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.     

A Cross-Linguistic,Longitudinal Study of the Foundations of Decoding and Reading Comprehension Ability

ABSTRACT

The present study investigated the moderating role of orthographic consistency on the development of reading comprehension in four language groups (English, n = 179; Spanish, n = 188; Czech, n = 135; Slovak, n = 194) from kindergarten to Grade 2. In all languages, early variations in phoneme awareness/letter knowledge, rapid automatised naming, and emerging decoding skills, but not oral language, predicted variations in decoding skills at the end of Grade 1; these in turn predicted reading comprehension in Grade 2. For the three consistent orthographies (Spanish, Slovak, and Czech), kindergarten language skills were another significant predictor of Grade 2 reading comprehension. This effect was absent in the English sample, where variations in decoding skills were a more powerful predictor. These results provide the first longitudinal evidence for effects of orthographic consistency on the development of reading comprehension and provide support for the simple view of reading.     

Longitudinal links between maternal cultural socialization,peer ethnic-racial discrimination,and ethnic-racial pride in Mexican American youth

This paper used cross-lagged panel models to test the longitudinal interplay between maternal cultural socialization, peer ethnic-racial discrimination, and ethnic-racial pride across 5th to 11th grade among Mexican American youth (N = 674, M_age = 10.86; 72% born in the United States; 50% girls; Wave 1 collected 2006–2008). Maternal cultural socialization predicted increases in subsequent youth ethnic-racial pride, and youth ethnic-racial pride prompted greater maternal cultural socialization. However, peer ethnic-racial discrimination was associated with subsequent decreases in ethnic-racial pride. The magnitude of these associations was consistent across 5th to 11th grades suggesting that maternal cultural socialization messages are necessary to maintain ethnic-racial pride across adolescence, thus families must continually support the development of ethnic-racial pride in their youth to counter the effects of discrimination.     

Instructional Activities and the Quality of Language in Chilean Preschool Classrooms

Research Findings: This study examines the association between preschool classroom activity and the quality of the language spoken by teachers and children. Eighteen classrooms serving low-income children between the ages of 3 and 4 in Santiago de Chile were audio-recorded during one morning shift. Recordings were transcribed and segmented into activities (greeting, learning experience, book sharing, book discussion, breakfast, lunch, free play and other noninstructional time). A total of 113 activity segments were identified. Characteristics of teacher and child language were measured in each segment. Differences between the eight activities were examined using analysis of variance. Activities were classified as instructional or noninstructional, and the association between this dimension and language characteristics was examined using multilevel path analysis. Results show that most of the variance in language outcomes occurs within classrooms. Analyses show that a significant portion of the variance in the way teachers and children talk is explained by the instructional/noninstructional dimension. Instructional activities are characterized by more language stimulation, more teaching, fewer directives, and more child talk than noninstructional activities. Practice or Policy Implications: We discuss implications for teacher professional development and early childhood education improvement in general and for Latin-America specifically.     

A tangible landscape modeling system for geography education

Education and Information Technologies - Geography education requires a combination of knowledge, skills, and geospatial relational thinking. To improve the learning efficiency and durability of...