The effect of biofeedback training on affective regulation and simulated car-racing performance: A multiple case study analysis     

William A. Edmonds  Gershon Tenenbaum  Derek T. Y. Mann  Michael Johnson  Akihito Kamata 《Journal of sports sciences》2013,31(7):761-773

Abstract

In this study, we wished to investigate the factors that determine the direction of the spin axis of a pitched baseball. Nineteen male baseball pitchers were recruited to pitch fastballs. The pitching motion was recorded with a three-dimensional motion analysis system (1000 Hz), and the orientations of the hand segment in a global coordinate system were calculated using Euler rotation angles. Reflective markers were attached to the ball, and the direction of the spin axis was calculated on the basis of their positional changes. The spin axis directions were significantly correlated with the orientations of the hand just before ball release. The ball is released from the fingertip and rotates on a plane that is formed by the palm and fingers; the spin axis of the ball is parallel to this plane. The lift force of the pitched baseball is largest when the angular and translational velocity vectors are mutually perpendicular. Furthermore, to increase the lift forces for the fastballs, the palm must face home plate.  相似文献   

The influence of pitch dimensions on performance during small-sided and conditioned soccer games     

Luís Vilar  Ricardo Duarte  Pedro Silva  Jia Yi Chow  Keith Davids 《Journal of sports sciences》2013,31(19):1751-1759

Abstract

This study examined the influence of pitch dimensions in small-sided soccer games in shaping opportunities for performers to maintain ball possession, pass to teammates and shoot at goal. Fifteen amateur standard male participants (M = 21.87, σ = 1.96 years) played 5 v 5 small-sided soccer games in three varying pitch conditions (28 m × 14 m, 40 m × 20 m and 52 m × 26 m). Thirty sequences of play in each condition were selected for digitisation using TACTO software, allowing the capture of bi-dimensional displacement coordinate data of all players and the ball. The values of interpersonal distance between all attackers and immediate defenders and the relative distances of defenders to intercept a shot and a pass were computed as dependent variables. Results showed existence of fewer opportunities to maintain ball possession on smaller pitches, compared to medium and larger pitches. Conversely, the different dimensions set to the pitch did not influence opportunities for players to shoot at goal, or to perform passes to other teammates. By examining the specific spatial–temporal relationships of players and key-task constraints, the data from this study explain how effects of manipulating pitch dimensions of small-sided games might enhance opportunities for acquiring specific movement and decision-making skills.  相似文献   

Creatine supplementation does not decrease oxidative stress and inflammation in skeletal muscle after eccentric exercise     

Luciano A. Silva  Camila B. Tromm  Guilherme Da Rosa  Karoliny Bom  Thais F. Luciano  Talita Tuon 《Journal of sports sciences》2013,31(11):1164-1176

Abstract

Thirty-six male rats were used; divided into 6 groups (n = 6): saline; creatine (Cr); eccentric exercise (EE) plus saline 24 h (saline + 24 h); eccentric exercise plus Cr 24 h (Cr + 24 h); eccentric exercise plus saline 48 h (saline + 48 h); and eccentric exercise plus Cr 48 h (Cr + 48h). Cr supplementation was administered as a solution of 300 mg · kg body weight^?1 · day^?1 in 1 mL water, for two weeks, before the eccentric exercise. The animals were submitted to one downhill run session at 1.0 km · h^?1 until exhaustion. Twenty-four and forty-eight hours after the exercise, the animals were killed, and the quadriceps were removed. Creatine kinase levels, superoxide production, thiobarbituric acid reactive substances (TBARS) level, carbonyl content, total thiol content, superoxide dismutase, catalase, glutathione peroxidase, interleukin-1b (IL-1β), nuclear factor kappa B (NF-kb), and tumour necrosis factor (TNF) were analysed. Cr supplementation neither decreases Cr kinase, superoxide production, lipoperoxidation, carbonylation, total thiol, IL-1β, NF-kb, or TNF nor alters the enzyme activity of superoxide dismutase, catalase, and glutathione peroxides in relation to the saline group, respectively (P < 0.05). There are positive correlations between Cr kinase and TBARS and TNF-α 48 hours after eccentric exercise. The present study suggests that Cr supplementation does not decrease oxidative stress and inflammation after eccentric contraction.  相似文献   

A Psychophysiological Assessment of Elite Wrestlers     

John M. Silva III  Barry B. Shultz  Robert W. Haslam  Donald Murray 《Research quarterly for exercise and sport》2013,84(3):348-358

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Technical Reliability Assessment of the Actigraph GT1M Accelerometer     

Pedro Silva  Jorge Mota  Dale Esliger  Gregory Welk 《Measurement in physical education and exercise science》2013,17(2):79-91

The purpose of this study was to determine the reliability of the Actigraph GT1M (Pensacola, FL, USA) accelerometer activity count and step functions. Fifty GT1M accelerometers were initialized to collect simultaneous acceleration counts and steps data using 15-sec epochs. All reliability testing was completed using a mechanical shaker plate to perform six different test conditions in Experiment 1 and 18 test conditions in Experiment 2. The overall intra- and inter-instrument reliability of the GT1M was CV_intra = 2.9% and CV_inter = 3.5% for counts and CV_intra = 1.1% and CV_inter = 1.2% for steps. No batch effects were evident in the 50 GT1Ms. The Actigraph GT1M accelerometer demonstrated good reliability for measuring both counts and steps. However, the ability of the GT1M to consistently detect acceleration at a given acceleration and frequency condition varied widely. Future studies clarifying the filtering limitations and the threshold necessary to detect the occurrence of movement are warranted.  相似文献   

Too little or too much? Parafoveal preview benefits and parafoveal load costs in dyslexic adults     

Susana Silva  Luís Faísca  Susana Araújo  Luis Casaca  Loide Carvalho  Karl Magnus Petersson  Alexandra Reis 《Annals of dyslexia》2016,66(2):187-201

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Faith,Race, and LGB Affirmation: Experiences of African American Counselors‐in‐Training          下载免费PDF全文

Janeé R. Avent Harris  Derek L. Roberston  Brenda Jones  Ashley M. Prado 《Counselor Education & Supervision》2017,56(2):145-158

In this phenomenological study, the authors investigated the experiences of African American counselors‐in‐training, with roots in the Black church, as they navigated their faith and professional responsibilities to provide affirming services to lesbian, gay, and bisexual clients. Findings suggest attitudes toward lesbian, gay, and bisexual clients are intertwined with faith, race, and community allegiance.  相似文献   

Stairway to employment? Internships in higher education     

Patrícia Silva  Betina Lopes  Marco Costa  Dina Seabra  Ana I. Melo  Elisabeth Brito  Gonçalo Paiva Dias 《Higher Education》2016,72(6):703-721

This article aims to shed light on the current debate regarding the role of internships in higher education in graduates’ employability. In specific, it analyses empirical data on a large-scale study of Portuguese first-cycle study programmes, in order to explore indicators of the professional value of internships in the employability of higher education graduates. Results demonstrate that study programmes that include internships tend to significantly enhance graduates’ employability, particularly within the universe of polytechnic and public higher education institutions. Besides the instrumental value of internships, the impact of the nature and structure of the internship on the percentage of unemployed graduates are also discussed. Mandatory internships and the inclusion of multiple, shorter internships throughout the degree are negatively associated with unemployment levels. Results indicate work-based learning can be used as a successful strategy to bridge theoretical knowledge and practice and enhance graduate employability. These findings provide important insights for the evaluation and/or the design of internship programmes in higher education.  相似文献   

A cross-national survey of cultural expectations and sex-role standards in reading     

John Downing  Carol A. Dwyer  Dina Feitelson  Mogens Jansen  Ritva Kemppainen  Hilkka-Liisa Matihaldi  David R. Reggi  Takahiko Sakamoto  Hugh Taylor  Derek V. Thackray  Douglas Thomson 《Journal of Research in Reading》1979,2(1):8-23

Cultural expectations and sex-role standards about reading in Canada, Denmark, England, Finland, Israel, Japan, and U.S.A. were investigated. A picture test showing various activities and objects including reading and books was administered in each country to six sub-samples that approximated to the levels: students in grades I, IV, VIII, and XII, college students, and adults. Subjects had to ascribe the activity or object as being appropriate for either a boy or a girl. The results were consistent with the hypothesis that cultural expectations and sex-role standards about reading are congruent within one country but that they differ between countries. In particular, boys in Canada and the U.S.A. rapidly learn to perceive reading as a feminine activity, whereas Danish and Japanese males at all ages consistently view reading as acceptable masculine behaviour.  相似文献   

Planning for Reform-Based Science: Case Studies of Two Urban Elementary Teachers     

Elaine Silva Mangiante 《Research in Science Education》2018,48(1):207-232

The intent of national efforts to frame science education standards is to promote students’ development of scientific practices and conceptual understanding for their future role as scientifically literate citizens (NRC 2012). A guiding principle of science education reform is that all students receive equitable opportunities to engage in rigorous science learning. Yet, implementation of science education reform depends on teachers’ instructional decisions. In urban schools serving students primarily from poor, diverse communities, teachers typically face obstacles in providing reform-based science due to limited resources and accountability pressures, as well as a culture of teacher-directed pedagogy, and deficit views of students. The purpose of this qualitative research was to study two white, fourth grade teachers from high-poverty urban schools, who were identified as transforming their science teaching and to investigate how their beliefs, knowledge bases, and resources shaped their planning for reform-based science. Using the Shavelson and Stern’s decision model for teacher planning to analyze evidence gathered from interviews, documents, planning meetings, and lesson observations, the findings indicated their planning for scientific practices was influenced by the type and extent of professional development each received, each teacher’s beliefs about their students and their background, and the mission and learning environment each teacher envisioned for the reform to serve their students. The results provided specific insights into factors that impacted their planning in high-poverty urban schools and indicated considerations for those in similar contexts to promote teachers’ planning for equitable science learning opportunities by all students.  相似文献