Reviewing the Variability-Overuse Injury Hypothesis: Does Movement Variability Relate to Landing Injuries?

Purpose: Overuse injuries are common in sport, but complete understanding of injury risk factors remains incomplete. Although biomechanical studies frequently examine musculoskeletal injury mechanisms, human movement variability studies aim to better understand neuromotor functioning, with proposed connections between overuse injury mechanisms and changes in motor variability. Method: In a narrative review, we discuss the variability-overuse injury hypothesis, which suggests repeated load application leads to mechanical tissue breakdown and subsequent injury when exceeding the rate of physiological adaptation. Due to the multidisciplinary nature of this hypothesis, we incorporate concepts from motor control, neurophysiology, biomechanics, as well as research design and data analysis. We therefore summarize multiple perspectives while proposing theoretical relationships between movement variability and lower extremity overuse injuries. Results: Experimental data are presented and summarized from published experiments examining interactions between experimental task demands and movement variability in the context of drop landing movements, along with comparisons to previous movement variability studies. Conclusion: We provide a conceptual framework for sports medicine researchers interested in predicting and preventing sports injuries. Under performance conditions with greater task demands, we predict reduced trial-to-trial movement variability that could increase the likelihood of overuse injuries.     

Kinematic analysis of hip and knee rotation and other contributors to ballet turnout

Turnout, or external rotation (ER) of the lower extremities, is essential in ballet. The purpose of this study was to utilise physical examination and a biomechanical method for obtaining functional kinematic data using hip and knee joint centres to identify the relative turnout contributions from hip rotation, femoral anteversion, knee rotation, tibial torsion, and other sources. Ten female dancers received a lower extremity alignment assessment, including passive hip rotation, femoral anteversion, tibial torsion, weightbearing foot alignment, and Beighton hypermobility score. Next, turnout was assessed using plantar pressure plots and three-dimensional motion analysis; participants performed turnout to ballet first position on both a plantar pressure mat and friction-reducing discs. A retro-reflective functional marker motion capture system mapped the lower extremities and hip and knee joint centres. Mean total turnout was 129±15.7° via plantar pressure plots and 135±17.8° via kinematics. Bilateral hip ER during turnout was 49±10.2° (36% of total turnout). Bilateral knee ER during turnout was 41±5.9° (32% of total turnout). Hip ER contribution to total turnout measured kinematically was less than expected compared to other studies, where hip ER was determined without functional kinematic data. Knee ER contributed substantially more turnout than expected or previously reported. This analysis method allows precise assessment of turnout contributors.     

普通高校体育专业开设拓展训练课程的实验研究

对两组实验对象进行2个阶段的拓展训练教学,通过对研究对象的测试和SCL—90量表调查发现:实验教学后对大学生的身体形态和身体机能影响不大,对身体素质有一定提高,对学生的心理素质有显著性提高,受到学生普遍的欢迎。     

将拓展训练融入大学体育课提高学生心理健康水平的可行性研究

通过实验法、问卷调查法等,把拓展训练融入大学体育课来提高学生心理健康水平进行了理论分析与实验研究。得出如下结论：1）拓展训练与体育课对大学生的心理健康提高均有重要作用。2）拓展训练有其自身的优势,但是传统体育课程也有其不可替代的作用,在教学中两者只有很好的结合,发挥各自的优势,才能更好地提高学生的综合素质。可以预见：用拓展训练的教学模式,补充和延伸体育教育的内容和功能,必将受到重视,那样可以更好地挖掘体育项目在德育、智育、美育等方面的潜在价值。建议高校根据本校实际情况有选择性地开设部分拓展训练课程,并逐步建立和完善符合本校教学实际情况的课程体系。     

肥胖症患者运动步态对下肢骨骼的承压性实验分析

目的:研究肥胖症患者运动步态对下肢骨骼承压性的影响。方法:将美国生产的Fastec Imaging高速摄像机置于人体行走的正侧面,受试者以正常行走的步速沿既定路线行走,随机拍摄,采用艾里尔配套的解析软件对拍摄的图像进行处理,通过比利时RSscan公司生产的压力分布测试系统Footscaninsole对受试者下肢骨骼承压型进行测试。结果:步宽肥胖组显著高于对照组,肥胖组的步长低于对照组,但无统计学意义。肥胖组相对步长显著高于对照组。双支撑时期,肥胖组显著大于对照组。单支撑时期肥胖组显著小于对照组。其余时间参数指标虽然在一定程度上有所变化,但无统计学意义。足跟着地时,肥胖组踝关节角度非常显著大于对照组。肥胖组髋关节角度显著大于对照组。在单支撑时相中,髋关节、膝关节、踝关节角度肥胖组与对照组相比有一定的改变,但无显著性意义。当足趾离地时,肥胖组在膝关节、踝关节处与对照组无显著性差异,在骸关节处的屈曲角度非常显著大于对照组。运动步态下肥胖组右下肢的腓骨、足骨平均峰力值显著高于对照组;肥胖组右下肢髌骨所受冲量显著高于对照组;肥胖组胫骨、足骨所受冲量非常显著大于对照组;其它区域肥胖组虽均高于对照组,但无统计学意义。结论:肥胖症患者运动步态下下肢骨骼所需承压性大于体重正常者。     

全面抗战初期张子斋的持久抗战思想论析

全面抗战初期,身居山国云南的张子斋,以笔为枪,在大量文章中抨击和揭露日本帝国主义者的侵华罪行,积极宣传抗战,并在中日对比中明确提出"持久抗战"和"抗战必胜"的思想,丰富了中国持久抗战理论,增强了云南人民积极抗战并取得最终胜利的信心。     

大班额情境下小学低年级语文有效教学策略研究

大班额教学已成为当前中国基础教育的普遍现象,在大班额教学背景下,教师应从实际出发,照顾到不同层次的学生。小学低年级语文教学是为学生打好基础的关键时期,教师要重视该阶段的教学方法和策略的选择,为学生的后续学习打好基础。     

对我国优秀男子三级跳远运动员在三跳中下肢摆动动作的分析

通过对部分中国优秀男子三级跳远运动员与部分外国优秀男子三级跳远运动员在三跳中起着地、离地瞬间两大腿间的夹角，支撑阶段摆动腿的摆动幅度和着地瞬间支撑腿大、小腿的角速度等反映下肢摆动动作积极程度的因素的分析对比，结合三级跳远的专项理论，得出中国优秀男子三级跳远运动员在三跳中下肢摆动动作与外国运动员的差距，并针对性地提出建议。     

实二次域Q(p～(1/2))(p≡3(mod4))类数的上界

设 p是适合 p≡ 3 (mod4)的奇素数 ,h,ε分别是实二次域 Q(p )的类数和基本单位 .本文运用初等方法证明了 :εh <(p +a +2 ) a+ 2 /4(a +2 ) !,其中 a =[(p +1 ) /2 ]     

斯特林制冷机制冷率和制冷系数的界限

研究了受热阻、热漏和回热损失影响的不可逆斯特林制冷机制冷率和制冷系数的最高和最低界限。为斯特林制冷机工作参数的选择提供了两条有限时间热力学新准则。