Can fast-twitch muscle fibres be selectively recruited during lengthening contractions? Review and applications to sport movements     

Gordon R. Chalmers 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(1):137-157

Literature examining the recruitment order of motor units during lengthening (eccentric) contractions was reviewed to determine if fast-twitch motor units can be active while lower threshold slow-twitch motor units are not active. Studies utilizing surface electromyogram (EMG) amplitude, single motor unit activity, spike amplitude–frequency analyses, EMG power spectrum, mechanomyographic, and phosphocreatine-to-creatine ratio (PCr/Cr) techniques were reviewed. Only single motor unit and PCr/Cr data were found to be suitable to address the goals of this review. Nine of ten single motor unit studies, examining joint movement velocities up to 225°/s and forces up to 53% of a maximum voluntary contraction, found that the size principle of motor unit recruitment applied during lengthening contractions. Deviation from the size principle was demonstrated by one study examining movements within a small range of low velocities and modest forces, although other studies examining similar low forces and lengthening velocities reported size-ordered recruitment. The PCr/Cr data demonstrated the activation of all fibre types in lengthening maximal contractions. Most evidence indicates that for lengthening contractions of a wide range of efforts and speeds, fast-twitch muscle fibres cannot be selectively recruited without activity of the slow-twitch fibres of the same muscle.  相似文献   

Gender differences in lower limb frontal plane kinematics during landing     

Gerwyn Hughes  James Watkins  Nick Owen 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(3):333-341

The aim of this study was to investigate gender differences in knee valgus angle and inter-knee and inter-ankle distances in university volleyball players when performing opposed block jump landings. Six female and six male university volleyball players performed three dynamic trials each for which they were instructed to jump up and block a volleyball suspended above a net set at the height of a standard volleyball net as it was spiked against them by an opposing player. Knee valgus/varus, inter-knee distance, and inter-ankle distance (absolute and relative to height) were determined during landing using three-dimensional motion analysis. Females displayed significantly greater maximum valgus angle and range of motion than males. This may increase the risk of ligament strain in females compared with males. Minimum absolute inter-knee distance was significantly smaller, and absolute and relative inter-knee displacement during landing significantly greater, in females than males. Both absolute and relative inter-ankle displacement during landing was significantly greater in males than females. These findings suggest that the gender difference in the valgus angle of the knee during two-footed landing is influenced by gender differences in the linear movement of the ankles as well as the knees. Coaches should therefore develop training programmes to focus on movement of both the knee and ankle joints in the frontal plane in order to reduce the knee valgus angle during landing, which in turn may reduce the risk of non-contact anterior cruciate ligament injury.  相似文献   

运动损伤康复与预防的功能锻炼新思路     

汪黎明  李丹阳  王安利 《体育成人教育学刊》2013,(6):72-77

从运动损伤的机制分析入手,重点讨论肌肉平衡、姿势与动作模式异常等问题与损伤之间的循环关系,并分析指出姿势、动作模式的关键因素,以及康复功能锻炼对于人体运动系统的作用与损伤康复的基本原理。继而提出了从姿势、动作和肌肉平衡评估入手的损伤康复功能锻炼流程,包括评估流程和细节要求,针对性的肌肉紧张和肌肉无力处理方法与流程、本体感觉训练和整合训练要点等。  相似文献   

机动车道路交通事故民事损害赔偿若干问题研究——以实际案例为研究载体     

张迅雷 《北京工业职业技术学院学报》2012,11(4):132-135

以案例为研究载体,以机动车交通事故民事损害赔偿归责原则为切入点,注重研究道路交通事故损害赔偿责任的适用范围。在研究过程中突出解决保险赔偿问题在解决道路交通事故民事赔偿问题中的核心作用,并完善道路交通事故社会救助基金制度,从而更公平合理地处理交通事故造成的损害后果。  相似文献   

试析损伤参与度在法医学鉴定中的应用     

成静 《安康学院学报》2012,24(4):51-52,58

在人身伤害案件中,参与度鉴定是量化分析致害行为与损害后果之间因果关系程度的基本方法,是确定致害行为人法律责任的关键。我国目前尚无统一的损伤参与度鉴定标准及操纵性强的量化工具,加之参与度操作难度大,存在应用不够广泛、重新鉴定案件较多等问题。用定量比例去判断外因与后果的关系,简便、准确、科学地分清责任和计算赔偿金额,是法医学鉴定发展的必然趋势。  相似文献   

伊川县高考体育生运动损伤的调查研究     

杨顺利 《甘肃高师学报》2012,17(2):53-55

运用文献资料法、问卷调查法、统计法、访谈法,以伊川县三所高中240名高考体育生为调查对象,根据其准备高考体育加试前参加运动训练时出现损伤的特点和规律,分析其运动损伤的产生的缘由,总结运动损伤的原因,并提出了有效的预防措施,旨在减少体育生在运动中的伤害事故,为伊川县以后的高考体育生体育训练荐言献策.  相似文献   

论死亡损害赔偿中的损益相抵原则     

巩寿兵 《廊坊师范学院学报》2012,(4):100-103

基于生命的无价性,在死亡损害赔偿中,损益相抵原则的适用总体上呈现出一种在严格限制适用前提下的零散的或者碎片化的适用状态。所以,要对其适用现状进行深入了解,就必须详细地考察它的具体适用规划,对赔偿权利人所获得的死亡赔偿金金额的确定和赔偿权利人所获得的利益的种类进行具体分析。  相似文献   

肋骨损伤院前首诊急救治疗对临床疗效的影响分析     

刘舒畅  喻风雷 《岳阳职业技术学院学报》2012,27(2):94-96

目的探讨肋骨损伤院前首诊急救治疗对临床疗效的影响。方法根据病史釆集过程中对院前首诊急救治疗的情况分为标准组47例,对照组21例,釆用双盲法覌察两组临床疗效相关指标。结果两组患者在受伤机制、伤情程度、死亡率等指标上均无显著性差异(p>0.05),在平均住院时间、康复率、重伤率等指标上差异有统计学意义(p>0.05)。结论肋骨损伤院前首诊急救治疗,可降低患者的伤残率和死亡率,提高患者的抢救成功率,给予患者有效、合理、及时的院前急救是患者生存的关键。  相似文献   

LacZDNA标记的腺病毒在高氧性肺损伤基因治疗中的转染和致炎作用     

王燕  AronB．Fisher  张灵恩 《新课程学习(社会综合)》2012,(2)

目的：LacZDNA标记的腺病毒在高氧性肺损伤基因治疗中的转染和致炎作用。方法：装载LacZDNA的腺病毒在小鼠高氧模型开始前2天经鼻腔送入体内X-lal染色和β一半乳糖酶活性测定用于确定LacZDNA在肺内转染的分布及其蛋白表达产物的活性;小鼠肺干,湿重比和支气管肺泡盥洗液（BALF）内的蛋白浓度的测定用于鉴定腺病毒在基因治疗过程中可能存在的致炎作用。结果：X-gal染色显示LacZDNA在高氧前及后均可广泛转染在肺各级支气管和肺泡上皮细胞,β一半乳糖酶活性的测定提示了LacZDNA可成功地翻译成其蛋白质表达产物并表现为高表达;同时,腺病毒的致炎作用在高氧吸入48h后示小鼠肺干,湿重比和BALF蛋白浓度均较其他对照组明显升高,但其升高的程度可在24h后迅速缓解上升趋势。结论：腺病毒为载体的基因治疗可有效地转染标记基因,同时,腺病毒虽在基因治疗的过程中有一定的致炎作用,但是暂时的,其仍是有效的DNA载体。  相似文献   

《民法典》施行背景下足球伤害法律适用的新发展     

赵毅 《上海体育学院学报》2022,(2):1-13

在《中华人民共和国民法典》（以下简称《民法典》）施行背景下,足球伤害法律适用出现了新发展,对足球治理带来新挑战和新影响。就足球伤害的侵权归责原则而言,过去广为适用的公平责任原则不再适用,这将极大地增强社会足球和校园足球活动参加者、组织者的信心。《民法典》第1176条第1款明确规定了文体活动自甘风险规则的构成要件,对于足球运动参加者明确足球伤害法律适用规则提出了新要求。在三阶层的体育伤害侵权构造下,足球伤害的法律适用将从构成要件该当性、违法性和有责性三个层次递次考量。其中,对于作为违法阻却要件的自甘风险规则认定和作为有责性组成部分的重大过失认定将成为《民法典》时代足球伤害法律适用的核心议题。  相似文献