Mathematical modelling as a tool to assessment of loads in volleyball player’s shoulder joint during spike     

Jacek Jurkojć  Robert Michnik  Krzysztof Czapla 《Journal of sports sciences》2017,35(12):1179-1186

This article deals with kinematic and kinetic conditions in volleyball attack and identifies loads in the shoulder joint. Joint angles and velocities of individual segments of upper limb were measured with the use of the motion capture system XSENS. Muscle forces and loads in skeletal system were calculated by means of mathematical model elaborated in AnyBody system. Spikes performed by players in the best and worst way were compared with each other. The relationships were found between reactions in shoulder joint and flexion/extension, abduction/adduction and rotation angles in the same joint and flexion/extension in the elbow joint. Reactions in shoulder joint varied from 591 N to 2001 N (in relation to body weight [BW] 83–328%).

The analysis proved that hand velocity at the moment of the ball hit (which varied between 6.8 and 13.3 m s^–1) influences on the value of reaction in joints, but positions of individual segments relative to each other are also crucial. It was also proved in objective way, that position of the upper limb during spike can be more or less harmful assuming that bigger reaction increases possibility of injury, what can be an indication for trainers and physiotherapists how to improve injury prevention.  相似文献   

Biomechanics of judo backward breakfall for different throwing techniques in novice judokas     

Sentaro Koshida  Takanori Ishii  Tadamitsu Matsuda  Toshihiko Hashimoto 《European Journal of Sport Science》2017,17(4):417-424

It is generally accepted that proper learning of the breakfall technique during early judo training is essential for attenuating the risk of judo-related head injury. Therefore, it is critical to understand the kinematics and head injury risks of breakfall motion to design a more safe and effective judo teaching paradigm that results in reduction of injury risk. We aimed to investigate the biomechanics of judo backward breakfalls by comparing osoto-gari and ouchi-gari in novice judokas. Twelve male novice judokas (age: 21.3 years, SD?=?0.6 years; height: 1.74?m, SD?=?0.04?m; body weight: 71.3, SD?=?6.4?kg; body mass index: 23.5, SD?=?2.3) volunteered to participate in this study. The kinematic data of the breakfall motion for both osoto-gari and ouchi-gari were collected using a three-dimensional motion analysis technique (200?Hz). We observed significant differences between the movement patterns for the two techniques, especially in the lower extremity movements. In addition, a significantly greater peak extension momentum (osoto-gari: 1.29, SD?=?0.23?kg?m^2?s^?1; ouchi-gari: 0.84, SD?=?0.29?kg?m^2?s^?1) and lower head position along the vertical axis (osoto-gari: 0.18, SD?=?0.05?m; ouchi-gari: 0.31, SD?=?0.08?m) with a large effect size were found in the breakfall for osoto-gari. Our results suggest that a different paradigm is needed for effectively teaching each breakfall technique that will enable us to substantially lower the risk of judo-related head injuries in novice judokas.  相似文献   

Could Slackline Training Complement the FIFA 11+ Programme Regarding Training of Neuromuscular Control?     

Tobias Jäger  Julian Kiefer  Inge Werner 《European Journal of Sport Science》2017,17(8):1021-1028

The current study compared changes in neuromuscular control between slackline training and the stabilization training elements of the FIFA 11+ programme. Twenty-five students in 2 groups performed a 12-unit training programme. The slackline training group (n?=?13) exclusively trained with a slackline. The stabilization training group (n?=?12) practised exercises as described in the second part of the FIFA 11+ programme. Improvements in balance were assessed using three tests for dynamic, quasi-static, and perturbed postural control: the star excursion balance test (SEBT), the closed-eye single-leg stance, and the MFT S3-Check. Both groups significantly improved the stability and sensorimotor index of the MFT S3-Check (p?<?.001), their range on the SEBT (p?<?.001), and the duration of closed-eye single-leg stance (p?<?.001). The group?×?training interaction was significant for the MFT S3-Check (stability index: p?=?.042; sensorimotor index: p?=?.004) and the SEBT (dominant leg: p?=?.003; averaged both legs: p?=?.016), with the slackline training group showing a larger training effect than the stabilization training group. The results of the present study suggest that slackline training offers similar – or better – improvements in neuromuscular control as the FIFA 11+ warm-up programme. If compliance with the FIFA 11+ programme is declining, then slacklining might offer an alternative approach to reach the training goals of improved sensorimotor control.  相似文献   

Increasing hip and knee flexion during a drop-jump task reduces tibiofemoral shear and compressive forces: implications for ACL injury prevention training     

Liang-Ching Tsai  Yi-An Ko  Kyle E. Hammond  John W. Xerogeanes  Gordon L. Warren  Christopher M. Powers 《Journal of sports sciences》2017,35(24):2405-2411

Although most ACL injury prevention programmes encourage greater hip and knee flexion during landing, it remains unknown how this technique influences tibiofemoral joint forces. We examined whether a landing strategy utilising greater hip and knee flexion decreases tibiofemoral anterior shear and compression. Twelve healthy women (25.9 ± 3.5 years) performed a drop-jump task before and after a training session (10–15 min) that emphasised greater hip and knee flexion. Peak tibiofemoral anterior shear and compressive forces were calculated using an electromyography (EMG)-driven knee model that incorporated joint kinematics, EMG and participant-specific muscle volumes and patella tendon orientation measured using magnetic resonance imaging (MRI). Participants demonstrated a decrease in peak anterior tibial shear forces (11.1 ± 3.3 vs. 9.6 ± 2.7 N · kg^?1; P = 0.008) and peak tibiofemoral compressive forces (68.4 ± 7.6 vs. 62.0 ± 5.5 N · kg^?1; P = 0.015) post-training. The decreased peak anterior tibial shear was accompanied by a decrease in the quadriceps anterior shear force, while the decreased peak compressive force was accompanied by decreased ground reaction force and hamstring forces. Our data provide justification for injury prevention programmes that encourage greater hip and knee flexion during landing to reduce tibiofemoral joint loading.  相似文献   

医院内肺部真菌感染的临床分析     

林荣  赵秀芳 《河北北方学院学报(医学版)》2005,22(2):59-61

目的:引起临床医师对医院内肺部真菌感染(PFIH)的高度重视.方法:对56例医院内肺部真菌感染的病例进行临床分析.结果:45例患者均患有慢性肺部疾病,其中以慢性阻塞性肺病、慢性肺原性心脏病导致的PFIH最多占68%.住院日的延长,广谱、多种抗生素的长时间应用,糖皮质激素和免疫抑制剂的使用,是PFIH常见的医源性因素.痰培养念珠菌属占91%,特别是白色念珠菌即占82%.结论:应尽可能减少或避免导致PFI  相似文献   

现浇混凝土裂缝缺陷的成因及防治和处理     

刘钟 《石家庄铁路职业技术学院学报》2007,6(2):68-71

分析混凝土裂缝缺陷产生的原因，研究得出裂缝的防治办法。  相似文献   

低重复率稿件中的学术不端行为检测与防范     

吴昔昔  贾建敏  吴健敏  王小同 《编辑学报》2016,28(3):266-269

重复率低却存在抄袭的稿件,其原因可能为单一的检测系统存在漏洞,新发表的论文上传数据库存在时间差,作者对稿件的有意识“修饰”,以及网络时代造假手段多样化.为此,文中提出以下措施:使用多种数据库进行文字检测,从查重报告中发现问题,建立有效的审稿专家数据库、网站教育和警示,充分利用网络资源,加快稿件处理进程,增强编辑的责任意识等,以利于更好地防范学术不端行为.  相似文献   

编辑侵犯作者修改权:原因与防范   总被引：1，自引：0，他引：1  

伯林 《安庆师范学院学报(社会科学版)》2002,21(2):108-110

编辑侵犯作者修改权是一个比较突出的行业侵权现象.导致的原因主要有:编辑法制观念淡薄;编辑编德素养不够;编辑学识水平跟不上;编辑修改权限界说不统一,著作权法不完善.应采取相应的措施,防范类似现象继续发生.  相似文献   

环境中氡及其子体的危害与防治     

何登良  刘家琴  王海滨  罗娅君 《绵阳师范学院学报》2007,26(8):55-60

氡是自然界中广泛存在的一种天然放射性气体,是人居环境中最直接的污染物,其危害是看不见、摸不着的,氡及其子体是铀、钍等放射性元素产物,是引发肺癌的重要致病因子,氡对人体的辐射伤害占人体所受到的全部环境辐射的55%以上,长期受到氡辐射,会导致肺癌、白血病、皮肤癌及其它呼吸道病变的产生。因此国内外科技界也越来越关注氡的辐射问题,为提高空气品质,保护人体免受辐射危害,本文重点介绍了氡的物理化学性质、环境中氡的来源及浓度水平、各种建筑材料中放射性核素的含量,讨论了通风对室内氡水平的影响,认为依靠住宅建筑和装修完成后的补救措施来防治室内氡危害的效能是有限的,防治室内氡危害的关键措施是从源头上减少氡的来源。  相似文献   

高校内部经济责任审计的特征与风险防范   总被引：2，自引：0，他引：2  

舒蓉雯 《浙江教育学院学报》2003,(4):56-59

高校内部经济责任审计具有审计对象双重性、审计内容广泛性、审计结果作用多元性、审计高风险性等特征。在分析高校内部经济责任审计风险原因的基础上，提出了一些质量控制和防范风险的措施。  相似文献