The relationship between bowling action classification and three-dimensional lower trunk motion in fast bowlers in cricket

Lower back injuries, specifically lumbar stress fractures, account for the most lost playing time in professional cricket. The aims of this study were to quantify the proportion of lower trunk motion used during the delivery stride of fast bowling and to examine the relationship between the current fast bowling action classification system and potentially injurious kinematics of the lower trunk. Three-dimensional kinematic data were collected from 50 male professional fast bowlers during a standing active range of motion trial and three fast bowling trials. A high percentage of the fast bowlers used a mixed bowling action attributable to having shoulder counter-rotation greater than 30 degrees. The greatest proportion of lower trunk extension (26%), contralateral side-flexion (129%), and ipsilateral rotation (79%) was used during the front foot contact phase of the fast bowling delivery stride. There was no significant difference in the proportions of available lower trunk extension, contralateral side-flexion, and ipsilateral rotation range of motion used during fast bowling by mixed and non-mixed action bowlers. Motion of the lower trunk, particularly side-flexion, during front foot contact, in addition to variables previously known to be related to back injury (e.g. shoulder counter-rotation), should be examined in future cross-sectional and prospective studies examining the fast bowling action and low back injury.     

Practical precooling: effect on cycling time trial performance in warm conditions

The purpose of this study was to compare the effects of two practical precooling techniques (skin cooling vs. skin + core cooling) on cycling time trial performance in warm conditions. Six trained cyclists completed one maximal graded exercise test (VO2(peak) 71.4 +/- 3.2 ml x kg(-1) x min(-1)) and four approximately 40 min laboratory cycling time trials in a heat chamber (34.3 degrees C +/- 1.1 degrees C; 41.2% +/- 3.0% rh) using a fixed-power/variable-power format. Cyclists prepared for the time trial using three techniques administered in a randomised order prior to the warm-up: (1) no cooling (control), (2) cooling jacket for 40 min (jacket) or (3) 30-min water immersion followed by a cooling jacket application for 40 min (combined). Rectal temperature prior to the time trial was 37.8 degrees C +/- 0.1 degrees C in control, similar in jacket (37.8 degrees C +/- 0.3 degrees C) and lower in combined (37.1 degrees C +/- 0.2 degrees C, P < 0.01). Compared with the control trial, time trial performance was not different for jacket precooling (-16 +/- 36 s, -0.7%; P = 0.35) but was faster for combined precooling (-42 +/- 25 s, - .8%; P = 0.009). In conclusion, a practical combined precooling strategy that involves immersion in cool water followed by the use of a cooling jacket can produce decrease in rectal temperature that persist throughout a warm-up and improve laboratory cycling time trial performance in warm conditions.     

当代大学生合作竞争精神及培养策略研究

本文分析了当代大学生具备合作竞争精神的意义,阐述合作与精神的内涵和具体内容,从教化熏陶、实践锤炼、环境打造等层面提出培养当代大学生合作竞争精神的具体措施。     

穿越夏天

<正>我无意怀旧,只想在这个时候去暖风的野外,赴夏天的约请。对于夏天,我真正读懂是在年近不惑之后。其实,凡是拜读过它的人都是知道的,它的任何一块土地、一座山峰、一条河流,都是血肉丰富、情感逼人的生命。民俗、文化、历史像野草一样在其中繁衍、延续,形成史诗。灵性的绿一团一团挤满山冈,灵性的白云浮在薄雾的峡谷,水的流动更加激越,远近高低的绿,是不可抗     

中西医结合防治胆石病基础研究进展

该文介绍了胆石病中西医结合防治基础研究的概况,同时介绍所取得的部分研究成果,阐述中西医结合防治胆石病的优势,并提出今后的研究思路及展望.     

试论我国发展虚拟制造技术的战略

虚拟制造技术是近年出现的一种先进制造技术，是一种最新的制造模式。本文从虚拟制造技术对制造业的作用的角度进行分析，提出了我国应从政府管理、企业、科研三个层面上发展虚拟制造技术战略的建议。     

蜡烛燃烧的综合实验探究

1　设计思想为了让学生更好的理解燃烧的有关知识 ,笔者结合全日制义务教育《科学 (7 9年级 )课程标准解读》(湖北教育出版社 )中“哪一支蜡烛先熄灭”的案例 ,设计了一组探究式实验。在本教学中 ,学生实验前应先预测可能的结果 ,既促使学生有意识、有目的的进行观察实验 ,并以此引发认知冲突 ,增强学生学习兴趣 ;实验后则重视实验结果的讨论与交流 ,有助于学生对知识的建构 ;评价试题则贴近生活 ,有利于学生将生活中所遇到的问题与所学科学知识进行有效的联结 ,使学生能应用、巩固、深化和扩展所学知识 ,提高科学学习兴趣。采用开放式试题…