Bilateral deficit in power production during multi-joint leg extensions

Abstract

The purpose of this study was to determine the presence of the bilateral deficit both as a function of overall and individual joint power. Most studies addressing the deficit have assessed force; however, in most sporting events maximal power is more important than maximal force production. To address this, in the current study we assessed the bilateral deficit for multi-joint movements as measured by overall lower extremity and individual joint power. We assessed power production using an isokinetic machine permitting both unilateral and bilateral leg extensions. Several significant effects and interactions between the contraction type (unilateral, bilateral, alternating unilateral), side of the body, lower extremity joint, and percentage of a 1-RM load were revealed. All interactions were between the lower extremity joints (hip, knee, ankle) and involved the contraction protocol (P=0.001), the percentage of 1-RM load (P=0.0002), and the side of the body (P=0.0003). Taken together, the results indicate that the bilateral deficit is manifested using a measure of power, but more importantly, the deficit has differential implications based on the overall resistance, and various joints involved in the movement. In conclusion, a reduction in power generation was evidenced for both simultaneous contractions of the leg extensors as well as reciprocal contractions. With reduced contributions from the knee joint during bilateral and reciprocal contractions, combined with past research demonstrating differential activation of mono-articular knee joint muscles, evidence for reduced contributions from the peripheral nervous system are suggested based on the results of this study.     

短跑运动员专项力量训练的新思路

如何设计和选择专项力量训练手段,取决于教练对专项技术和力量本质特征的正确认识．现代短跑运动员技术的本质特征应视以髋为轴的高速摆动一平动运动．短跑专项力量训练是当代力量训练的核心,发展短跑专项力量不仅应采用负重的专项练习,而且更重要的是改进杠铃训练使其在练习形式、负荷和力度尽可能接近专项．     

太极拳运动中的足底压力分布研究

该研究对16名优秀太极拳练习者的5个典型太极动作的脚底9个区域的压力分布数据进行了采集和分析,结果表明:在太极拳运动中,脚底第1跖骨头和第1脚趾的压力载荷显著大于其它部位(P＜0.05);在太极拳的向前、向后和左右脚步动作中,足底压力中心的内外侧方向上的位移显著大于正常步行(P＜0.05);在太极拳的向前脚步移动中,足底压力中心的前后侧方向上的位移显著大于正常步行(P＜0.05).该研究认为太极拳运动的足底压力分布特征可能是造成太极拳运动能够提高平衡和控制肌肉力量的重要因素之一.     

对不同训练水平短跑运动员相关肌群变化规律的研究

通过对不同训练水平短跑运动员相关肌群变化规律的探索,揭示出不同训练水平短跑运动员肌肉工作特点及内在联系,明确各肌群力量素质的合理比例,为今后短跑运动教学与训练提供参考和咨询.     

A functional model of the digital extensor mechanism: Demonstrating biomechanics with hair bands

The action of muscles about joints can be explained through analysis of their spatial relationship. A functional model of these relationships can be valuable in learning and understanding the muscular action about a joint. A model can be particularly helpful when examining complex actions across multiple joints such as in the digital extensor mechanism of the hand. A functional model using two hair bands representing the components of the digital extensor mechanism is described. Through superimposition of the model over one's digit, the combined actions of metacarpophalangeal joint flexion and interphalangeal joint extension are clearly demonstrated. The model provides a conceptual demonstration to enhance understanding of this unique combination of muscle actions about multiple joints. Anat Sci Educ, 2010. © 2010 American Association of Anatomists.     

浅谈腰背肌筋膜炎的防治

腰背肌筋膜炎是运动中最常见的一种慢性损伤,影响到体育锻炼者和运动员的身体健康,对体育锻炼和运动训练造成不利的影响．了解病因,通过相应的临床表现（隐隐疼痛、酸、麻、胀）来诊,治疗（按摩、体疗等）及采取预防措施是非常有意义的．     

不同处理因素对离体兔小肠平滑肌运动的影响

采用离体器官实验法,将家兔小肠分段,置于恒温通气麦氏浴皿培养液中,分别加入不同处理因素,以观察它们对小肠平滑肌运动的影响.试验结果表明:①平滑肌具有自动节律性、较大的展长性、紧张性、但节律性较差等生理特性.机械刺激可明显影响平滑肌的运动,2±0.5 s内收缩张力与正常水平相比差异极显著(P＜0.001).温度改变、酸碱变化均抑制平滑肌运动.能引起平滑肌兴奋的药物有乙酰胆碱(Ach)、新斯的明(Neo)等,使平滑肌收缩活动受抑制的药物有阿托品(Atr)、肾上腺素(Adr)等.②不同肠段对各种因素的敏感性存在差异.一般十二指肠最为敏感,空肠次之,回肠最差.     

生命科学与体育

生命科学的发展一日千里，人类基因组计划、生物芯片和分子克隆等技术犹如雨后春笋般呈现在人们面前，随之而兴起的生物信息学像一颗璀璨的明珠为生命科学揭开生命奥妙添光彩。作为更高、更快、更强的源泉，生命科学乃是体育的左膀右臂。在日益细化具体的学科分工和高度综合抽象的体育科学研究中，诸如运动中肌肉基因表达、应用生物芯片技术评价运动员身体机能等的价值越来越被人们所接受。     

离心运动对细胞外基质蛋白含量及膜完整性的影响

以雄性Wistar大鼠为研究对象,进行"一次性大强度离心运动",一次性离心运动实验为-16°下坡跑台跑,定量大负荷间歇性运动,跑速为26.8 m/min,运动5 min×10组,组间歇1 min。离心运动后不同时段取大鼠后肢腓肠肌外侧头进行分析大强度离心运动后大鼠骨骼肌细胞骨架蛋白含量的变化特点;与延迟性骨骼肌损伤时血清酶升高的关系;探讨细胞骨架蛋白在骨骼肌纤维中存在的特点和作用。     

简化24式太极拳对山西省高校大学生核心力量影响的研究--以太原学院2014级新生为例

24式简化太极拳能够显著提高男子的平板支撑、侧卧撑、站位前抛实心球、站位后抛实心球这几个指标,差异具有显著性;简化24式简化太极拳能够显著提高平板支撑、侧卧撑、站位后抛实心球、一分钟仰卧起坐这几个指标,差异具有显著性;24式简化太极拳能够提高大学生的核心力量,男女实验结果基本一致,没有太大差异性。