The relationship between strength asymmetries and jumping performance in professional volleyball players

Knee peak torque (PT) is associated to jump performance in volleyball players. It is not clear whether muscle strength imbalances of the knee joint can influence jump performance. The purpose of study was to analyse the association between PT and knee muscular imbalances with jump performance in professional volleyball players. Eleven elite male volleyball players (90.3 ± 9.7 kg body mass and 1.94 ± 0.06 m height) were evaluated in an isokinetic dynamometer at speeds of 60, 180 and 300 deg/s. Muscle strength imbalances were obtained through calculation of contralateral deficit between limbs and the conventional ratio (hamstrings/quadriceps). Countermovement jump (CMJ) was performed on a force plate to calculate mechanical power and height. Association was found between knee extensor PT at 180 deg/s with CMJ power (r = 0.610, p = 0.046). Conventional ratio at 300 deg/s showed negative association with CMJ (r = ?0.656, p = 0.029). The optimal ratio between knee extensors PT in relation to the flexors PT is associated with the greater mechanical power in CMJ. Contralateral deficit does not seem to be associated with the CMJ performance. Considering the knee extensor PT is associated with CMJ power, our findings suggest that strength-based training in volleyball athletes should not omit the conventional muscle ratio.     

Analyzing ICT adoption and use effects on knowledge creation: An empirical investigation in SMEs

This paper investigates the influence of the adoption and use of information and communication technology (ICT) on organizational learning (OL). The focus is on knowledge, creation, as an articulated construct for the OL concept, and the SECI (Socialization, Externalization, Combination and Internalization) model is used as a reference for knowledge, creation. ICT use is seen here as consisting of three different orientations: informative, communicative and workflow. The results, based on a sample of around 300 Spanish small- and, medium-sized enterprises (SMEs), indicate that ICT has a significant positive influence on the, four processes for creating knowledge. ICT oriented to communication and workflow is found, to produce a significant positive impact on knowledge creation processes, except for, socialization process, while ICT use for information does not influence any of the processes for, creating knowledge and OL.     

Reflection-on-action learning through traditional games. The case of la pelota sentada (sitting ball) / Aprendizaje basado en la reflexión sobre la acción a través de los juegos tradicionales. El caso de la pelota sentada

Traditional paradoxical games enable democratic social encounters as well as reflective skills to be fostered among students. The rules of these games, of which the game pelota sentada (sitting ball) is an example, afford players autonomy to decide either to cooperate with other participants (to release or keep others free) or to oppose them (to capture free players). The aim of this study was to investigate the reflection-on-action about decisions (strategies), relationships and emotions of the participants in the game sitting ball when in the role of free player in possession of the ball. Undergraduate degree students (n = 106) in physical activity and sport sciences took part. After the game, the players answered reflection-on-action open-ended and close-ended questions about their strategies, relationships and emotions. Four experts followed a validated directed and summative approach to the content analysis of 742 comments, using ATLAS.ti software. The findings highlight that decisions, relationships and emotions are distinct yet intertwined dimensions of the same phenomenon: motor conduct in the game pelota sentada (sitting ball).     

Activity of periscapular muscles and its correlation with external oblique during push-up: Does scapular dyskinesis change the electromyographic response?

Scapular dyskinesis is the term used to describe changes in the positioning or movement of the scapula. Such dysfunction is associated with changes in the activation of the scapular muscles. However, the influence of the axial muscles on the scapular muscles activity of subjects with scapular dyskinesis is unknown. This study aimed to compare the electromyography (EMG) activity of periscapular muscles and its correlation with the external oblique muscle during the execution of push-up performed in different surfaces, in volunteers with and without scapular dyskinesis. Thirty-six men, divided in two groups (control and dyskinesis), performed push-up on stable and unstable surface. The EMG activity of serratus anterior (SA_5th and SA_7th fibers), upper (UT) and lower (LT) trapezius, external oblique (EO) was recorded during execution of each task condition. Statistical analyzes were performed using two way ANOVA repeated measures and Pearson correlation. It was observed effect of interaction between factors, being evidenced increased activity of UT, SA_7th and OE for the control group and decreased activity of SA_5th, SA_7th and EO for dyskinesis group during execution of push-up on unstable surface. In both groups positive correlations (r > 0.47) were observed between EMG activity of SA and EO. In the exercises tested, there seems to be an anatomical and functional relationship between the SA and EO muscles. The use of the unstable surface promotes increased neuromuscular demand, but the neuromuscular strategies appear to differ between groups.     

Interferential therapy effect on mechanical pain threshold and isometric torque after delayed onset muscle soreness induction in human hamstrings

Abstract

This study was undertaken to examine the acute effect of interferential current on mechanical pain threshold and isometric peak torque after delayed onset muscle soreness induction in human hamstrings. Forty-one physically active healthy male volunteers aged 18?33 years were randomly assigned to one of two experimental groups: interferential current group (n = 21) or placebo group (n = 20). Both groups performed a bout of 100 isokinetic eccentric maximal voluntary contractions (10 sets of 10 repetitions) at an angular velocity of 1.05 rad · s^?1 (60° · s^?1) to induce muscle soreness. On the next day, volunteers received either an interferential current or a placebo application. Treatment was applied for 30 minutes (4 kHz frequency; 125 μs pulse duration; 80?150 Hz bursts). Mechanical pain threshold and isometric peak torque were measured at four different time intervals: prior to induction of muscle soreness, immediately following muscle soreness induction, on the next day after muscle soreness induction, and immediately after the interferential current and placebo application. Both groups showed a reduction in isometric torque (P < 0.001) and pain threshold (P < 0.001) after the eccentric exercise. After treatment, only the interferential current group showed a significant increase in pain threshold (P = 0.002) with no changes in isometric torque. The results indicate that interferential current was effective in increasing hamstrings mechanical pain threshold after eccentric exercise, with no effect on isometric peak torque after treatment.     

The impact of structured teaching methods on the quality of education in Brazil

This paper estimates the impact of the use of structured methods on the quality of education for students in primary public school in Brazil. Structured methods encompass a range of pedagogical and managerial instruments applied in the educational system. In recent years, several municipalities in the state of São Paulo have contracted out private educational providers to implement these structured methods in their schooling systems. Their pedagogical proposal involves structuring of curriculum content, development of teacher and student textbooks, and the training and supervision of teachers and instructors. Using a difference-in-differences estimation strategy, we find that the 4th- and 8th-grade students in the municipalities with structured methods performed better in Portuguese and mathematics than did students in municipalities not exposed to these methods. We find no differences in passing rates. A robustness test supports the assumption that there is no unobserved municipal characteristics associated with proficiency changes over time that may affect the results.     

“How do You Know this Answer?” – Children’s Use of Text Data and General Knowledge in Story Comprehension

This study investigates how, and to what extent, young readers (7–8 year-olds) use text information or their prior knowledge when answering comprehension questions about narrative texts. The children were asked to explain how they found out their responses by answering the following question: “how do you know this answer?” Their answers and justifications were analysed both qualitatively and quantitatively. The text proved to be the main source of information for these readers. However, sometimes the children seemed to ignore the text and over rely on their prior knowledge to answer the questions. The procedure of asking children to justify their answers was shown to be a good way of specifying more precisely some of their problems in text comprehension. It also seemed to encourage them to look back at the text and review their responses and, as such, it could be considered a useful tool to improve children’s reading comprehension.