Multivariate isokinetic asymmetry of the knee and shoulder in elite volleyball players

Abstract

Muscle strength asymmetries have been investigated in athletes under the assumption of their connection to functional discrepancies and injuries. In volleyball, which is a highly asymmetric sport, this assumption becomes a well established research hypothesis. Given the almost complete lack of scientific evidence on this hypothesis, the present study focused on the detailed multivariate quantification of muscle asymmetries in offensive volleyball players. Twenty-four elite athletes (age 24.71±4.44 years, weight 84.62±6.24, height 190.08±5.58) were tested for concentric isokinetic muscle strength (a) of the internal and external rotators of the shoulder and (b) of the quadriceps and hamstrings of the knee at 60^o/s. Significant multivariate results were found for absolute (Max-Min) asymmetry in the upper (Hotteling's T ²=8.801, F=7.447, P=0.001) and the lower limbs (Hotteling's T ²=16.382, F=13.862, P=0.000), for fluctuating asymmetry (Dominant-Non Dominant) in the upper limbs (Hotteling's T ²=5.584, F=4.296, P=0.013) and for directional asymmetry (Left-Right) in the lower limbs (Hotteling's T ²=3.593, F=3.041, P=0.036). It appears that the upper and lower limbs of offensive volleyball players present significant composite muscle strength asymmetries, which should be taken into consideration in training and rehabilitation.     

统一战线在毕节试验区的实践与同心思想

毕节试验区是党和政府为发展西部贫困地区所选取的一个典型个案。毕节试验区的发展离不开当地各族人民的共同努力,同时也离不开统一战线的积极支持。统一战线充分发挥自己的人才优势、智力优势和政治优势,以点带面,为促进毕节试验区的各项建设事业全面快速发展做出了巨大的成绩。统一战线在毕节试验区的实践是对中国共产党提出的同心思想的最好诠释。     

北狮运动员膝关节屈伸肌群等速向心收缩生物力学特性的研究

目的:通过对湖南师范大学9名北狮运动员双侧膝关节屈伸肌群进行等速测试,为揭示该项运动膝关节肌群收缩的生物力学特性提供实验依据。方法:采用BIODEX SYSTEM 3等速测试系统对湖南师范大学北狮运动员膝关节屈伸肌群进行等速测试,测试指标为峰力矩、相对峰力矩、屈伸肌峰力矩比、平均功率及做功疲劳度。结果:1)北狮运动员双侧膝关节屈伸肌峰力矩和相对峰力矩随测试速度的增加呈递减趋势;2)狮头狮尾屈伸肌群峰力矩比值和做功疲劳度无显著性差异;3)狮头狮尾左右膝关节同一肌群峰力矩无显著性差异。结论:舞狮运动员膝关节肌群峰力矩变化随测试速度的增加而减少,平均功率呈现随运动速度的增加而增加,到达一定速度后随速度的增加而减少的特征。     

利用离心向心训练法发展投掷运动员爆发力的实验研究

从肌肉不同收缩类型(离心收缩、向心收缩)的固有特性出发，在发展投掷运动员爆发力训练手段中，侧重安排了肌肉的离心收缩训练，经过9个月的训练实践，结果证明：这样的安排是可行的，有效的，运动员的各项素质指标及专项成绩均有显著性提高。     

“同心”品牌服务毕节试验区“升级版”路径探索

"同心"品牌作为统一战线服务科学发展的知名品牌,在助推毕节试验区改革发展过程中具有不可替代的作用。实施毕节试验区改革发展"升级版"战略,要进一步发挥"同心"品牌的重要作用。首先要明确"升级版"和"同心"品牌的内涵,找准"同心"品牌的发力点;不断推进同心工程建设;加大宣传力度,提升"同心"品牌认可度和美誉度;充分发挥毕节试验区专家顾问组的重要作用;发挥民主党派联系广泛的优势,借助民主党派中央、省委和各对口帮扶单位的智慧和力量,强化"同心"品牌的帮扶效应;扩大与工商联合作的区域,打造海外引资平台;筹建"同心学院",推广"同心"文化,彰显"同心"品牌价值。     

Developing a Framework and Agenda for Students' Voices in the School System across Europe: from diametric to concentric relational spaces for early school leaving prevention

There are significant lacunae in the otherwise highly progressive documents on early school leaving prevention from the European Commission and Council in 2011, as part of the EU2020 headline target of 10% early school leavers across the EU. These documents offer no explicit account or analysis of the voices of children and young people, nor vision of systemic accountability of schools to students’ needs. This article argues that key problems of early school leaving can be interpreted as system level blockages in communication, including blockage in communication of children's voices. It seeks to develop a conceptual framework for understanding relational systems by reinterpreting a particular dimension of the structuralist anthropology of Lévi-Strauss’ cross-cultural examination of systems of relation, namely, the interplay between diametric oppositional and concentric relational spaces. The theoretical framework proposed in this article will also seek to translate structural features of system change into structural indicators for system scrutiny and accountability. Identification of key structural indicators is to facilitate change beyond blocked, diametric school space and towards concentric relational spaces in the school system — based on diverse accounts of students’ voices and needs in specific European contexts, as part of a potential strategy at European level to prevent early school leaving. Emerging issues highlighted as an agenda for reform include authoritarian teaching, alternatives to suspension, splits in communication, emotional supports, teacher conflict resolution skills and substantive structures and processes for active student voices in school.     

解析高水平大学

从高水平大学的概念视角和实体视角阐释高水平大学的本质。基于概念的视角,高水平大学的本质特征表现为比较性、模糊性、精神性和建设性四个维度;基于实体的视角,高水平大学的本质特征分为精神层、制度层和技术层三个层次。高水平大学的概念特征和实体特征具有同一性。     

周素园“同心”思想及其启示

周素园作为贵州毕节地区的红色文化名人,一生的思想丰富深刻,其中“同心”思想是最为典型的表现,其内涵包括：思想上同心同德：主动学习马列,接受并支持共产党的正确主张;目标上同心同向：彰显爱国心,渴望民族独立,人民解放;行动上同心同行：坚持共产党的领导,走无产阶级革命道路。新时期应充分借鉴周素园“同心”思想,增强高校思想政治理论课教学效果。     

Electromyographic analysis of exercise resulting in symptoms of muscle damage

Surface electromyographic (EMG) signals were recorded from the hamstring muscles during six sets of submaximal isokinetic (2.6 rad s -1 ) eccentric (11 men, 9 women) or concentric (6 men, 4 women) contractions. The EMG per unit torque increased during eccentric (P < 0.01) but not during concentric exercise. Similarly, the median frequency increased during eccentric (P < 0.01) but not during concentric exercise. The EMG per unit torque was lower for submaximal eccentric than maximum isometric contractions (P < 0.001), and lower for submaximal concentric than maximum isometric contractions (P < 0.01). The EMG per unit torque was lower for eccentric than concentric contractions (P < 0.05). The median frequency was higher for submaximal eccentric than maximum isometric contractions (P < 0.001); it was similar, however, between submaximal concentric and maximum isometric contractions (P = 0.07). Eccentric exercise resulted in significant isometric strength loss (P < 0.01), pain (P < 0.01) and muscle tenderness (P < 0.05). The greatest strength loss was seen 1 day after eccentric exercise, while the most severe pain and muscle tenderness occurred 2 days after eccentric exercise. A lower EMG per unit torque is consistent with the selective recruitment of a small number of motor units during eccentric exercise. A higher median frequency during eccentric contractions may be explained by selective recruitment of fast-twitch motor units. The present results are consistent with the theory that muscle damage results from excessive stress on a small number of active fibres during eccentric contractions.