Elite football on artificial turf versus natural grass: movement patterns, technical standards, and player impressions

The aim of the present study was to examine the movement patterns, ball skills, and the impressions of Swedish elite football players during competitive games on artificial turf and natural grass. Time - motion analyses (36 observations) and technical analyses (16 team observations) were performed and 72 male and 21 female players completed a questionnaire. No differences were observed between artificial turf and natural grass in terms of total distance covered (mean 10.19 km, s = 0.19 vs. 10.33 km, s = 0.23), high-intensity running (1.86 km, s = 0.10 vs. 1.87 km, s = 0.14), number of sprints (21, s = 1 vs. 22, s = 2), standing tackles (10, s = 1 vs. 11, s = 1) or headers per game (8, s = 1 vs. 8, s = 1), whereas there were fewer sliding tackles (P < 0.05) on artificial turf than natural grass (2.1, s = 0.5 vs. 4.3, s = 0.6). There were more short passes (218, s = 14 vs. 167, s = 12) and midfield-to-midfield passes (148, s = 11 vs. 107, s = 8) (both P < 0.05) on artificial turf than natural grass. On a scale of 0-10, where 0 = "better than", 5 = "equal to", and 10 = "worse than", the male players reported a negative overall impression (8.3, s = 0.2), poorer ball control (7.3, s = 0.3), and greater physical effort (7.2, s = 0.2) on artificial turf than natural grass. In conclusion, the running activities and technical standard were similar during games on artificial turf and natural grass. However, fewer sliding tackles and more short passes were performed during games on artificial turf. The observed change in playing style could partly explain the male players' negative impression of artificial turf.     

Relationships among values, achievement orientations, and attitudes in youth sport

This research examines the value-expressive function of attitudes and achievement goal theory in predicting moral attitudes. In Study 1, the Youth Sport Values Questionnaire (YSVQ; Lee, Whitehead, & Balchin, 2000) was modified to measure moral, competence, and status values. In Study 2, structural equation modeling on data from 549 competitors (317 males, 232 females) aged 12-15 years showed that moral and competence values predicted prosocial attitudes, whereas moral (negatively) and status values (positively) predicted antisocial attitudes. Competence and status values predicted task and ego orientation, respectively, and task and ego orientation partially mediated the effect of competence values on prosocial attitudes and of status values on antisocial attitudes, respectively. The role of sport values is discussed, and new research directions are proposed.     

Effects of muscle-tendon length on joint moment and power during sprint starts

The aim of this study was to examine the effects of muscle-tendon length on joint moment and power during maximal sprint starts. Nine male sprinters performed maximal sprint starts from the blocks that were adjusted either to 40 degrees or 65 degrees to the horizontal. Ground reaction forces were recorded at 833 Hz using a force platform and kinematic data were recorded at 200 Hz with a film camera. Joint moments and powers were analysed using kinematic and kinetic data. Muscle - tendon lengths of the medial gastrocnemius, soleus, vastus medialis, rectus femoris and biceps femoris were calculated from the set position to the end of the first single leg contact. The results indicated that block velocity (the horizontal velocity of centre of mass at the end of the block phase) was greater (P < 0.01) in the 40 degrees than in the 65 degrees block angle condition (3.39 +/- 0.23 vs. 3.30 +/- 0.21 m . s(-1)). Similarly, the initial lengths of the gastrocnemius and soleus of the front leg in the block at the beginning of force production until half way through the block phase were longer (P < 0.001) in the 40 degrees than in the 65 degrees block angle condition. The initial length and the length in the middle of the block phase were also longer in the 40 degrees than in the 65 degrees block angle condition both for both the gastrocnemius (P < 0.01) and soleus (P < 0.01-0.05) of the rear leg. In contrast, the initial lengths of the rectus femoris and vastus medialis of the front leg were longer (P < 0.05) in the 65 degrees than in the 40 degrees block angle condition. All differences gradually disappeared during the later block phase. The peak ankle joint moment (P < 0.01) and power (P < 0.05) during the block phase were greater in the 40 degrees than in the 65 degrees block angle condition for the rear leg. The peak ankle joint moment during the block phase was greater (P < 0.05) in the 40 degrees block angle for the front leg, whereas the peak knee joint moment of the rear leg was greater (P < 0.01) in the 65 degrees block angle condition. The results suggest that the longer initial muscle-tendon lengths of the gastrocnemius and soleus in the block phase at the beginning of force production contribute to the greater peak ankle joint moment and power and consequently the greater block velocity during the sprint start.     

Teachers' perspectives on the challenges of teaching physical education in urban schools: the student emotional filter

The purpose of this study was to analyze how the challenges of urban schools influence physical education teachers' emotional understanding and connections with their students and the implications on their teaching. Sixty-one elementary physical educators from an urban school district in the midwestern U.S. were interviewed multiple times (N = 136) over 3 years using interpretive methodology. Teachers reported five unique challenges that significantly shaped their thinking about students and their careers, along with strategies they used to overcome or manage those challenges. The challenges were: (a) insufficient instructional resources, (b) implementing culturally relevant pedagogy, (c) dealing with community violence, (d) integrating more games in curricula, and (e) teaching in a culture of basketball. Implications centered on the guilt-inducing nature of urban teaching, developing an informed and realistic vision of urban physical education, and the role of teacher preparation and professional development.     

Climate control through ionization

This paper summarizes some of the experimental evidence of the apparent biological effects produced by atmospheric ionization. Thermionic ion sources are discussed and the results of experimental determinations of their characteristics are presented.     

On stochastic differential equations with non-white noise having small correlation times

This is an extension of an earlier paper by the second author. In the previous work, an algorithm was derived for the moments of an homogeneous equation with noise similar to the white noise, but has small, finite correlation time. In the present work this algorithm is extended for an inhomogeneous equation with the same characteristics. Previous notation has been kept throughout the paper.     

Das Pädagogische Konzept Maria Montessoris: Die Permanente Diskussion

This article emphasises the internal consistency of Maria Montessori's work by identifying her main educational ideas and clarifying the interrelationships between the individual experimental schools and her writings. An elucidation of the vital part played by the anthropological basis of Maria Montessori's work shows that her entire efforts were directed towards illuminating childhood as the foundation of human development. Within this framework her relationship to Rousseau on the one hand, and to educational reform trends on the other is brought out. It is in this connection that her relations with the World Education Fellowship in general and with Decroly in particular find their significance.