Physiological demands of top-class soccer refereeing in relation to physical capacity: effect of intense intermittent exercise training

To examine the activity profile and physiological demands of top-class soccer refereeing, we performed computerized time-motion analyses and measured the heart rate and blood lactate concentration of 27 referees during 43 competitive matches in the two top Danish leagues. To relate match performance to physical capacity and training, several physiological tests were performed before and after intermittent exercise training. Total distance covered was 10.07 - 0.13 km (mean - s x ), of which 1.67 - 0.08 km was high-intensity running. High-intensity running and backwards running decreased (P ? 0.05) in the second half. Mean heart rate was 162 - 2 beats· min -1 (85 - 1% of maximal heart rate) and the mean blood lactate concentration was 4.9 - 0.3 (range 1.7-14.0) mmol·l -1 . The amount of high-intensity running during a match was related to the Yo-Yo intermittent recovery test ( r 2 = 0.57; P ? 0.05) and the 12 min run ( r 2 = 0.21; P ? 0.05). After intermittent training ( n = 8), distance covered during high-intensity running was greater (2.06 - 0.13 vs 1.69 - 0.08 km; P ? 0.05) and mean heart rate was lower (159 - 1 vs 164 - 2 beats· min -1 ; P ? 0.05) than before training. The results of the present study demonstrate that: (1) top-class soccer referees have significant aerobic energy expenditure throughout a game and episodes of considerable anaerobic energy turnover; (2) the ability to perform high-intensity running is reduced towards the end of matches; (3) the Yo-Yo intermittent recovery test can be used to evaluate referees' match performance; and (4) intense intermittent exercise training improves referees' performance capacity during a game.     

Creatine kinase,myosin heavy chains and magnetic resonance imaging after eccentric exercise

The aim of this study was to examine the relationship between myosin heavy chain (MHC) release as a specific marker of slow-twitch muscle fibre breakdown and magnetic resonance imaging (MRI) of skeletal muscle injury after eccentric exercise. The effects of a single series of 70 high-intensity eccentric contractions of the quadriceps femoris muscle group (single leg) on plasma concentrations of creatine kinase and MHC fragments were assessed in 10 young male sport education trainees before and 1 and 4 days after exercise. To visualize muscle injury, MRI of the loaded thigh was performed before and 4 days after the eccentric exercise. All participants recorded an increase ( P ? 0.05) in creatine kinase after exercise. In five participants, T2 signal intensity was unchanged post-exercise compared with pre-exercise and MHC plasma concentration was normal; however, they showed an increase ( P ? 0.05) in creatine kinase after exercise. For the remaining five participants, there was an increase in T2 signal intensity of the loaded vastus intermedius and vastus lateralis. These changes in MRI were accompanied by an increase in MHC plasma concentration ( P ? 0.01) as well as an increase in creatine kinase ( P ? 0.01). We suggest that changes in MRI T2 signal intensity after muscle damage induced by eccentric exercise are closely related to damage to structurally bound contractile filaments of some muscle fibres. Additionally, MHC plasma release indicates that this damage affects not only fast-twitch fibres but also some slow-twitch fibres.     

A citation and co-citation analysis of 10 years of KM theory and practices

In a previous issue of Knowledge Management Research & Practice (KMRP), we analysed the content and keywords of all articles published in the first decade of KMRP. With this article, we extend our preliminary analysis to the citation and co-citations made by these articles. The study covers all the 256 articles published. The most cited article was A dynamic theory of organisational knowledge creation by Nonaka. The most cited KMRP article was by Nonaka and Toyama: The knowledge-creating theory revisited: knowledge creation as a synthesizing process. The co-citation analysis of the 100 most cited articles in KMRP publications showed that four groups of topics emerged, one around communities and situated learning, the second group around networks, knowledge transfer and research methods, a third group around the foundations of knowledge management and a fourth group around intellectual capital.     

Cardiac Structure and Function in Women Basketball Athletes: Seasonal Variation and Comparisons with Nonathletic Controls

Abstract

To characterize hypertrophy and quantify seasonal changes in cardiac structure and function of women collegiate basketball (BB) athletes (n = 15), echocardiography (echo) measurements were made in the fall (FALL₁), winter (WIN), and spring (SPR), then again during the subsequent fall (FALL₂; n = 10). Comparisons were made to age-matched nonathletes (NA) measured during FALL₁ (n = 22) and SPR (n = 5). Left ventricular (LV) internal dimension–diastole (LVIDd), LV end-diastolic volume (LVEDV), stroke volume (SV), LV mass (LVM), septal thickness (IVS), LV posterior wall thickness (LVPW), right ventricular (RV) internal dimension-diastole (RVIDd), and aortic root diameter (AOD) were significantly larger (12–70%) in the athletes; RVIDd-, LVEDV-, SV-, and LVM-index were also significantly greater (8–46%). From FALL₁ to SPR measurement periods, LVWd, RVWd, LVEDV, SV, IVS, and LVM-index increased significantly (7–18%) in the athletes. Over the same period of time, LVIDd, LAD, AOD, LVEDV, and SV measured in the five NA subjects increased significantly. In the athletes, LVIDs, RVIDd, IVS, LVPW, and LVM decreased significantly (5–30%) from the SPR to FALL₂ measurement period. These data characterize the general nature of the cardiac hypertrophy noted in women BB athletes compared to NA controls and show that distinct changes in heart structure corresponding to different periods of the competitive season can occur in these athletes.     

The relevance of innovative school architecture for school principals

In many cases, innovative forms of learning require innovative concepts of using space in school. However, so far there has been a lack of research concerning the perspectives of school principals as important stakeholders in the adoption of alternative school architecture. The present study examines the importance of alternative school architecture in a sample of 1164 principals (56% females, mean-age 52.7 years) in Austria. An online questionnaire was conducted, containing questions about the school building, innovative forms of learning, and principals’ level of information, perceptions, and thoughts on the relevance of school architecture, as well as their motivation and self-efficacy. Results showed that principals are aware of the advantages of certain architectural elements, although these elements have been implemented in only a few schools. A high proportion of respondents report a lack of information about configurations of space that go beyond the traditional corridor-scheme. We conclude that although principals are in general open for the alternative configuration of space further efforts have to be made to overcome the obstacles that prevent principals from launching new concepts of using space, which are a lack of competitive resources and knowledge as well as an inadequate professional network.     

Young people’s mental health: Exploring the gap between expectation and experience

ABSTRACT

Background

The proportion of young people suffering from poor mental health is on the increase, including in Scandinavian countries. This increase seems paradoxical, as Scandinavian countries are among those with the lowest degree of material deprivation, economic inequality, and social exclusion.     

Learning oceanography from a computer simulation compared with direct experience at sea

Considerable research has compared how students learn science from computer simulations with how they learn from “traditional” classes. Little research has compared how students learn science from computer simulations with how they learn from direct experience in the real environment on which the simulations are based. This study compared two college classes studying introductory oceanography. One class learned using an interactive computer simulation based on a dynamic, three‐dimensional model of physical oceanography. The other class learned by spending a day on a research ship using scientific tools and instruments to measure physical properties of the ocean directly. In classes preceding and following the simulation or field experience, students performed the same exercises regarding currents and salinity, had the same instructor presentations, and did the same homework. The study found that the field experience helped contextualize learning for students with little prior experience of the ocean while the simulation made it easier for students to connect what they learned from it to other content they learned in class. These and other findings shed light on what computer simulations can and cannot help students learn, and what concepts are best learned in the real environment. © 2005 Wiley Periodicals, Inc. J Res Sci Teach 43: 25–42, 2006     

Academic Functioning and Peer Influences: A Short‐Term Longitudinal Study of Network–Behavior Dynamics in Middle Adolescence

In this study, the associations between peer effects and academic functioning in middle adolescence (N = 342; 14–15 years old; 48% male) were investigated longitudinally. Similarity in achievement (grade point averages) and unexplained absences (truancy) was explained by both peer selection and peer influence, net of acceptance, and connectedness. Friendships were formed and maintained when adolescents had low levels of achievement or high levels of truancy. Friends influenced one another to increase rather than decrease in achievement and truancy. Moreover, friends’ popularity moderated peer influences in truancy in reciprocal friendships but not in unilateral friendships, whereas friends’ acceptance moderated peer influences in achievement in both unilateral and reciprocal friendships. The findings illustrate the dynamic interplay between peer effects and academic functioning.