Influence of force-vector and force application plyometric training in young elite basketball players     

Oliver Gonzalo-Skok  Jorge Sánchez-Sabaté  Luis Izquierdo-Lupón  Eduardo Sáez de Villarreal 《European Journal of Sport Science》2019,19(3):305-314

Plyometric training composed by unilateral exercises with horizontal jumping direction seems to be an effective way to improve physical performance in athletes. The present study aimed to compare the influence of a combined jumping direction and force application (horizontal-unilateral vs. vertical-bilateral) plyometric training on linear sprinting, jumping, change of direction (COD) and dynamic balance in young elite basketball players. Twenty young (U-13 to U-14) male basketball players (age: 13.2?±?0.7 years, body mass: 59.5?±?12.7?kg, height: 172.9?±?7.9?cm) were randomly assigned either to a unilateral-horizontal (UH, n?=?10) or bilateral-vertical (BV, n?=?10) plyometric group, twice a week for 6-wk. Both groups performed between 60 and 100 jumps/session. UH executed all jumps unilaterally with horizontal direction, while jumps in the BV were bilaterally with vertical direction. Performance was assessed by a linear sprinting test, vertical and horizontal jumping tests, COD tests (V-cut and 5+5?m with a 180°COD test), an ankle dorsiflexion test and dynamic balance tests (anterior and postero-lateral directions). Within-group differences showed substantial improvements (Effect size (ES):0.31–1.01) in unilateral vertical and horizontal jumping, V-cut test and postero-lateral direction with right leg after both training interventions. Furthermore, UH group also substantially improved (ES:0.33–0.78) all sprinting times and postero-lateral direction with left leg, while BV enhanced anterior direction with left leg (ES:0.25). Between-group analyses showed substantially greater improvements (ES:0.33) in 10-m and V-cut test in UH than in BV. The likely beneficial effect (small ES) achieved in sprinting abilities suggests the combination of unilateral-horizontal jumps to improve such abilities.  相似文献   

Creating survival strategies: what can be learned from a science class?     

Maria Inês Mafra Goulart  Eduardo Sarquis Soares 《Cultural Studies of Science Education》2009,4(3):587-594

Elementary science teaching has been considered by recent researchers as a process in which students should be engaged in a variety of activities to develop science concepts, science process skills and scientific attitudes. From this perspective, hands-on activities are prominent in this approach because it leads the students to both reflect on the natural and physical world, and understand the social role of science in society. In Upadhyay’s article we follow an elementary teacher who struggles to implement a participatory method of science teaching in an environment that prioritizes high-stakes tests as the benchmarks for teachers’ and students’ success. In so doing, the teacher negotiates her identities in order to engage the students in the process of learning science even though the environment requires a teaching methodology that is against her beliefs. In our commentary on Upadhyay’s article we argue that (a) the tensions experienced by teachers create the core of the process of fluidity identity; (b) the different forms of external control over the teaching are inherent in educational systems and also a demand of parents and society; and (c) the possibility for social mobility of minority students is a complex process that goes beyond the dichotomy identified in Upadhyay’s article, namely that either the students learn to think scientifically, or the students learn tricks that enable them to succeed in the tests.

Eduardo Sarquis Soares (Corresponding author)Email:

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Costs and benefits of bilingual education in Guatemala: A partial analysis   总被引：1，自引：0，他引：1  

Harry Anthony Patrinos  Eduardo Velez   《International Journal of Educational Development》2009,29(6):594-598

The benefits of bilingual education for a disadvantaged indigenous population as an investment in human capital are significant. Students of bilingual schools in Guatemala have higher attendance and promotion rates, and lower repetition and dropout rates. Bilingual students receive higher scores on all subject matters, including mastery of Spanish. The efficiency of bilingual education is confirmed by a crude cost–benefit exercise. A shift to bilingual schooling would result in considerable cost savings because of reduced repetition. The higher quality of education generating higher promotion rates will help students complete primary education and will substantially increase completion rates at low cost. The costs saving due to bilingual education is estimated at $5 million, equal to the cost of primary education for 100,000 students.  相似文献   

Does Educational Preparation Match Professional Practice: The Case of Higher Education Policy Analysts     

Eduardo C. Arellano  Mario C. Martinez 《Innovative Higher Education》2009,34(2):105-116

This study compares the extent to which higher education policy analysts and master’s and doctoral faculty of higher education and public affairs programs match on a set of competencies thought to be important to higher education policy analysis. Analysts matched master’s faculty in three competencies while analysts and doctoral faculty matched in five competencies. The findings suggest possible reasons why analysts and graduate faculty agree or differ on various competencies. Also, the findings raise important questions regarding the preparation of higher education policy analysts and the graduate programs that educate them. This study is an addition to the body of competency literature. Eduardo C. Arellano  obtained a B.A. in Political Science and an M.P.A from the University of Texas at El Paso, and he holds the Ph.D. in Educational Administration from New Mexico State University. He is an assistant professor at New Mexico State University in the Department of Educational Management and Development. His special interests are interactional diversity, competency, and US–Mexico border studies. Mario C. Martinez  has a B.A. in Electrical Engineering from New Mexico State University, an M.B.A. from the University of Texas at Austin, and a Ph.D. in Educational Policy and Leadership from Arizona State University. He is an associate professor at the University of Nevada-Las Vegas in the department of Educational Leadership. His special interests are higher education policy, governance, finance, competency modeling, and strategy.  相似文献   

Effects of different intensities of resistance training with equated volume load on muscle strength and hypertrophy     

Thiago Lasevicius  Carlos Ugrinowitsch  Brad Jon Schoenfeld  Hamilton Roschel  Lucas Duarte Tavares  Eduardo Oliveira De Souza 《European Journal of Sport Science》2018,18(6):772-780

The present study investigated the effects of different intensities of resistance training (RT) on elbow flexion and leg press one-repetition maximum (1RM) and muscle cross-sectional area (CSA). Thirty men volunteered to participate in an RT programme, performed twice a week for 12 weeks. The study employed a within-subject design, in which one leg and arm trained at 20% 1RM (G20) and the contralateral limb was randomly assigned to one of the three conditions: 40% (G40); 60% (G60), and 80% 1RM (G80). The G20 started RT session with three sets to failure. After G20 training, the number of sets was adjusted for the other contralateral limb conditions with volume-matched. CSA and 1RM were assessed at pre, post-6 weeks, and post-12 weeks. There was time effect for CSA for the vastus lateralis (VL) (8.9%, 20.5%, 20.4%, and 19.5%) and elbow flexors (EF) (11.4%, 25.3%, 25.1%, and 25%) in G20, G40, G60, and G80, respectively (p?>?.05). G80 showed higher CSA than G20 for VL (19.5% vs. 8.9%) and EF (25% vs. 11.4%) at post-12 weeks (p?p?相似文献   

In-depth cross-coupling analysis in high-performance induction motor control     

Luis A. Amézquita-Brooks  Carlos E. Ugalde-Loo  Eduardo Licéaga-Castro  Jesús Licéaga-Castro 《Journal of The Franklin Institute》2018,355(5):2142-2178

High-performance field oriented control (FOC) of induction motors (IMs) relies on the accurate control of their electrical dynamics. In particular, perfect decoupling control of the stator currents should be ideally achieved for a FOC scheme to be efficient. However, the decoupling effectiveness afforded by most stator currents controllers may be influenced not only by the parameters and the operating condition, but also by the specific controller structure and the adopted coordinate system. A measure to assess decoupling effectiveness is non-existent in the IM control literature. To bridge this gap, an in-depth analysis of the cross-coupling inherent characteristics of the electrical subsystem of IMs under different well-known control structures is presented in this paper. Specifically, four control strategies previously studied and experimentally validated in the literature are critically assessed in this work: (1) stationary frame proportional-integral (PI) control, (2) synchronous frame PI control, (3) synchronous frame PI control with decoupling networks, and (4) improved stationary frame diagonal control. The decoupling capabilities of controllers in stationary and synchronous coordinates are examined, with a detailed insight on the role of decoupling methods. The analysis is performed in the frequency domain under the framework of individual channel analysis and design (ICAD). By application of ICAD, the decoupling effectiveness of FOC schemes is clearly exposed and quantified, with an assessment of the effects of parametric uncertainty being carried out for completeness. The effect of the inverter dynamics over cross-coupling is also treated using digital simulations. The results are useful to determine the conditions in which each control strategy has either advantages or disadvantages. Additionally, it is possible to determine the effect of several operating parameters over the stator currents cross-coupling such as nominal flux and torque levels.  相似文献   

Protection against muscle damage in competitive sports players: the effect of the immunomodulator AM3     

Córdova A  Martin JF  Reyes E  Alvarez-Mon M 《Journal of sports sciences》2004,22(9):827-833

Strenuous physical exercise of the limb muscles commonly results in damage, especially when that exercise is intense, prolonged and includes eccentric contractions. Many factors contribute to exercise-induced muscle injury and the mechanism is likely to differ with the type of exercise. Competitive sports players are highly susceptible to this type of injury. AM3 is an orally administered immunomodulator that reduces the synthesis of proinflammatory cytokines and normalizes defective cellular immune fractions. The ability of AM3 to prevent chronic muscle injury following strenuous exercise characterized by eccentric muscle contraction was evaluated in a double-blind and randomized pilot study. Fourteen professional male volleyball players from the First Division of the Spanish Volleyball League volunteered to take part. The participants were randomized to receive either placebo (n=7) or AM3 (n=7). The physical characteristics (mean+/-s) of the placebo group were as follows: age 25.7+/-2.1 years, body mass 87.2+/-4.1 kg, height 1.89+/-0.07 m, maximal oxygen uptake 65.3+/-4.2 ml.kg(-1).min(-1). Those of the AM3 group were as follows: age 26.1+/-1.9 years, body mass 85.8+/-6.1 kg, height 1.91+/-0.07 m, maximal oxygen uptake 64.6+/-4.5 ml.kg(-1).min(-1). All participants were evaluated for biochemical indices of muscle damage, including concentrations of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, creatine kinase (CK) and its MB fraction (CK-MB), myoglobin, lactate dehydrogenase, urea, creatinine and gamma-glutamyltranspeptidase, both before and 30 days after treatment (over the peak of the competitive season). In the placebo group, competitive exercise (i.e. volleyball) was accompanied by significant increases in creatine kinase (494+/-51 to 560+/-53 IU.l(-1), P < 0.05) and myoglobin (76.8+/-2.9 to 83.9+/-3.1 microg.l(-1), P < 0.05); aspartate aminotransferase (30.8+/-3.0 to 31.1+/-2.9 IU.l(-1)) and lactate dehydrogenase (380+/-31 to 376+/-29 IU.l(-1)) were relatively unchanged after the 30 days maximum effort. AM3 not only inhibited these changes, it led to a decrease from baseline serum concentrations of creatine kinase (503+/-49 to 316+/-37 IU.l(-1), P < 0.05) and myoglobin (80.1+/-3.2 to 44.1+/-2.6 IU.l(-1), P < 0.05), as well as aspartate aminotransferase (31.1+/-3.3 to 26.1+/-2.7 IU.l(-1), P < 0.05) and lactate dehydrogenase (368+/-34 to 310+/-3 IU.l(-1), P < 0.05). The concentration of CK-MB was also significantly decreased from baseline with AM3 treatment (11.6+/-1.2 to 5.0+/-0.7 IU.l(-1), P < 0.05), but not with placebo (11.4+/-1.1 to 10.8+/-1.4 IU.l(-1)). In conclusion, the use of immunomodulators, such as AM3, by elite sportspersons during competition significantly reduces serum concentrations of proteins associated with muscle damage.  相似文献   

The perception of workload and task complexity and its influence on students’ approaches to learning: a study in higher education     

Eva Kyndt  Filip Dochy  Katrien Struyven  Eduardo Cascallar 《European Journal of Psychology of Education - EJPE》2011,26(3):393-415

Researchers have tried to induce a deeper approach to learning by means of student-centred learning environments. Findings did not always confirm the positive hypotheses. This has given rise to the question as to what the discouraging or encouraging factors are for inducing a deep approach to learning. The aim of this research study is to determine whether perceived workload and task complexity are discouraging or encouraging factors. In addition, these relationships will be investigated under different induced conditions which offer the potential to deepen our understanding of the nature of the investigated relationships. Participants were 128 second year Bachelor level students in educational sciences. After an introduction with the theory, students were given four tasks with various workloads and task complexities after which they filled out questionnaires on learning approaches, perceived workload and perceived task complexity. For every task, correlations and multiple stepwise regressions were calculated. The information from the interviews was used to support and illustrate the results of quantitative analyses. In general, results show no significant relationship between perceived workload and students’ approaches to learning. For perceived task complexity, it was found that a perceived lack of information is a discouraging factor for inducing a deep learning approach. A lack of information consistently increases students’ surface approaches to learning regardless of the induced workload and task complexity.  相似文献   

NASA-TLX for predictability and measurability of instructional design models: case study in design methods     

Nikulin  Christopher  Lopez  Gabriela  Piñonez  Eduardo  Gonzalez  Luis  Zapata  Pia 《Educational technology research and development : ETR & D》2019,67(2):467-493

Educational technology research and development - Innovation projects has established as an emerging field of research, a number of issues have emerged; among the others, measurability and...  相似文献   

A shorter set reduces the loss of cardiac autonomic and baroreflex control after resistance exercise     

Xián Mayo  Eduardo Carballeira-Fernández  Miguel Fernández-Del-Olmo 《European Journal of Sport Science》2016,16(8):996-1004

Set configuration may affect the recovery pattern of cardiac vagal autonomic and reflex modulation after a resistance exercise, since it is closely associated with intensity and volume and determines the metabolic involvement of the session. We tested the hypothesis that longer set configurations have a higher impact on cardiac autonomic control and baroreflex sensitivity compared with shorter set configurations. We studied the effects of three set configurations with the same components of work on the cardiac autonomic control and baroreflex sensitivity. Seventeen subjects performed one control session and three experimental sessions of a leg-press exercise with the same volume (40 repetitions), resting time (720?s) and intensity (10RM load): (a) 5 sets of 8 repetitions with 3?min of rest between sets (8S), (b) 10 sets of 4 repetitions with 80?s of rest between sets (4S) and (c) 40 sets of 1 repetition with 18.5?s of rest between each repetition (1S). Longer set configurations (8S and 4S) induced greater reductions of the vagal cardiac autonomic control and baroreflex sensitivity (p?≤?.001) compared with a shorter set configuration (1S). Also, 1S had non-significant reductions versus the control session (p?>?.05). These findings suggest that a shorter set configuration can reduce the impact of resistance exercise on the post-exercise cardiac vagal autonomic control and baroreflex sensitivity.  相似文献