Impact forces and neck muscle activity in heading by collegiate female soccer players

Three soccer header types (shooting, clearing and passing) and two heading approaches (standing and jumping) were manipulated to quantify impact forces and neck muscle activity in elite female soccer players. The 15 participants were Division I intercollegiate soccer players. Impact forces were measured by a 15-sensor pressure array secured on the forehead. The electromyographic (EMG) activity of the left and right sternocleidomastoid and trapezius muscles was recorded using surface electrodes. Maximum impact forces and impulses as well as the EMG data were analysed with separate repeated-measures analyses of variance. Impact forces and impulses did not differ among the header types or approaches. Higher values were found for jumping versus standing headers in the mean normalized EMG for the right sternocleidomastoid. In addition, the integrated EMG was greater for the right sternocleidomastoid and right and left trapezius (P < 0.05). The sternocleidomastoid became active earlier than the trapezius and showed greater activity before ball contact. The trapezius became active just before ball contact and showed greater activity after ball contact. The increased muscle activity observed in the neck during the jumping approach appears to stabilize the connection between the head and body, thereby increasing the stability of the head-neck complex.     

Manipulating generalized motor program difficulty during blocked and random practice does not affect parameter learning

Blocked practice engenders more trial-to-trial response stability, which is thought to be crucial for developing the generalized motor program (GMP) but not parameter learning (Lai, Shea, Wulf, & Wright, 2000). It was hypothesized that reducing the difficulty of the GMP might permit additional cognitive resources to be allocated to learning the parameter requirements. However, GMP theory maintains the independence of the memories governing the GMP and parameters. This notion suggests that manipulating the difficulty of the GMP should have no effect on the blocked practice participant's ability to successfully specify the appropriate parameters. Participants learned a simple or complex relative timing pattern under either blocked or random practice conditions. Smaller GMP errors were exhibited for the simple relative timing patterns, but this was not associated with improvements in parameter specification following blocked practice. A clear advantage for parameter specification was evident in transfer following random practice. Taken together, these data support the theoretical separation of the GMP and parameter processes.     

Entwicklung gro?er Systeme mit generischen Methoden – Eine übersicht über den Sonderforschungsbereich 501

Ohne Zusammenfassung     

Objektorientierter Entwurf eines flexiblen Workflow-Management-Systems

Zusammenfassung.   Dieser Beitrag enth?lt die wesentlichen konzeptionellen überlegungen zur Entwicklung eines flexiblen Workflow-Management-Systems. Ausgehend von einer Diskussion m?glicher Modellierungsalternativen wird unter Verwendung objektorientierter Modellierungstechniken ein Workflow-Meta-Schema entwickelt, das die relevanten Entit?ten klassifiziert und ihre Beziehungen abbildet. Anhand eines Beispiels werden die getroffenen Entwurfentscheidungen ausführlich begründet. Schlie?lich werden Zust?nde und Zustandsüberg?nge von Workflow-Instanzen beschrieben, und es wird diskutiert, wie dynamische Ver?nderungen von Workflows zur Laufzeit durchgeführt werden k?nnen, um laufende Workflows dynamisch an ver?nderte Umweltbedingungen anzupassen. Eingegangen am 20. Dezember 1997 / Angenommen am 24. Juli 1998     

铅球最佳出手角的计算及其在实践中的应用

运用力学原理,通过数理推导编采了铅球最佳出手角及其射程表,并根据推铅球的运动生物力学特点,分析了理论上最佳出手角及其在实践应用中的局限性,提出理论上的最佳出手角可作为教学训练的定量指标,但并不是竞赛中的最佳出手角,在教学和训练中应结合实际,采用合理的出手角,以利于改进技术,指导训练,提高运动成绩。     

Acute effects of intense interval training on running mechanics

The aims of this study were to determine if there are significant kinematic changes in running pattern after intense interval workouts, whether duration of recovery affects running kinematics, and whether changes in running economy are related to changes in running kinematics. Seven highly trained male endurance runners (VO 2max = 72.3 +/- 3.3 ml kg -1 min -1 ; mean +/- s) performed three interval running workouts of 10 X 400 m at a speed of 5.94 +/- 0.19 m s -1 (356 +/- 11.2 m min -1 ) with a minimum of 4 days recovery between runs. Recovery of 60, 120 or 180 s between each 400 m repetition was assigned at random. Before and after each workout, running economy and several kinematic variables were measured at speeds of 3.33 and 4.47 m s -1 (200 and 268 m min -1 ). Speed was found to have a significant effect on shank angle, knee velocity and stride length (P ? 0.05). Correlations between changes pre- and post-test for VO 2 (ml kg -1 min -1 ) and several kinematic variables were not significant (P > 0.05) at both speeds. In general, duration of recovery was not found to adversely affect running economy or the kinematic variables assessed, possibly because of intra-individual adaptations to fatigue.     

General Media and Society

Atwan, Robert, Barry Orton, and Alliam Vesterman. American Mass Media: Industries and Issues (New York: Random House, 1978—$8.95, paper)

Dennis, Everette E., Arnold H. Ismach, and Donald M. Gillmor, eds. Enduring Issues in Mass Communication (St. Paul, Minn.: West P.' _fishing Co., 1978—price not given, paper)

White, David Manning, and John Pendleton, eds. Popular Culture: Mirror of American Life (Del Mar, Calif.: Publisher's Inc., 1977—$11.95/6.25)

Charlene J. Brown, Trevor R. Brown, and William L. Rivers' The Media and the People (New York: Holt, Rinehart a Winston, 1978 —price not given, paper)

Malcolm Muggeridge's Christ and the Media (Grand Rapids, Mich.: William B. Eerdmans Publishing Co., 1977— $5.95)     

Understanding How the Arts Can Enhance Learning

Understanding how the arts can enhance learning has long been discussed and debated among educators, students, parents, artists, art historians, and philosophers. Many anecdotal examples reference the value and benefits of the arts in a range of fields and learning domains. Emerging methodologies in the brain sciences have added new perspectives and research‐based approaches to better understand the role the arts might play in learning. Psychologists, cognitive scientists, and now neuroscientists are approaching this topic by exploring memory, sensory systems, and other biological measures. The interdisciplinary and potentially interdependence of these fields to work together to identify the neurological mechanisms involved in the arts may offer educators, parents, and child care providers with important information about how we learning takes place. By bringing together uncommon and divergent thinking from a wide range of disciplines, there is an opportunity to change the way we teach, parent, and serve children using the arts to help enhance learning. This issue of Mind, Brain, and Education celebrates the range of approaches that are emerging to shed light and insight in this field.