Physiological responses according to rules changes during 3 vs. 3 small-sided games in youth soccer players: stop-ball vs. small-goals rules     

Jamel Halouani  Alexandre Dellal  Anis Chaouachi  Karim Chamari 《Journal of sports sciences》2013,31(15):1485-1490

Abstract

Small-sided games (SSGs) are effective for soccer-specific aerobic endurance training. To date, no study has investigated the effect of stop-ball (SB-SSG) rule on the physiological responses to SSG. Therefore, the purpose of the present study was to examine the effects of SB-SSG vs. small-goals (SG-SSG) rules on physiological responses during a 3 vs. 3 SSG in young soccer players. Twelve male amateur young soccer players (age, 14.0 ± 0.7 years; body mass, 51.8 ± 8.0 kg; height, 164 ± 7 cm) randomly performed either SB-SSG or SG-SSG for 4 × 4 min separated by 2 min of recovery on a 20 × 15 m pitch. During the SB-SSG, participants were instructed to stop the ball with the soles of their boots in a 15 × 1 m surface behind the pitch bottom line; whereas during the SG-SSG, the participants were instructed to score to a mini-goal (i.e., 1 × 0.5 m). During each test session, the mean heart rate (HR), the post-SSG rating of perceived exertion (RPE) scores and blood lactate concentrations ([La^?]) were recorded. Results showed that SB-SSG induced significantly higher mean HR (178 ± 3 vs. 174 ± 3 bpm; P < 0.05) and [La^?] (4.66 ± 0.98 vs. 4.16 ± 1.02 mol · L^–1; P < 0.05) than SG-SSG. However, there was no significant difference between SB-SSG and SG-SSG for the RPE scores. In conclusion, the present study demonstrates the effectiveness of SB-SSG in SSG training. Indeed, SB-SSG can influence the effort intensity in SSG (i.e., resulted in a higher intensity than SG-SSG). Therefore, coaches have the possibility to choose between SB-SSG and SG-SSG rules during training sessions according to their physical and technical objectives.  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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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   

At the intersection between the subject and the political: a contribution to an ongoing discussion     

Alexandre Pais 《Educational Studies in Mathematics》2016,92(3):347-359

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成吉思汗在西南的后裔     

东人达 《内蒙古大学学报(人文社会科学版)》2004,36(1):21-25

在我国西南的云南、贵州、四川、重庆，生活着近7万名蒙古族民众，其中成吉思汗所属的奇渥温部后裔约占半数以上。几百年来，在对西南环境的适应过程中，他们形成了以山区农业为主的经济生活，原来的游牧化也随之发生了变化。但是，他们通过家谱、墓碑、口授的方式，传承着家族的历史和自己作为蒙古人的执信念。西南蒙古族具有明显的民族特征，其中内涵着宝贵的民族人资源。  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   

Time Constraints in the School Environment: What Does a Sleepy Student Tell Us?     

Luiz Menna-Barreto  Daniela Wey 《Mind, Brain, and Education》2008,2(1):24-28

ABSTRACT— In this article, we discuss school schedules and their implications in the context of chronobiological contemporary knowledge, arguing for the need to reconsider time planning in the school setting. We present anecdotal observations regarding chronobiological challenges imposed by the school system throughout different ages and discuss the effects of these schedules in terms of sleepiness and its deleterious consequences on learning, memory, and attention. Different settings (including urban vs. rural habitats) influence timing, which also depends on self-selected sleep schedules. Finally, we criticize the traditional view of a necessary strict stability of sleep–wake habits.  相似文献