Differences in pedalling technique between road cyclists of different competitive levels     

Juan García-López  Sergio Díez-Leal  Ana Ogueta-Alday  Josu Larrazabal  José A. Rodríguez-Marroyo 《Journal of sports sciences》2016,34(17):1619-1626

The purpose of this study was to compare the pedalling technique in road cyclists of different competitive levels. Eleven professional, thirteen elite and fourteen club cyclists were assessed at the beginning of their competition season. Cyclists’ anthropometric characteristics and bike measurements were recorded. Three sets of pedalling (200, 250 and 300 W) on a cycle ergometer that simulated their habitual cycling posture were performed at a constant cadence (~90 rpm), while kinetic and kinematic variables were registered. The results showed no differences on the main anthropometric variables and bike measurements. Professional cyclists obtained higher positive impulse proportion (1.5–3.3% and P < 0.05), mainly due to a lower resistive torque during the upstroke (15.4–28.7% and P < 0.05). They also showed a higher ankle range of movement (ROM, 1.1–4.0° and P < 0.05). Significant correlations (P < 0.05) were found between the cyclists’ body mass and the kinetic variables of pedalling: positive impulse proportion (r = ?0.59 to ?0.61), minimum (r = ?0.59 to ?0.63) and maximum torques (r = 0.35–0.47). In conclusion, professional cyclists had better pedalling technique than elite and club cyclists, because they opted for enhancing pulling force at the recovery phase to sustain the same power output. This technique depended on cycling experience and level of expertise.  相似文献   

The kinematic differences between off-spin and leg-spin bowling in cricket     

Aaron J. Beach  René E. D. Ferdinands  Peter J. Sinclair 《Sports biomechanics / International Society of Biomechanics in Sports》2016,15(3):295-313

Spin bowling is generally coached using a standard technical framework, but this practice has not been based upon a comparative biomechanical analysis of leg-spin and off-spin bowling. This study analysed the three-dimensional (3D) kinematics of 23 off-spin and 20 leg-spin bowlers using a Cortex motion analysis system to identify how aspects of the respective techniques differed. A multivariate ANOVA found that certain data tended to validate some of the stated differences in the coaching literature. Off-spin bowlers had a significantly shorter stride length (p = 0.006) and spin rate (p = 0.001), but a greater release height than leg-spinners (p = 0.007). In addition, a number of other kinematic differences were identified that were not previously documented in coaching literature. These included a larger rear knee flexion (p = 0.007), faster approach speed (p < 0.001), and flexing elbow action during the arm acceleration compared with an extension action used by most of the off-spin bowlers. Off-spin and leg-spin bowlers also deviated from the standard coaching model for the shoulder alignment, front knee angle at release, and forearm mechanics. This study suggests that off-spin and leg-spin are distinct bowling techniques, supporting the development of two different coaching models in spin bowling.  相似文献   

Perceived health problems in swimmers according to the chemical treatment of water in swimming pools     

Álvaro Fernández-Luna  Pablo Burillo  José Luis Felipe  Julio del Corral  Jorge García-Unanue  Leonor Gallardo 《European Journal of Sport Science》2016,16(2):256-265

The objective of this study was to determine which chemical treatment used for disinfecting water in indoor swimming pools had the least impact on users' perceptions of health problems, and which generated the greatest satisfaction with the quality of the water. A survey on satisfaction and perceived health problems was given to 1001 users at 20 indoor swimming pools which used different water treatment methods [chlorine, bromine, ozone, ultraviolet lamps (UV) and salt electrolysis]. The findings suggest that there is a greater probability of perceived health problems, such as eye and skin irritation, respiratory problems and skin dryness, in swimming pools treated with chlorine than in swimming pools using other chemical treatment methods. Pools treated with bromine have similar, although slightly better, results. Other factors, such as age, gender, time of day of use (morning and afternoon) and type of user (competitive and recreational), can also affect the probability of suffering health problems. For all of the above, using combined treatment methods as ozone and UV, or salt electrolysis produces a lower probability of perceived health problems and greater satisfaction.  相似文献   

Competencies evaluation in engineering programmes     

Mario F. Letelier  José A. Herrera  Andrea M. Canales  Rosario Carrasco  Lorena L. López 《European Journal of Engineering Education》2003,28(3):275-286

Results are reported in this paper from a study aimed at evaluating significant competencies in final-year students of some engineering programmes in Chile. The study was carried out by a group of eight universities that were interested in exploring ways to assess learning outcomes such as those demanded by the recent Chilean accreditation system. The authors actively participated in all stages of the study, contributing directly to the design, application and results evaluation of some tests. A sample of 150 students was tested, under conditions that guaranteed the comparability of results. In this paper the authors present results relating to the evaluation of effective communication. The study was backed up by a conceptual model and some hypotheses that are explained and discussed in this work.  相似文献   

AECT Internship Programs - Developing Leaders for Tomorrow     

J. José Cortez 《TechTrends》2006,50(1):6-8

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Pedro Gutiérrez Bueno’s Textbooks: Audiences, Teaching Practices and Chemical Revolution     

José Ramón Bertomeu Sánchez  Antonio García Belmar 《Science & Education》2006,15(7-8):693-712

Pedro Gutiérrez Bueno wrote two editions of a chemistry textbook between 1788 and 1802. The paper offers a comparative view of both editions taking into account Gutiérrez Bueno’s biography, his intended audience and the changes related to the so-called chemical revolution. Some conclusions are at odds with common images about scientific revolutions and the role of textbooks in science. The analysis aims to shed some light on the multiple historical forces shaping textbooks and the way in which scientific change is assimilated by their writers. This research was partially supported by the program BHA2002-04611-CO3-02  相似文献   

Books and articles of academic interest     

Antonio Gómez Skarmeta  Pedro García López  Jesús Egea Payá  José Meseguer Navarro  Tomás Jiménez García 《Academic Questions》1994,8(1):91-92

Books and articles of academic interest  相似文献   

The second year of life as a developmental turning point: Implications for «sensitive» caretaking     

André Vyt 《European Journal of Psychology of Education - EJPE》1989,4(2):145-158

In the context of the transactional view on development, important changes in the second year of life are highlighted which demand parental adaptations in caregiving practice. The discontinuous growth of enriched cognitive functions in the toddler, as exemplified by Piagetian theory on development of intentionality and symbolic thinking and by recent findings about the emergence of self-awareness and mastery-motivation, meshes with changes in caregiving dimensions. The caregiver, seen as a catalyst for the development of cognitive and social competence must adjust himself to the developmental tasks the infant is coping with. The concept of sensitivity is examined in terms of two important aspects: the social and the didactic. From a Vygotskian standpoint, didactic strategies are very important for cognitive competence. Parents have to facilitate self-initiated learning and to adjust to the infant’s increasing cognitive functions. The influence of a didactic «matching» on overall parent-infant interaction quality, and especially on the quality of attachment, is stressed.  相似文献   

Scaffolding Narrative Skills: A Meta-Analysis of Instruction in Early Childhood Settings     

Diane Pesco  Andréanne Gagné 《Early education and development》2017,28(7):773-793

Research Findings: Children’s ability to tell stories and to understand the stories of others typically emerges in early childhood, supported by primary caregivers and educators. This article reviews instruction designed to foster children’s narrative skills in preschool and kindergarten settings and examines the effects using meta-analysis. The review covers more than 3 decades (1980–2013) of experimental research (k = 15 studies, 28 effects). The findings showed that verbal scaffolding, alone or in combination with other strategies, was the predominant teaching approach. The meta-analysis revealed average effects (weighted for sample size) for narrative expression (.50) and a slightly larger effect for comprehension (.58). These effects were unrelated to the duration of instruction. However, when verbal strategies were combined with nonverbal ones, such as engaging children in enacting stories or in telling stories with props, the effects for expression increased (i.e., children’s storytelling improved more from pretest to posttest). Practice or Policy: The review indicates promising strategies for supporting narrative skills. Furthermore, the studies identified can serve as a resource for practitioners by suggesting diverse kinds of verbal scaffolds, complementary nonverbal approaches, and storybooks that have been used effectively to foster narrative competencies among young children.  相似文献   

The role of student-generated externalizations in strategic multimedia learning and how current (web-)technology fails to support learner engagement     

Rolf Ploetzner  Benjamin Fillisch  Patrick-André Gewald  Tatjana Ruf 《Interactive Learning Environments》2016,24(7):1610-1628

In two studies, we investigated how learning strategies can support learning from multimedia. In the first study, 112 students learned from a web-based learning environment. On the basis of a strategy, one group of students took typewritten notes. The second group of students wrote a summary. Producing typewritten notes did not benefit learning any more than writing a summary. In the second study, 100 students learned the same subject matter from print. On the basis of a strategy, the first group produced written notes, the second group highlighted, wrote notes, and produced sketches. The third group wrote a summary. The students who highlighted, wrote notes, and produced sketches outperformed the other students. The students who produced written notes only did not learn more successfully than those who wrote a summary. The results suggest that externalizations in general and sketches in particular may play an important role in multimedia learning.  相似文献