The influence of social identity on self-worth,commitment, and effort in school-based youth sport

???The current study examined the influence of social identity for individual perceptions of self-worth, commitment, and effort in school-based youth athletes. Using a prospective research design, 303 athletes (M_age = 14.89, SD = 1.77; 133 female) from 27 sport teams completed questionnaires at 2 time points (T1 – demographics, social identity; T2 – self-worth, commitment, effort) during an athletic season. Multilevel analyses indicated that at the individual level, the social identity dimension of in-group ties (IGT) predicted commitment (b = 0.12, P = .006) and perceived effort (b = 0.14, P = .008), whereas in-group affect (IGA) predicted commitment (b = 0.25, P = .001) and self-worth (b = 2.62, P = .006). At the team level, means for IGT predicted commitment (b = 0.31, P < .001) and self-worth (b = 4.76, P = .024). Overall, social identity accounted for variance at both levels, ranging from 4% (self-worth) to 15% (commitment). Identifying with a group to a greater extent was found to predict athlete perceptions of self-worth, commitment, and effort. More specifically, at the individual level, IGT predicted commitment and effort, and IGA predicted commitment and self-worth. At the team level, IGT predicted commitment and self-worth.     

Effects of movement velocity and maximal concentric and eccentric actions on the bilateral deficit

Department of Health, Physical Education, Recreation, and Dance at the University of Idaho. This study was performed to examine the effects of movement velocity and maximal concentric and eccentric actions on the bilateral deficit. Eighteen female participants performed maximal unilateral and bilateral knee extensions concentrically and eccentrically across six movement velocities (30, 60, 90, 120, 150, and 180 degrees/s). Repeated measures analyses of variance revealed significant differences (p < .025) between bilateral and summed unilateral contractions both concentrically and eccentrically at each velocity tested. Post hoc analyses revealed that the degree of bilateral deficit increased as movement velocity increased for concentric actions (e.g., 17-33% deficit, for 30 and 180 degrees/s, respectively), and an increasing trend was seen for eccentric actions (e.g., 18-25% deficit, for 30 and 180 degrees/s, respectively). These findings suggest that with increased velocity, a decreased or incomplete activation of fast twitch muscle fibers may have occurred in bilateral actions when compared to unilateral actions.     

诗人的故乡

这里的经济比较发达,人们都满足于生活的闲适和平和,多少年都没有太大的变化,坐在湖区的小酒馆中喝威士忌酒,你会以为自己回到了维多利亚时期的英国     

Effects of aerobic and cognitively-engaging physical activity on academic skills: A cluster randomized controlled trial

ABSTRACT

This cluster randomized controlled trial (trial-number #) compares effects of two school-based physical activity interventions (aerobic vs. cognitively-engaging) on reading, mathematics, and spelling achievement; and whether effects are influenced by volume of moderate-to-vigorous physical activity and baseline achievement. Twenty-two primary schools participated, where a third and fourth grade class were randomly assigned to the intervention or control group. Intervention groups were randomly assigned to a 14-week aerobic or cognitively-engaging intervention, receiving four physical education lessons a week. Control groups followed their regular physical education program. Academic achievement of 891 children (mean age 9.17 years, 49.4% boys) was assessed with standardized tests before and after the interventions. Post-Test academic achievement did not significantly differ between intervention groups and control group. A higher volume of moderate-to-vigorous physical activity resulted in better post-test mathematics achievement in both intervention groups, and post-test spelling achievement in the cognitively engaging intervention group. Compared to the control group, lower achievers in reading performed better in reading after the cognitively-engaging intervention. A combination of moderate-to-vigorous physical activity and cognitively-engaging exercises seems to have the most beneficial effects. Future intervention studies should take into account quantitative and qualitative aspects of physical activity, and children’s baseline academic achievement.     

世界杯女子佩剑决定性动作起动和时机距离值的准定量研究

为使佩剑研究可定量化,将技术类别划分为一单步和多单步对攻以及单纯进攻和单纯防守,通过录像解析数据对世界杯女子佩剑冠、亚、季军技术进行了定量和统计分析.结果显示,以身体重心水平速度为基准,参考录像表象分析,所确定决定性动作的起动时刻更客观有效可信,由此确定的时机距离较好地反映了运动员对进攻时机和进攻有机组合距离值的把握能力;双方的前脚间距是培养适宜时机距离感的重要指标,双方后脚间距离是诊断时机距离准确可靠的单选指标;对攻时,相对对手略微晚起动和缩小时机距离是女子佩剑优秀运动员的原则性特征技术.