Kinematical analysis of the V2 ski skating technique: A longitudinal study

To characterise timing of movements and evaluate performance effects of technique alterations in V2 ski skating, 13 elite male cross-country skiers (age, 23 ± 2 years; stature, 182 ± 6 cm; body mass, 76 ± 8 kg; V2 V?O_2max, 79.3 ± 4.4 mL · kg^?1 · min^?1) were tested four times during the preparation and competition phase on a roller ski treadmill. Each test consisted of submaximal intensities of exercise for determination of oxygen cost followed by one 1000-m performance test. Hip movement (from accelerometer data) and joint angles (2D video) were determined for high-intensity exercise (6° and 3.5 m · s^?1; ~ 97–100% of V?O_2peak). Each ski thrust consisted of three phases: gliding phase (18–50% of cycle time), poling phase (50–70% of cycle time), and kick phase (70–78% of cycle time). Flexion/extension of the hip initiated all phases, followed by the respective joints in legs and arms. Mixed-model analysis, adjusting for systematic time-point effects, identified that both reduced vertical hip acceleration and increased cycle time gave a small likely reduction in oxygen cost and 1000-m time. In conclusion, well-developed hip movement is a key characteristic of the V2 technique for elite-standard skiers’ long-term performance development.     

Predicting intentions to perform protective sexual behaviours among Norwegian adolescents

This paper examines the socio‐cognitive processes underlying intentions to use condoms and contraceptive pills, using the Theory of Planned Behaviour extended with prototypes in a group of young Norwegian adolescents. The data are derived from a questionnaire survey comprising all pupils in Grade Nine at three schools in Oslo (n = 196). Using hierarchical multiple regression analyses, the results showed that prototypes and normative beliefs, especially partner's opinion, were the most important predictors for boys' condom decisions. For girls' condom decisions, normative and attitudinal considerations were most important. Perceived risk of getting sexually transmitted diseases was the most important predictor among behavioural beliefs for condom intention for both girls and boys. Normative beliefs, and especially parental opinions, were most important for girls' decisions to use contraceptive pills. Implications of the findings are discussed.     

The Concept of Ideology in Analysis of Fundamental Questions in Science Education

The use of the concept of `ideology' in interpretation of science education curricula, textbooks and various practises is reviewed, and examples are given by referring to Norwegian curricula and textbooks. The term is proposed to be used in a broad sense about any kind of action-oriented theory based on a system of ideas, or any attempt to approach politics in the light of a system of ideas. Politics in this context is about shaping of education, and is related to forces (i.e., hypothetical impacts of idea systems) which may legitimise, change, or criticise social practices. The focus is (although not in every case) on the hidden, unconscious and critical aspects. The notion ideological aspects is proposed to be related to metaphysical-ontological, epistemological and axiological claims and connotations. Examples of educational issues concerning e.g., aims, compartmentalisation, integration, and fundamentally different ideas about truth, learning and man are mentioned. Searching for a single and unifying concept for the discussing of all of science education's fundamental questions seems however in vain. Therefore a wide range of concepts seems necessary to deepen our understanding of ``the fundamental questions'.     

Technique analysis in elite athletes using principal component analysis

The aim of this study was to advance current movement analysis methodology to enable a technique analysis in sports facilitating (1) concurrent comparison of the techniques between several athletes; (2) identification of potentially beneficial technique modifications and (3) a visual representation of the findings for feedback to the athletes. Six elite cross-country skiers, three world cup winners and three national elite, roller ski skated using the V2 technique on a treadmill while their movement patterns were recorded using 41 reflective markers. A principal component analysis performed on the marker positions resulted in multi-segmental “principal” movement components (PMs). A novel normalisation facilitated comparability of the PMs between athletes. Additionally, centre of mass (COM) trajectories were modelled. We found correlations between the athletes’ performance levels (judged from race points) and specific features in the PMs and in the COM trajectories. Plausible links between COM trajectories and PMs were observed, suggesting that better performing skiers exhibited a different, possibly more efficient use of their body mass for propulsion. The analysis presented in the current study revealed specific technique features that appeared to relate to the skiers’ performance levels. How changing these features would affect an individual athlete’s technique was visualised with animated stick figures.     

Data Have No Meaning when Separated from their Context

It is argued that many statisticians teach their subject without much concern about the context in which their methods will be used. This issue is illustrated by the analysis of data on cashier fraud at a supermarket. Here different contexts lead to different questions and different modes of analysis.