The effects of static stretching on speed and agility: One or multiple repetition protocols?     

Alexandra Avloniti  Ioannis G. Fatouros  Maria Protopapa  Ioannis Athanailidis  Christina Avloniti 《European Journal of Sport Science》2016,16(4):402-408

Although static stretching (SS) is utilized during warm-up before training and competition, the results about its effects on performance remain controversial. We examined whether performing a stretch of short-to-moderate duration (<60 sec) in a single repetition produces a similar or different effect on speed and agility performance from the effect which is produced while performing the same stretch in multiple repetitions of the same total duration. According to a repeated measurement design, 40 trained males were randomly assigned to either (1) a single repetition group or (2) a multiple repetition group. The participants in each group performed five trials: a control trial (no stretches were performed) and four experimental trials of SS protocols consisting of five exercises performed at either 20 sec (2 × 10 in the second group), 30 sec (3 × 10 in the second group), 40 sec (4 × 10 in the second group) or 60 sec (6 × 10 in the second group) of total duration. A two-way repeated measures analysis of variance showed that the participants in both group improved their speed performance in response to the 20-sec trial, whereas agility remained unaffected. Data analysis also revealed that the repetition number did not affect speed and agility performance. These data suggest that SS of short duration (<30 sec) may actually improve acute speed performance, whereas SS of moderate duration may not hamper speed and agility performance. Moreover, the effects of SS protocols are related to the total duration of each exercise and not to the number of repetitions in which each exercise is performed.  相似文献   

One hundred and fifty years of sprint and distance running – Past trends and future prospects     

Martin Weiss  Alexandra Newman  Ceri Whitmore  Stephan Weiss 《European Journal of Sport Science》2016,16(4):393-401

Sprint and distance running have experienced remarkable performance improvements over the past century. Attempts to forecast running performances share an almost similarly long history but have relied so far on relatively short data series. Here, we compile a comprehensive set of season-best performances for eight Olympically contested running events. With this data set, we conduct (1) an exponential time series analysis and (2) a power-law experience curve analysis to quantify the rate of past performance improvements and to forecast future performances until the year 2100. We find that the sprint and distance running performances of women and men improve exponentially with time and converge at yearly rates of 4% ± 3% and 2% ± 2%, respectively, towards their asymptotic limits. Running performances can also be modelled with the experience curve approach, yielding learning rates of 3% ± 1% and 6% ± 2% for the women's and men's events, respectively. Long-term trends suggest that: (1) women will continue to run 10–20% slower than men, (2) 9.50 s over 100 m dash may only be broken at the end of this century and (3) several middle- and long-distance records may be broken within the next two to three decades. The prospects of witnessing a sub-2 hour marathon before 2100 remain inconclusive. Our results should be interpreted cautiously as forecasting human behaviour is intrinsically uncertain. The future season-best sprint and distance running performances will continue to scatter around the trends identified here and may yield unexpected improvements of standing world records.  相似文献   

Theory of mind in dogs?: examining method and concept     

Horowitz A 《Learning & behavior》2011,39(4):314-317

In line with other research, Udell, Dorey, and Wynne’s (in press) finding that dogs and wolves pass on some trials of a putative theory-of-mind test and fail on others is as informative about the methods and concepts of the research as about the subjects. This commentary expands on these points. The intertrial differences in the target article demonstrate how critical the choice of cues is in experimental design; the intersubject-group differences demonstrate how life histories can interact with experimental design. Even the best-designed theory-of-mind tests have intractable logical problems. Finally, these and previous research results call for the introduction of an intermediate stage of ability, a rudimentary theory of mind, to describe subjects’ performance.  相似文献   

Toward an Integrated Framework of Multiple Text Use     

Alexandra List 《教育心理学家》2019,54(1):20-39

We introduce the Integrated Framework of Multiple Texts to understand how students use and form connections between multiple texts to accomplish personal or task goals. The Integrated Framework of Multiple Texts conceptualizes students’ multiple text use as unfolding over the course of three stages—preparation, execution, and production. In the preparation stage of the framework, individual difference factors and students’ task analysis result in learners’ adoption of a default stance, or a general orientation, toward multiple text use. During the execution stage of the framework, students engage in a variety of behavioral, cognitive, and metacognitive/regulatory strategies to develop cross-textual links and to integrate information across multiple texts. The execution stage concludes with students’ development of a variety of affective and cognitive outcomes as a consequence of text access. Finally, in the production stage of the framework, students draw on these affective and cognitive outcomes to develop external, often written products.  相似文献   

Field Trips in Early Childhood Settings: Expanding the Walls of the Classroom     

Satomi Izumi Taylor  Vivian Gunn Morris  Carol Cordeau-Young 《Early Childhood Education Journal》1997,25(2):141-146

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Black School,White School: Racism and Educational (Mis)Leadership. Jeffrey S. Brooks. New York,NY: Teachers College Press, 2012, 153 pp., $28.95     

Lucy E. Bailey  Alexandra J. Holter 《Educational Studies A Journal of the American Educational Studies Association》2016,52(4):381-384

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Digital Work Practices: Affordances in Design Education     

Alexandra Crosby  Kane Pham  J. Fiona Peterson  Thomas Lee 《The International Journal of Art & Design Education》2020,39(1):22-37

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Gender equality in the Olympic Movement: not a simple question,not a simple answer     

Alexandra Avena Koenigsberger 《体育哲学杂志》2017,44(3):329-341

This article explores the strategies followed by the International Olympic Committee for the achievement of gender equality. It is argued that this international body can go beyond simply adopting an equality of opportunities approach to gender equality. It suggests which other strategies can be incorporated for which it draws on the different ways of understanding gender equality in gender political theory.  相似文献   

Understanding key performance indicators for breast support: An analysis of breast support effects on biomechanical,physiological and subjective measures during running     

Debbie Risius  Alexandra Milligan  Jason Berns  Nicola Brown 《Journal of sports sciences》2017,35(9):842-851

To assess the effectiveness of breast support previous studies monitored breast kinematics and kinetics, subjective feedback, muscle activity (EMG), ground reaction forces (GRFs) and physiological measures in isolation. Comparing these variables within one study will establish the key performance variables that distinguish between breast supports during activities such as running. This study investigates the effects of changes in breast support on biomechanical, physiological and subjective measures during running. Ten females (34D) ran for 10 min in high and low breast supports, and for 2 min bare breasted (2.8 m·s^?1). Breast and body kinematics, EMG, expired air and heart rate were recorded. GRFs were recorded during 10 m overground runs (2.8 m·s^?1) and subjective feedback obtained after each condition. Of the 62 variables measured, 22 kinematic and subjective variables were influenced by changes in breast support. Willingness to exercise, time lag and superio-inferior breast velocity were most affected. GRFs, EMG and physiological variables were unaffected by breast support changes during running. Breast displacement reduction, although previously advocated, was not the most sensitive variable to breast support changes during running. Instead breast support products should be assessed using a battery of performance indicators, including the key kinematic and subjective variables identified here.  相似文献   

Exergames ‘as a teacher’ of movement education: exploring knowing in moving when playing dance games in physical education     

Gunn Nyberg  Jane Meckbach 《Physical Education & Sport Pedagogy》2017,22(1):1-14

Background: A fundamental dimension of school physical education (PE) is arguably movement and movement activities. However, there is a lack of discussion in the context of PE regarding what can be called the capability to move in terms of coordinative abilities, body consciousness and educing bodily senses.

Purpose: This article explores and articulates what there is to know, from the mover's perspective, when knowing how to move in specific ways when playing exergames (dance games). Taking different ways of moving as expressing different ways of knowing as a point of departure, the following questions are the focus of this article: (i) How do students move when imitating movements in a dance game, and what different ways of knowing the movements can be described in the student group? (ii) What aspects of the movements are discerned simultaneously through the different ways of knowing the movements? (iii) What aspects seem critical for the students to discern and experience in order to know the movements in as complex a way as possible?

Design and analysis: The theoretical point of departure concerns an epistemological perspective on the capability to move as knowing how with no distinction between physical and mental skills, and also knowing as experiencing aspects of something to know. The data in this study comprise video recordings of students playing Nintendo Wii dance games in PE lessons in a compulsory school (for children aged between 7 and 16 years) in a small Swedish town. There were three PE lessons with four different stations, of which one was Nintendo Wii dance games (Just Dance 1 and 2). In total, the videoed material covers three 60-minute PE lessons, recorded during the autumn of 2012 and in which just over twenty students participated. In the study, we have used video observation as a data collection method. Jordan and Henderson maintain that video observation removes the gap between ‘what people say they do and what they, in fact, do’ (51). To conduct a systematic and thorough analysis of how the students experienced the avatar's movements, we looked for moments where all the students and the avatar could be simultaneously observed. Two video sequences were chosen, showing four students imitating two distinct and defined movements which constituted the basis for a phenomenographic analysis.

Conclusion: The result of the phenomenographic analysis shows different ways of knowing the movements as well as what aspects are discerned and experienced simultaneously by the students. In other words, these aspects also describe knowing in terms of discerning, discriminating and differentiating aspects of ways of moving. By examining a certain exergame's role ‘as a teacher,' we have emphasized the capability to move, from the mover's perspective, as an intrinsic educational goal of PE while highlighting the need for systematically planning movement education.  相似文献