Cross‐Country Skiing

The purpose was to study the adaptation to speed in the temporal patterns of the movement cycle and determine any differences in velocity, cycle rate and cycle length at the maximum speed level in the different classical style and freestyle cross‐country skiing techniques. Eight skilled male cross‐country skiers were filmed with a digital video camera in the sagittal plane while skiing on a flat cross‐country ski track. The skiers performed three classical style techniques the diagonal stride, kick double poling and the double poling technique and four freestyle techniques paddle dance (gear 2), double dance (gear 3), single dance (gear 4) and combiskate (gear 5) at four different self‐selected speed levels slow, medium, fast and their maximum. Cycle duration, cycle rate, cycle length, and relative and absolute cycle phase duration of the different techniques at the different speed levels were analysed by means of a video analysis system. The cycle rate in all tested classical and freestyle techniques was found to increase significantly (p < .01) with speed from slow to maximum. Simultaneously, there was a significant decrease in the absolute phase durations of all the investigated skiing techniques. A minor, not significant, change in cycle length, and the significant increase in cycle rate with speed showed that the classical and freestyle cross‐country skiing styles are dependent, to a large extent, on an increase in cycle rate for speed adaptation. A striking finding was the constant relative phase duration with speed, which indicates a simplified neural control of the speed adaptation in both cross‐country skiing styles. For the practitioner, the knowledge about the importance of increasing cycle frequency rather than cycle length in the speed adaptation can be used to optimise a rapid increase in speed. The knowledge about the decrease in absolute phase duration, especially the thrust phase duration, points to the need for strength and technique training to enable force production at a high cycle rate and skiing speed. The knowledge that the relative phase duration stays constant with speed may be used to simplify the learning of the different cross‐country skiing techniques.     

The relative age effect among elite youth competitive swimmers

Abstract

The aim of this study was to analyse the relative age effect (RAE) in competitive swimming. The best 50 Portuguese swimmers (12- to 18-year-olds) for the main individual swimming pool events of both genders were considered. Analysis was conducted on 7813 swimming event participants, taking account of respective swimmer birth dates and the Fédération Internationale de Natation points gained. Differences in the distribution of birth dates by quarter year were determined using the Chi-square. A one-way analysis of variance ANOVA was used to test for differences measured in points between individuals by quarterly birth year intervals. A two-way analysis of variance ANOVA was also conducted to test the interaction between gender and seasonal birth date with regard to performance. The results show an inequitable distribution (p<0.01) of birth dates by quarter for almost all age groups and both genders. However, the distribution of birth dates by quarter for each considered swim event shows that RAE seems to exist only for 12-year-old females and 12- to 15-year-old males. Analysing mean swimming performance, post-hoc results (p<0.01) show no consistency in RAE. Higher performance occurs among older swimmers only in 100 m butterfly (female 1998, 1st≠2nd quarter, p=0.003). The results also show no interaction between gender and seasonal birth date (p<0.01). Findings of this study show that a higher number of swimmers, particular males, are born in the first two quarters of the year, although there is mostly no effect of seasonal birth date on performance differences within the top 50 swimmers.     

我国服务贸易比较优势指标的反思——河北省为例

国际服务贸易的比较优势指标之间存在一定矛盾,同时采用RCA指数和TC指数判定国际服务贸易竞争力水平时结论常常发生矛盾。若调整RCA指数的内涵,把服务贸易与服务业相联系,那么既能分清楚两个指数分析问题的角度又能增强整个指标体系的解释力。若把相对市场占有率、RCA指数和TC指数组成一个指标体系,那么可以综合分析服务贸易进出口总额相对比较,服务贸易与服务业的相对比较,以及净出口的相对比较,三者既有机结合又相互印证。     

论体育体制改革的双重阻力

当今的体育体制改革面临来自既得利益集团和改革阵痛期的双重叠加阻力.来自既得利益集团的阻力称之为相对阻力,因其掌握着体育政策制定的决策权和话语权,对体育体制改革产生强大阻力.来自改革阵痛期的阻力具有人人利益受损的特点,所以称之为绝对阻力,因绝大多数社会公众远离体育政策的决策过程,对体育体制改革产生的阻力有限.针对被永久剥夺利益的特殊利益集团只能以强大的压力迫使其接受改革,除此之外的相对阻力可以采用补偿或者赎买的方式加以解决;绝对阻力是一种无法补偿的阻力,只能选择改革成本与预期收益在合理比的适当时机推进体育体制改革.     

Examining relative age effects on performance achievement and participation rates in Masters athletes

Abstract

Although the relative age effect has been widely observed in youth sports (Musch & Grondin, 2001 Musch, J. and Grondin, S. 2001. Unequal competition as an impediment to personal development: A review of the relative age effect in sport. Developmental Review, 21: 147–167. [Crossref], [Web of Science ®] , [Google Scholar]), it is unclear whether it generalizes across the lifespan. The purpose of this study was to examine the relative age effect among a population of Masters athletes using archived data. Two successive studies examined the frequency of record-setting achievements (Study 1) and the frequency of participation entries (Study 2) at the US Masters track-and-field and swimming championships as a function of an individual's constituent year within any 5-year age category. Results of Study 1 indicated that the probability of setting a record increased if Masters athletes were in the first year, and decreased if they were in the third, fourth or fifth year, of an age category. Results of Study 2 indicated that the likelihood of participating in the National championships increased if Masters athletes were in the first or second year, and decreased if they were in the fourth or fifth year, of an age category. We highlight and discuss potential advantages afforded to Masters athletes who are relatively younger than their peers in the same 5-year age category.     

Towards a unified understanding of relative age effects

Abstract

When athletes are placed into annual age groups to organize and coordinate sport participation, certain (dis)advantages occur as a result of the subtle age differences within these groups. These differences, termed “relative age effects”, have been consistently related to youth and adult sport attainment. However, there has been a lack of consistency in the terminology used in this area of research. In this paper, we consider the operational terms used in relative age research, discuss appropriate applications of terminology, and suggest directions for future research. Importantly, we argue for a unified understanding of what “relative age” means, stressing the need for clarity in directing future advances in the field.     

Effect of Manual Guidance on Acquiring a New Bimanual Coordination Pattern

Purpose: This study explored the relationship between the caring climate, empathy, prosocial behaviors, and antisocial behaviors, like bullying, in physical education, plus investigated whether empathy mediated the possible relationships between caring and social behaviors for boys and girls. Method: Middle school physical education students (N = 528) completed measures assessing a caring climate, empathy, social behaviors, and bullying. Results: A partial mediation model was supported, χ²(94) = 206.82, p < .001, comparative fit index = .97, Tucker-Lewis index = .96, root mean square error of approximation = .05, standardized root mean squared residual = .04, which was also invariant across sexes. A perceived caring climate positively predicted prosocial behavior and cognitive empathy and negatively predicted antisocial behavior, like bullying. Cognitive empathy mediated the relationship between caring and prosocial behavior. Conclusions: Collective findings suggest that creating a caring climate is one tool that physical education teachers may use to promote positive behavior.     

概率法及相对运动法对链孢霉的连锁遗传作图分析

针对遗传学教材关于链孢霉的连锁遗传分析中的三个问题：（1）两对等位基因是否连锁;（2）是否位于着丝粒同侧;（3）着丝粒与nic重组率、nic与ade间的重组率、着丝粒与ade间的重组率三者间不存在等式关系.对于（1）、（2）两个问题分别采用概率法给予解答,对于（3）运用相对运动的观点给了三者各自的计算方法及三者间等式关系,即着丝粒与nic重组率＋nic与ade间重组率=着丝粒与ade间的重组率.     

无产阶级贫困化理论教学中现存问题辨析

由于一些人认为马克思的无产阶级贫困化理论已经过时,所以在现行教学中存在两个问题,一是只讲资本积累理论,不讲无产阶级贫困化理论.有些人主观上认为这样做好像是为了维护马克思主义,但事实上只讲资本积累理论,不讲作为资本积累源泉的无产阶级贫困化,是对马克思主义理论的割裂.二是讲无产阶级的贫困化理论,但把这一理论讲解为无产阶级绝对贫困化根本不存在了,只存在无产阶级相对贫困化.这种对马克思主义无产阶级贫困化理论的讲解,犯了马克思所批判的“空想社会主义”理论的错误.     

论魏玛德国的经济

经济问题是导致魏玛共和国衰亡的一个重要因素.魏玛共和国的经济发展可分为战后经济混乱时期、经济相对稳定时期和经济萧条时期三个阶段.最后由于未能解决经济问题而导致魏玛共和国垮台.