Power training in elite young soccer players: Effects of using loads above or below the optimum power zone     

Irineu Loturco  Lucas A. Pereira  Valter P. Reis  Chris Bishop  Vinicius Zanetti  Pedro E. Alcaraz 《Journal of sports sciences》2020,38(11-12):1416-1422

ABSTRACT

This study aimed to examine the effects of two jump squat (JS) training programs involving different loading ranges in under-20 soccer players during a preseason period. Twenty-three elite young soccer players performed sprint speed (at 5-, 10-, and 20-m), change-of-direction (COD) speed, JS peak-power (PP), and countermovement jump (CMJ) tests pre and post four weeks of training. Athletes were pair-matched in two groups according to their optimum power loads (OPL) as follows: lower than OPL (LOPL; athletes who trained at a load 20% lower than the OPL) and higher than OPL (HOPL; athletes who trained at a load 20% higher than the OPL). Magnitude-based inferences were used to compare pre- and post-training measures. Meaningful increases in the PP JS were observed for both groups. Likely and possible improvements were observed in the 5- and 10-m sprint velocity in the LOPL group. Meanwhile, possible and likely improvements were observed in the CMJ, 5- and 10-m sprint velocity, and COD speed in the HOPL group. Overall, both training schemes induced positive changes in athletic performance. Soccer coaches and sport scientists can implement the JS OPL-based training schemes presented here, either separately or combined, to improve the physical performance of youth soccer players.  相似文献   

Correlation analysis of performance measures for multi-label classification     

Rafael B. Pereira  Alexandre Plastino  Bianca Zadrozny  Luiz H.C. Merschmann 《Information processing & management》2018,54(3):359-369

In many important application domains, such as text categorization, scene classification, biomolecular analysis and medical diagnosis, examples are naturally associated with more than one class label, giving rise to multi-label classification problems. This fact has led, in recent years, to a substantial amount of research in multi-label classification. In order to evaluate and compare multi-label classifiers, researchers have adapted evaluation measures from the single-label paradigm, like Precision and Recall; and also have developed many different measures specifically for the multi-label paradigm, like Hamming Loss and Subset Accuracy. However, these evaluation measures have been used arbitrarily in multi-label classification experiments, without an objective analysis of correlation or bias. This can lead to misleading conclusions, as the experimental results may appear to favor a specific behavior depending on the subset of measures chosen. Also, as different papers in the area currently employ distinct subsets of measures, it is difficult to compare results across papers. In this work, we provide a thorough analysis of multi-label evaluation measures, and we give concrete suggestions for researchers to make an informed decision when choosing evaluation measures for multi-label classification.  相似文献   

Initial Validity and Reliability of the Portuguese Borg Rating of Perceived Exertion 6-20 Scale     

Luana L. Cabral  Fábio Y. Nakamura  Joice M. F. Stefanello  Luiz C. V. Pessoa  Bruno P. C. Smirmaul  Gleber Pereira 《Measurement in physical education and exercise science》2020,24(2):103-114

ABSTRACT

The aims of this study were to perform the cross-cultural adaptation of the Borg Rating of Perceived Exertion (RPE) 6–20 Scale to Brazilian Portuguese language and to start testing its validity and reliability. After performing the cross-cultural adaptation of the Scale, concurrent and discriminative validity, and reliability were determined on a treadmill in young (18–30 years) and older adult women (60–75 years). Considering young and older adult women, RPE presented high and moderate positive correlation with heart rate and high and low positive correlation with oxygen consumption, respectively. Older adult women presented RPE (11 ± 2) significantly higher than young ones (8 ± 1) exercising at the same absolute intensity. Intraclass coefficient correlation was excellent for RPE to young and older adult women. The Scale presented concurrent validity only to young adult women, whereas it presented discriminative validity between such groups of women. Moreover, the scale is reliable to young and older adult women.  相似文献   

Non‐at‐risk adolescents' attitudes towards reading in a Singapore secondary school     

Wendy Bokhorst‐Heng  Delfin Pereira 《Journal of Research in Reading》2008,31(3):285-301

In this paper, we examine the various nuanced dimensions of adolescents' dispositions towards reading in one secondary school in Singapore, where a high‐stakes examination culture often threatens to colonise the practices of leisure reading. Our focus is on the better and more avid readers as they were the ones that developed the more negative attitudes towards reading at the end of their first year in secondary school. Our analysis found that there were no significant differences between boys and girls in their declining attitudes, and that for both ‘intrinsic motivation’ saw the greatest decline. However, attitudes related to learning orientation remained stable, suggesting both the impact of constraints in an exam‐oriented educational structure as well as possibilities for developing reading pedagogy and adolescent reading programmes. We argue that the more educators are aware of the multidimensionality and complexity of the attitudes and values that students bring to their reading, the more effectively they will be able to design and implement programmes and pedagogy to foster positive attitudes and promote a lifelong love for reading.  相似文献   

(Re) thinking Emotions in Visual Education Activities: Students' Experiences          下载免费PDF全文

Silvia Casian  Amélia Lopes  Fátima Pereira 《The International Journal of Art & Design Education》2018,37(3):399-412

This article focuses on the emotions of 13 and 14 year‐old students related to visual art education activities. Our aim is to understand the interference of the students' emotions with the processes of the creation and reception of their own pictures, as well as their characteristics in an art education context. The article adopts a Vygotskian theoretical perspective about emotion and aesthetic education that refers to the biopsychological nature of emotion and its cultural determination. The need to transform emotions in art activities is stressed and the teenagers' pictures are interpreted as a means of communication. The data collection was based on questionnaires and interviews with seventh and eighth grade secondary school students. It is concluded that students' emotions are not only present in the creative process and in its result, but also that they could have a significant positive or negative impact on students' motivation and achievement behaviour in art education classes. In this context, the students' pictures, acting as stimuli, may evoke their emotions.  相似文献   

Change-of direction deficit in elite young soccer players     

Irineu Loturco  Sophia Nimphius  Ronaldo Kobal  Altamiro Bottino  Vinicius Zanetti  Lucas A. Pereira  Ian Jeffreys 《Sportwissenschaft》2018,48(2):228-234

Change-of-direction (COD) ability is an essential physical component for soccer. This study examined the relationships between conventional speed–power assessments and COD performance in elite young soccer players. Twenty-five under-20 male players from the same club (age: 17.6?±?0.8 years, height: 178.1?±?6.7?cm, body mass [BM]: 72.2?±?7.9?kg) performed sprint speed tests, vertical jumps, loaded jump squats, half squats, and Zigzag COD assessments. Moreover, the COD deficit was calculated as the difference between 20-m sprint velocity and Zigzag COD test velocity. A Pearson correlation analysis was used to determine the correlations between Zigzag COD performance and COD deficit with speed and power outputs. Although no significant relationships between speed–power variables and COD ability were present, there were still strong positive correlations between traditional neuromechanical measures and COD deficit. Briefly, it seems that higher performances in speed and power tests are not necessarily related to better performances in specific COD maneuvers. Therefore, it is recommended that coaches and technical staff include specific COD drills in soccer player routines to optimize the transference from speed and power capacities to specific COD performance.  相似文献   

Ethics of social networks for special needs users     

Caroline Rizza  Ângela Guimarães Pereira 《Ethics and Information Technology》2013,15(4):249-251

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Effects of cigarette smoking on cardiac autonomic function during dynamic exercise     

Goncalo V. Mendonca  Fernando D. Pereira  Bo Fernhall 《Journal of sports sciences》2013,31(9):879-886

Abstract

The purpose of this study was to investigate the acute effect of cigarette smoking on cardiac autonomic function in young adult smokers during dynamic exercise. Fourteen healthy young smokers (21.4 ± 3.4 years) performed peak and submaximal exercise protocols under control and smoking conditions. Resting and submaximal beat-to-beat R-R series were recorded and spectrally decomposed using the fast Fourier transformation. Smoking resulted in a significant decrease in work time, [Vdot]O_2peak and peak O₂ pulse (P < 0.05). Heart rate increased at rest and during submaximal exercise after smoking (P < 0.05). The raw high frequency and low frequency power were significantly reduced by smoking, both at rest and during exercise (P < 0.05). The low to high frequency ratio was higher after smoking (P < 0.05). The normalised low frequency power was also significantly increased by smoking, but only at rest (P < 0.05). These data demonstrate that the tachycardic effect elicited by smoking is accompanied by acute changes in heart rate spectral components both at rest and during exercise. Therefore, the cardiac autonomic control is altered by smoking not only at rest, but also during exercise, resulting in reduced vagal modulation and increased sympathetic dominance.  相似文献   

Everyday life and everyday learning: the ways in which pre-service teacher education curriculum can encourage personal dimensions of teacher identity     

Amélia Lopes  Fátima Pereira 《欧洲师范教育杂志》2012,35(1):17-38

This article presents and discusses the findings of a research project, the main objective of which is to identify curriculum components that promote personal development as a nuclear part of teacher professional identity formation through pre-service teacher education. Curriculum is viewed as an ecological scenario with different subsystems and both as formal and informal. Identity formation is conceived as an ever-provisional result of a double transaction: the biographical one and the relational one. The curricula of four different historical periods of pre-service teacher education in Portugal and the professional identity of teachers trained within them were characterised through collection and analysis of documents and biographical narratives. Crossing results from the four periods, the quality of school climate emerges as an important variable to the quality of the teachers’ identity. The lifelong learning ethos seems to emerge when the training curriculum connects everyday learning with everyday life, namely by urging the students’ involvement in school life, peer learning activities and peer and teacher educators’ informal learning activities.  相似文献   

Adquisición de morfemas del español     

Miguel Pérez Pereira  Dolores Singer 《Infancia y Aprendizaje》2013,36(27-28):205-221

Resumen

Se han aplicado dos pruebas de palabras reales y palabras artificiales (semejante a la de Berko, 1958) a 109 niños hispano-parlantes de tres a seis años de edad, a fin de establecer la evolución en el uso de morfemas de plural, aumentativos y diminutivos, gerundio, pretérito imperfecto de indicativo y pretérito indefinido. Los resultados indican un progreso importante entre los tres y los cuatro años, siendo la curva posterior del desarrollo más suave. Se establece un orden de dificultad de estos morfemas, y se realiza un análisis de los errores cometidos, encontrándose también sobrerregularizaciones con verbos reales irregulares. Se extraen implicaciones acerca del proceso de adquisición de morfemas.  相似文献