Knee angular displacement and extensor muscle activity in telemark skiing and in ski-specific strength exercises

Much of the training of competitive telemark skiers is performed as dry-land exercises. The specificity of these exercises is important for optimizing the training effect. Our aim here was to study the activation of the knee extensor musculature and knee angular displacement during competitive telemark skiing and during dry-land strength training exercises to determine the specificity of the latter. Specificity was analysed with respect to angular amplitude, angular velocity, muscle action and electromyographic (EMG) activity. Five male telemark skiers of national and international standard volunteered to participate in the study, which consisted of two parts: (1) skiing a telemark ski course and (2) specific dry-land strength training exercises for telemark skiing (telemark jumps and barbell squats). The angular displacement of the right knee joint was recorded with an electrogoniometer. A tape pressure sensor was used to measure pressure between the sole of the foot and the bottom of the right ski boot. Electromyographic activity in the right vastus lateralis was recorded with surface electrodes. The EMG activity recorded during maximum countermovement jumps was used to normalize the EMG activity during telemark skiing, telemark jumps and barbell squats. The results showed that knee angular displacement during telemark skiing and dry-land telemark jumps had four distinct phases: a flexion (F1) and extension (E1) phase during the thrust phase of the outside ski/leg in the turn/jump and a flexion (F2) and extension (E2) phase when the leg was on the inside of the turn/jump. The vastus lateralis muscle was activated during F1 and E1 in the thrust phase during telemark skiing and telemark jumps. The overall net knee angular amplitude was significantly greater (P < 0.05) for telemark jumps than for telemark skiing. Barbell squats showed a knee angular amplitude significantly greater than that in telemark skiing (P < 0.05). The mean knee angular velocity of the F1 and E1 phases during telemark skiing was about 0.47 rad x s(-1); during barbell squats, it was about 1.22 rad x s(-1). The angular velocity during telemark jumps was 2.34 and 1.59 rad x s(-1) in the F1 and E1 phase, respectively. The normalized activation level of the EMG bursts during telemark skiing, telemark jumps and barbell squats was 70-80%. In conclusion, the muscle action and level of activation in the vastus lateralis during the F1 and E1 phases were similar during telemark skiing and dry-land exercises. However, the dry-land exercises showed a larger knee extension and flexion amplitude and angular velocity compared with telemark skiing. It appears that an adjustment of knee angular velocity during barbell squats and an adjustment of knee angle amplitude during both telemark jumps and barbell squats will improve specificity during training.     

Work-time profile,blood lactate concentration and rating of perceived exertion in the 1998 Greco-Roman Wrestling World Championship

The aim of this study was to examine work-time profiles, blood lactate concentrations and perceived exertion among Greco-Roman wrestlers in the 1998 World Championship. Forty-two senior wrestlers from nine nations were studied in 94 matches. Each match was recorded with a video camera (Panasonic AG 455, film rate: 25 Hz) and analysed for duration of work (wrestling) and rest (interrupt) periods. Blood lactate concentration was determined with an electrochemical device (Analox P-LM5) and a rating of perceived exertion scale (Borg) was used to estimate general exertion and exertion in the extremity and trunk muscles. The mean duration of the matches was 427 s (range 324-535 s), with mean durations of work and rest of 317 and 110 s, respectively. The mean periods of work and rest were 37.2 and 13.8 s, respectively. Mean blood lactate concentration was 14.8 mmol x 1(-1) (range 6.9-20.6). The difference in mean blood lactate concentration between the first- and final-round matches was not significant (P > 0.05). Blood lactate concentration was significantly higher (P < 0.04) in matches of long duration than in those of short duration. The mean general rating of perceived exertion for all matches was 13.8 according to the scale used. Most of the wrestlers (53.3%) perceived exertion to be highest in the flexors of the forearm, followed by the deltoids (17.4%) and the biceps brachii muscles (12.0%). In addition to a relatively high rating of perceived exertion in the arm muscles, this indicates a high specific load on the flexor muscles of the forearm.     

Physical requirements in Olympic sailing

Abstract

Physical fitness and muscular strength are important performance parameters in Olympic sailing although their relative importance changes between classes. The Olympic format consists of eight yacht types combined into 10 so-called events with total 15 sailors (male and female) in a complete national Olympic delegation. The yachts have different requirements with respect to handling, and moreover, each sailor plays a specific role when sailing. Therefore physical demands remain heterogeneous for Olympic sailors. Previous studies have mainly examined sailors where ‘hiking’ (the task of leaning over the side of the yacht to increase righting moment) is the primary requirement. Other than the ability to sustain prolonged quasi-isometric contractions, hiking seems to require significant maximal muscle strength especially in knee extensors, hip flexors and abdominal and lower back muscles. Another group of studies has investigated boardsailing and provided evidence to show that windsurfing requires very high aerobic and anaerobic capacity. Although data exist on other types of sailors, the information is limited, and moreover the profile of the Olympic events has changed markedly over the last few years to involve more agile, fast and spectacular yachts. The change of events in Olympic sailing has likely added to physical requirements; however, data on sailors in the modern-type yachts are scarce. The present paper describes the recent developments in Olympic sailing with respect to yacht types, and reviews the existing knowledge on physical requirements in modern Olympic sailing. Finally, recommendations for future research in sailing are given.     

Negotiated silence: the management of the self as a moral subject in young Ethiopian women's discourse about sexuality

In Ethiopia, as in many other countries, moral discourses about female sexuality in general, and pre- and extramarital sexual experience in particular, create an environment that discourages women from engaging in open dialogue about their sexuality and their past or future sexual experience. In the study of induced abortion among unmarried women in Addis Ababa on which this paper rests, women describe a situation in which they are both surrounded by silence about sexual issues and forced to remain silent themselves. This paper investigates the nature of, and conditions for, this silence and the ways in which it is socially brought about and negotiated. In particular, it explores the ways through which young, unmarried women who have undergone abortion seek to reconcile seemingly contradictory, condemning discourses about premarital sex and more general codes addressing social, as well as moral, propriety and integrity. The discussion highlights that, while issues of sexuality are silenced, neither the silence nor the silencing power of dominant, gendered moral discourses is absolute. Moreover, silence may also be jointly produced and negotiated in social discourse fraught with moral objectives and ends.     

Engaging youth of color in applied science education and public health promotion

Participation in inquiry-based science education, which focuses on student-constructed learning, has been linked to academic success. Whereas the benefits of this type of science education are evident, access to such high-quality science curriculum and programming is not equitable. Black and Latino students in particular have less access to supplementary science programming, and fewer opportunities to engage in inquiry-based education. This paper describes outcomes associated with an inquiry-based out-of-school time science education program, Nuestro Futuro: Applied Science Education to Engage Black and Latino Youth (NFASE), which sought to build the capacity of middle school students of color to ‘think’ like health scientists from diverse disciplinary perspectives. The program was designed with the intent of (1) improving student attitudes toward and motivation for science and (2) increasing active and engaged citizenship (AEC). NFASE students explored health inequity and the social determinants of health locally and engaged in developing health promotion, outreach and education efforts targeted to their peers, parents/families, and community. Interest in the program was high overall, but implementation was not without challenges. Although evaluation outcomes indicate that there were no statistically significant changes in science-related attitudes or motivation, students reported significant increases in neighborhood social connection, as well as overall AEC.     

A generic method for distribution and transfer of ECTS and other norm-referenced grades within student cohorts

The ECTS grade transfer scale is an interface grade scale to help European universities, students and employers to understand the level of student achievement. Hence, the ECTS scale can be seen as an interface, transforming local scales to a common system where A–E denote passing grades. By definition, ECTS should distribute the passing students into five cohorts representing fixed percentiles. This paper presents a generic method to distribute cohorts of students with differentiated passing local grades into ECTS, or any other grading scale, cohorts. It takes into account historic student performance, the percentiles required for the scale in question as well as the relative performance of a student group in relation to student groups previously graded in the same course module. This method can handle any number of equally or unequally spaced local grade cohorts of any size, and it allows direct transfer between local grades in the spirit of ECTS.     

Socialization content in schools and education for sustainable development – I. A study of teachers’ selective traditions

This article studies content issues by examining teachers’ communicated socialization content. The value-laden socialization content constitutes the educational context for the teaching of integrated subject matter and has not yet been thoroughly studied empirically in environmental education research. The implications of the results can be fruitful in discussions about how educational traditions evolve, as well as discussions about the relationships between environmental education (EE) and education for sustainable development (ESD). In this study, ten upper secondary teachers are interviewed and their expressed socialization content is examined. Various qualitative positions regarding five important educational aspects can be described in terms of three selective traditions. To strengthen the validity of the socialization content found in this study, the students of the same teachers were interviewed regarding their experiences of the socialization content of these teachers’ teaching. This is reported in a supplementary article (Sund and Wickman 2011; Sund 2008). Together these three studies (this article; Sund and Wickman 2011; Sund 2008) work to establish and test a method of discerning qualitative aspects in socialization content. Although the amount of data is limited, the ambition has been to triangulate socialization content qualitatively from three different sources: a literature study, teacher interviews, and student interviews.