Comparisons of the ski turn techniques of experienced and intermediate skiers

We compared selected kinematic variables for four different ski turn techniques performed by five experienced and five intermediate male skiers. The four ski turn techniques were the upstem turn, the downstem turn, the parallel turn and the parallel step turn. Each turn was divided into the initiation phase and the first and second steering phases. Most of the statistically significant differences (P < 0.05) between the two groups were found for the initiation phases of the four turns. Both the hip axis-hand axis angle and the edging angle of the uphill ski were significantly different between the two groups for the upstem turn at the beginning of the initiation phase. For the downstem turn, significant differences between the groups were found at the start of the initiation phase for the hip axis-hand axis angle, the shoulder axis-fall line angle, and the edging angle of the uphill ski. The standard deviation of the distance between the tips of the two skis over the second steering phase also differed significantly between the two groups. For the parallel step turn, significant differences were found at the start of the initiation phase for the edging angle of the downhill ski and the downhill ski to movement direction angle. Significant differences were also found for the edging angle of the downhill ski in the middle of the second steering phase and the shoulder axis to movement direction angle at the end of this phase. For the initiation phase of the parallel turn, significant differences were found for the timing of setting the ski pole, the uphill knee angle at the start of this phase and the range of the knee angle of the uphill leg from the start to the end of this phase. For this turn, significant differences between the two groups were also found for the edging angle of the downhill ski in the middle of the second steering phase and the shoulder axis to movement direction angle at the end of this phase. One of the reasons it was possible to identify a few significant differences only for the turns analysed, was the variability within the intermediate group: for most of the variables analysed, the standard deviation was much higher for the intermediate than for the experienced group.     

The effects of increased shooting distance in the basketball jump shot

Three‐dimensional video techniques (50 Hz) were used to obtain images of basketball jump shots from one of three distances ‐ short range (group 1, n = 5); medium range (group 2, n = 5); long range (group 3, n = 5) ‐ from the basket, as performed by members of the men's quarter‐finalist teams at the games of the XVI Universiade in Sheffield in 1991. Fifteen sequences were digitized, beginning 20 frames prior to take‐off to 10 frames after release. To facilitate analysis, the sequences were rotated about the ball position in the final frame so that the shot direction was parallel to one of the pre‐defined orthogonal axes.

Mean (+1 s.d.) ball release speed was found to increase with distance from the basket (group 1 = 3.04±0.65 m s‐¹, group 2 = 4.71+0.74 m s‐¹, group 3 = 6.24 + 0.80 m s‘¹), while mean release angles were similar for all groups (group 1=48.8 + 10.1°, group 2 = 47.8 + 5.8°, group 3 = 51.9 + 5.5°). The increased impulse necessary for the ball to reach the basket at increased shooting distances was derived from both an increase in angular velocity of the elbow joint of the shooting arm and an increased velocity of the centre of mass in the direction of the basket at release. Centre of mass speed at take‐off was found to be influenced to a greater extent by the angular velocity of the ankle joint than that of the knee or hip joints. Rotation of the hip and shoulder axes, facilitated by the forward placement of the foot on the side of the shooting arm (antero‐posterior separation values: group 1 = 0.17 + 0.11 m, group 2 = 0.10 + 0.14 m, group 3 = 0.09 + 0.09 m) was utilized by all except one subject. All subjects also used an amount of medio‐lateral foot separation which, along with antero‐posterior separation, promoted stability.

All the subjects released the ball while airborne. Both the maximum jump height and the height of the jump at release tended to decrease as shooting distance increased. For short‐range shots, release occurred after the peak of the jump, but increasingly prior to the peak as shooting distance increased.     

Estimating propulsive forces in swimming from three‐dimensional kinematic data

Propulsive forces are important determinants of swimming performance. The aim of this study was to quantify the measurement error (uncertainty) in propulsive forces calculated from kinematic data. Ten operators digitized underwater video recordings of a breaststroke swimmer's right arm action. Four landmarks on the hand were digitized at 50 Hz and their three‐dimensional coordinates obtained using a DLT algorithm. Two angles (α and ψ) defining the orientation of the hand relative to the fluid flow were calculated following the procedures of Schleihauf et al. (1983). The hydrodynamic force acting on the hand (F _R) was calculated using the force coefficients of Schleihauf (1979). Errors in single measurements of hand speed, α and ψ were estimated for each video field analysed. Errors in α and ψ led to average errors in the lift and drag coefficients of 27 and 20% respectively, which, when combined with an average hand speed error of 6%, produced an average error in F _R of 26%. Each of these errors was reduced by a factor of √10 when the mean of 10 measurements was used to calculate F _R . Researchers should report both the estimated errors in their hydrodynamic data and the procedures used to reduce them.     

Corporate federalism and the reform of teacher education in Australia

Current Australian commitments to competency‐based teacher reforms have wide acceptance. The key to this has been the affirmative stance adopted by the peak education unions and by ‘progressive’ educationalists, the nominal guarantors of recent professional advances in teaching. Since Australian approaches to ‘competencies’ are part of a more general agenda of industrialization of education, what is clearly indicated are radical changes in the way that nominally independent/critical language of education is currently being interpreted and applied: this is now being used to support an overall restructuring in which substantive (professional) forms of teacher authority are being uncompromisingly targeted. The transformations identified in this paper as having special strategic significance involve the themes of ‘school as community’ and ‘critical practice’. These have been detached from their traditional (robustly anti‐industrial) reference points and redeployed to authorize a more active (because supposedly conflict‐free) regulatory role by newly empowered managers and to advance the claim that ‘the practical’, on its own, can now be revalorized to allow real scope for creative and contextualized interventions by teachers. A strictly managerialist/technicist perspective upon schooling is thus represented as occupying the highest moral and cognitive ground. Correspondingly ruled out is the case for any real measure of educational pluralism or leamercentredness, no matter the sociocultural complexities, thereby licensing the extension to the school site itself of direct (educationally unmediated) political controls over education. As its counterpoint to the new agenda, this paper stresses the need for a robust decision‐making role by educators at all levels of policy formation, and for learner‐centred interventions which are much more than technical, whatever the processes of revalorization supposedly at work.     

Qualitative research in Australia

Qualitative educational research in Australia has been characterized since the early 1970s by vitality and interest in reconstructing in cultural terms the best research practices, particularly those observed in the UK and USA. The former's influence is best demonstrated in case study method and participatory action research in the 1980s. Australian qualitative educational sociology, drawing on critical theoretical methods, continues to command strong international respect. More recently, post‐structuralist theory has influenced many approaches to qualitative inquiry, especially in feminist research, which reflects a more globalized view of research. Whatever theoretical and methodological directions Australian qualitative enquiry takes in the later 1990s, research must address political and economic contexts of change both nationally and globally if it is to make a difference.     

SATs for Some but Not for All?

How did pupils with special educational needs and their teachers tackle this year's first full run of SATs at Key Stage 1? David Bartlett, senior psychologist, Birmingham Education Authority, was previously coordinator for special needs and bilingualism working with the writing team for Key Stage 1 SATs, Consortium for Assessment and Testing in Schools. He comments on Birmingham schools' experiences with SATs and proposes improvements.     

Mechanical behaviour of natural turf sports pitches across a season

A study assessing the mechanical behaviour of six natural turf pitches of varying sporting level and surface construction was undertaken over a period of 10?months, spanning a sporting season (August 2010 to May 2011). Penetration resistance and shear resistance were measured with the GoingStick^?, impact hardness and surface energy absorption were measured with the 2.25?kg Clegg Impact Soil Tester and the Dynamic Surface Tester device, respectively. The two sand rootzone pitches were more resistant to deformation and less variable in their impact behaviour (impact hardness and energy absorption) through the season than the native soil pitches containing greater proportions of silt and clay. Greater consistency was shown for penetration resistance and shear resistance on one of the sand rootzone pitches, with the other behaving similar to the native soil pitches for these parameters. The sand rootzone surfaces exhibited greater (P?<?0.05) impact hardness than the native soil pitches in the winter period of the season (November to mid-March) compared to the beginning or end periods of the season, where data were statistically similar (P?>?0.05). The greater consistency of sand rootzone surfaces should be considered for the effect it may have on player and team performance, and injury potential. Analysis of data against Performance Quality Standard benchmarks indicated that all data on the sand rootzones exceeded preferred values for impact hardness, indicating these ranges may be obsolete for the modern elite natural turf surface.     

Differential training loads and individual fitness responses to pre-season in professional rugby union players

We aimed to compare differentiated training loads (TL) between fitness responders and non-responders to an eight-week pre-season training period in a squad of thirty-five professional rugby union players. Differential TL were calculated by multiplying player’s perceptions of breathlessness (sRPE-B) and leg muscle exertion (sRPE-L) with training duration for each completed session. Performance-based fitness measures included the Yo-Yo Intermittent Recovery Test Level 1 (YYIRTL1), 10-, 20-, and 30-m linear sprint times, countermovement jump height (CMJ) and predicted one-repetition maximum back squat (P1RM Squat). The proportion of responders (≥ 75% chance that the observed change in fitness was > typical error and smallest worthwhile change) were 37%, 50%, 52%, 82% and 70% for YYIRTL1, 20/30-m, 10-m, CMJ and P1RM Squat, respectively. Weekly sRPE-B-TL was very likely higher in YYIRTL1 responders (mean difference = 18%; ±90% confidence limits 11%), likely lower in 20/30-m (19%; ±20%) and 10-m (18%; ±17%) responders, and likely higher in CMJ responders (15%; ±16%). All other comparisons were unclear. Weekly sRPE-B discriminate between rugby union players who respond to pre-season training when compared with players who do not. Our findings support the collection of differential ratings of perceived exertion and the use of individual response analysis in team-sport athletes.