the bar in order to lift the weight to a maximal height. This time window shifted to later times as the weight was increased. In addition, we found that the optimal time to initiate the drive was strongly correlated with the time at which the bar had reached a maximum upward velocity after recoiling. By isolating the effect of the bar, we obtained a generalized strategy for lifting heavy weight in the jerk.  相似文献   

Effects of psycholinguistic instruction on spelling performance     

Christopher T. Arra  P.G. Aaron 《Psychology in the schools》2001,38(4):357-363

Two studies were conducted in which phonology‐based instructional strategies designed for improving spelling skills of elementary school children were compared against instruction strategies that relied only on visual exposure of words. The first study involved a total of 93 children. Of these, 46 were instructed by drawing their attention to the psycholinguistic nature of their spelling errors. The remaining 47 children in the comparison group were shown the correct version of all the words. In study II 15 children were placed in a treatment group and were taught phoneme awareness, and 15 children were placed in a comparison group and were exposed to printed words only. In both studies, posttests showed that children taught through psycholinguistic and phoneme awareness methods significantly outperformed the visual training groups. Further, these gains were retained after a period of 2 weeks. © 2001 John Wiley & Sons, Inc.  相似文献   

Developmental dyslexia: Is it different from other forms of reading disability?     

P. G. Aaron 《Annals of dyslexia》1987,37(1):109-125

A controversy whether developmental dyslexia is qualitatively different from other forms of reading disability has existed among reading specialists for many years. In the present study, the hypothesis that the etiology of dyslexia is different from that of other forms of reading disability because of differences in the components that malfunction was tested. A number of studies have shown that the two components that contribute to a large proportion of variance in reading are decoding and comprehension. It is, therefore, possible that a breakdown of different components could lead to different forms of disabilities. College students who were poor readers were assigned to two groups on the basis of their IQ. Conforming to the traditional criterion of dyslexia, those who had an IQ of 95 and above were considered as dyslexic. Those who had an IQ of 85 or below were placed in the Nonspecific Reading-Disabled group. These two groups of poor readers and a group of normal readers were administered a large number of reading-related tests. It was found that the two reading-disabled groups differed from each other in six of the seven areas assessed. There was very little overlap of scores between the two groups in these areas. The results were interpreted to suggest that poor decoding skill is the etiology of developmental dyslexia and that it differs from other forms of reading disability which are caused by generalized cognitive deficits.  相似文献   

Field-based professional development of teachers engaged in distance education: experiences from the Arctic     

George Veletsianos  Aaron Doering  Jeni Henrickson 《Distance Education》2012,33(1):45-59

We examine the experiences of five teachers who traveled with a team of educators, scientists, and explorers on circumpolar Arctic expeditions to deliver adventure learning (AL) programs to K–12 students at a distance. Results highlight the personal and professional impacts this opportunity had on teachers, including their empowering, fulfilling, and mentally exhausting experiences while assisting in delivering distance education to students worldwide. The article concludes with a discussion of issues to consider in the development of similar programs.  相似文献