Assessing pitcher and catcher influences on base stealing in Major League Baseball

A formal statistical analysis is performed to determine the extent to which pitchers and catchers can influence stolen-base attempts and successes. Two response proportions, attempt/opportunity and success/attempt, are modelled separately using mixed-effects logistic regression models applied to situations with a runner on first and other bases empty. Data include the first innings of all Major League Baseball games played between 1978 and 1990, which encompasses over 48,000 opportunities and 9000 attempts. Pitchers and catchers are entered as random effects and various other factors thought to influence stolen-base attempts and successes are entered as fixed effects. Variance components are estimated and hypotheses tests indicate that the population variance components for both pitchers and catchers are significant for both response proportions. The presence of variation among players at the respective positions is interpreted as evidence that stolen-base defence is a real skill exhibited to varying extents by different players. Furthermore, the variance component for pitchers is greater than that for catchers for both response proportions, indicating that pitchers have greater potential to affect stolen-base attempts and successes. Under usual conditions, it is estimated that 95% of pitchers have first-inning stolen-base success/attempt probabilities between 0.50 and 0.84, while 95% of catchers have probabilities between 0.59 and 0.79.     

Biomechanical comparison of the double-push technique and the conventional skate skiing technique in cross-country sprint skiing

The aims of the study were to: (1) adapt the "double-push" technique from inline skating to cross-country skiing; (2) compare this new skiing technique with the conventional skate skiing cross-country technique; and (3) test the hypothesis that the double-push technique improves skiing speed in a short sprint. 13 elite skiers performed maximum-speed sprints over 100 m using the double-push skate skiing technique and using the conventional "V2" skate skiing technique. Pole and plantar forces, knee angle, cycle characteristics, and electromyography of nine lower body muscles were analysed. We found that the double-push technique could be successfully transferred to cross-country skiing, and that this new technique is faster than the conventional skate skiing technique. The double-push technique was 2.9 +/- 2.2% faster (P < 0.001), which corresponds to a time advantage of 0.41 +/- 0.31 s over 100 m. The double-push technique had a longer cycle length and a lower cycle rate, and it was characterized by higher muscle activity, higher knee extension amplitudes and velocities, and higher peak foot forces, especially in the first phase of the push-off. Also, the foot was more loaded laterally in the double-push technique than in the conventional skate skiing technique.     

A model study of optimal training reduction during pre-event taper in elite swimmers

The aim of this study was to assess responses to taper in elite athletes using computer simulations. Parameters of a non-linear model were derived from training and performance data over two seasons for eight elite swimmers. The fit between modelled and actual performances was statistically significant for each swimmer (r(2) = 0.56 +/- 0.06; P < 0.01). The simulations were used to estimate characteristics of step and progressive tapers that would maximize performance either (1) after regular training only or (2) after overload training of a 20% step increase in regular training for 28 days. The highest performance with a step taper was greater with than without prior overload training (101.4%, s = 1.6 vs. 101.1%, s = 1.4 of personal record; P < 0.01) but required a longer taper duration (22.4 days, s = 13.4 vs. 16.4 days, s = 10.3; P < 0.05). The optimal progressive taper led to a better performance only after the overload period (101.5%, s = 1.5; P < 0.001). Negative and positive influences of training were estimated as indicators of fatigue and adaptations to training respectively. During the optimal taper, the negative influence was completely removed, independently of the prior training, whereas the positive influence increased only after overload training. Our computer simulations show that the characteristics of an optimal training reduction in elite athletes depend on the training performed in the weeks prior to a taper.     

The international face of sports science through the window of the Journal of Sports Sciences--with a special reference to kinanthropometry

The history of the Journal of Sports Sciences is traced from the antecedents of its initiation to the current time. The developments of the sports sciences at large are reflected in the content of the journal. Its links with the international agenda are described, and related to landmark publications. Special attention is given to the relationships with international bodies, the International Society for Advancement of Kinanthropometry and the World Commission of Science and Sports. The expansion of sport and exercise sciences, both nationally and internationally, was reflected in the increased frequency of publication of the journal. Key areas in the kinanthropometric content are identified and placed in context. The review culminates in the highlighting of likely areas for future research.     

Effects of time of day and distance upon accuracy and consistency of throwing darts

We examined variations in dart-throwing performance during the daytime in 12 participants. Two distances from the dartboard were investigated - the normal distance (short throws) and another 50% further away than this (long throws). Intra-aural temperature and subjective fatigue were measured, and errors in performance were assessed as the radial distances of throws from the bulls-eye and the standard deviation of these distances. Long-distance throws improved significantly throughout the daytime and correlated positively with intra-aural temperature (r= -0.49, P=0.002 and r= -0.49, P=0.002 for errors and standard deviation of errors, respectively), but not with subjective fatigue (r= -0.10, P=0.56 and r= -0.05, P=0.74 for errors and standard deviation of errors, respectively). Short-distance throws were associated less with intra-aural temperature (r= -0.46, P= 0.005 and r= -0.17, P=0.31 for errors and standard deviation of errors, respectively), and worsened with fatigue (r=+0.34, P= 0.040 for errors). Compared with the short-distance throws, the long-distance throws were performed significantly less well than could be accounted for by the increased distance (mean errors were increased 1.67-2.78 times and standard deviation of errors of errors 1.58-3.68 times), supporting the concept of a trade-off between force of contraction and accuracy of performance. Throwing darts can be used as a model for investigating factors that influence motor performance, and our results indicate that the effects of time of day upon performance depend upon the relative importance of force and accuracy.     

Schooling for self-employment in Kenya: The acquisition of craft skills in and outside schools

Primary schooling will continue to be the terminal stage of education for most Kenyan children, and it will have to prepare them for employment that they will create for themselves. What this might imply for the teaching of craft skills is examined. Soapstone carving was selected as the subject of study because it is an important form of self-employment in western Kenya. The acquisition of craft skills in and outside schools was compared using observational and experimental methods. It is argued that school instruction provides little opportunity to develop competence in carrying out cognitive and psychomotor tasks important to expert performance in this and perhaps many other craft occupations.     

学校效能的增值评价——对河北省保定市普通高中学校的实证研究

学校评价在教育评价体系中处于核心地位,它直接影响着对教师评价和学生评价的原则以及学校的发展方向。运用增值评价学校效能是当前学校评价研究的重要内容。对河北省保定市普通高中学校效能进行实证研究结果表明60%~80%的高考成绩校际差距都不是学校本身所导致的,在提高学生进步幅度方面,不同学校间存在明显差异。增值评价结果与高考分数评价结果存在较大差异;学校效能在不同学科间没有显著差异;学校对不同学生群体的效能无差异。学校效能的增值评价对于创新学校评价体系具有重要的参考价值。