运动生理学肌肉力量的影响因素专家讲座.pptx

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,*,*,第四节、影响肌肉力量原因,（一）概述,人体在肌肉活动中所表现出来力量、速度、耐力、灵敏及柔韧等机能能力统称为身体素质,。,身体素质是人体各器官系统功效协同作用在骨骼肌工作中综合表现。,运动生理学肌肉力量的影响因素专家讲座,第1页,力量素质,是其它身体素质基础。,肌肉力量表现为：,绝对肌力,、相对肌力、肌肉暴发力、肌肉耐力等。,运动生理学肌肉力量的影响因素专家讲座,第2页,绝对肌力和肌肉横断面大小相关,横断面越大，绝对肌力越大,肌肉横断面大小取决于肌纤维数量和每条肌纤维粗细,绝对肌力只能反应整体力量，不能反应肌肉每条肌纤维性能,绝对肌力,运动生理学肌肉力量的影响因素专家讲座,第3页,相对肌力,肌肉单位横断面积,（/cm,2,）,所含有肌力。,但日常应用普通以绝对肌力,/,体重代替,与肌纤维类型及神经对肌肉调整能力相关,相对力量可更加好地评价运动员力量素质,运动生理学肌肉力量的影响因素专家讲座,第4页,相对与绝对暴发力训练,力量型项目如：举重、柔道等应增加肌肉体积增加肌肉块，追求绝对力量增加,短跑、跳跃、体操等以速度和灵敏为特点项目，应该保持轻体重同时增加肌肉相对力量主要靠神经募集更多肌纤维参加动作。,运动单位动员,运动生理学肌肉力量的影响因素专家讲座,第5页,（二）决定肌肉力量原因,Muscle,Tendon,Muscle fiber,Connective,tissue,1.肌肉横断面积,力量训练引发肌肉体积增加及肌肉力量增加，主要是因为肌纤维横截面积增加造成。,普通认为，训练使横断面积增加是因为训练促使肌原纤维合成增加所致，而对于肌纤维数目无显著影响。,运动生理学肌肉力量的影响因素专家讲座,第6页,2.肌纤维类型能量代谢为其关键原因,快肌纤维收缩力,慢肌纤维，供能速率快，单位时间内可完成更多机械功。,运动生理学肌肉力量的影响因素专家讲座,第7页,CK,运动生理学肌肉力量的影响因素专家讲座,第8页,Fast and Slow Muscle Fibers.,Fast muscle fibers,are adapted for rapid,powerful contractions.,Thick for strength but results in poor O,2,diffusion,Fatigue relatively quickly.,Slow muscle fibers,are adapted for sustained contraction.,Thin to aid diffusion of O,2,but weaker,Relative to fast fibers,slow fibers have.,Less SR,Ca,2+,remains in the cytosol longer.,More mitochondria,a better blood supply,and myoglobin.,运动生理学肌肉力量的影响因素专家讲座,第9页,3.肌纤维收缩时初长度,肌纤维处于一定长度时，横桥与细肌丝肌动蛋白结合数目最多，从而使肌纤维收缩力增加。,运动生理学肌肉力量的影响因素专家讲座,第10页,运动生理学肌肉力量的影响因素专家讲座,第11页,4.运动单位动员,（,Recruitment of motor units）,运动单位,（Motor Unit,MU）,一个,运动神经元和受其支配肌纤维所组成基本肌肉收缩单位称为，运动单位。,运动生理学肌肉力量的影响因素专家讲座,第12页,运动单位动员,生活经验：,熟睡时肌力？,早晨刚才清醒时肌力？,晨练后精神倍加振奋时肌力？,激烈运动后倍感疲劳时肌力,？,运动生理学肌肉力量的影响因素专家讲座,第13页,运动单位动员定义：,参加兴奋运动单位数目与兴奋频率结合，称为运动单位动员,（Motor Unit Involvement）,或运动单位,募集（,Motor Unit Recruitment）,运动生理学肌肉力量的影响因素专家讲座,第14页,A whole muscle is a group of muscle fibers,Muscle,Tendon,Muscle fiber,Connective,tissue,A tendon attaches a muscle to a bone.,A single action potential in a muscle fiber produces a twitch.,Gradations of whole muscle tension depend on the number of muscle fibers contracting,（1）一块肌肉由多条肌纤维组成，并受多个神经元控制，单纯一个神经元兴奋只表现出肌肉震颤，参加收缩神经元越多，力量越大，参加神经元数目多少取决于神经系统兴奋性。,运动生理学肌肉力量的影响因素专家讲座,第15页,Whole muscle tension depends on the size of the muscle,the extend of motor unit,recruitment,&the size of each motor unit.,The number of muscle fibers varies among different motor units.,Muscles performing refined,delicate movements have few muscle fibers per motor unit.,Muscles performing coarse,controlled movements have a large number of fibers per motor unit.,（2）,不一样神经元，其所支配肌纤维数目存在差异，所以兴奋时表现出收缩力量不一样。,运动生理学肌肉力量的影响因素专家讲座,第16页,（3）,一个运动单位中肌纤维数目越少越灵活；数目越多产生力量越大。,运动生理学肌肉力量的影响因素专家讲座,第17页,所以，运动单位募集包含两方面：,运动单位数目,和,运动单位种类,运动生理学肌肉力量的影响因素专家讲座,第18页,A motor unit is one motor neuron and the muscle fibers it innervates.,Each motor neuron controls several to thousands of muscle fibers,When a motor neuron fires,every muscle fiber controlled by it contracts,The asynchronous recruitment of motor units delays or prevents muscle fatigue.,（4）当某一个神经元兴奋时，其所支配全部肌纤维都收缩。但肌肉收缩时，并不是全部神经元支配全部肌纤维都同时参加。,运动生理学肌肉力量的影响因素专家讲座,第19页,A A,B B,连续最大力量收缩,连续50%最大力量收缩,100%,MUI,MUI,力量,力量,100%,50%,100%,100%,运动生理学肌肉力量的影响因素专家讲座,第20页,5.神经系统机能状态,(nerve system activity),神经系统兴奋性越高，募集运动单位越多；发放刺激频率越高，强直收缩力量越大,即使运动神经中枢处于最大兴奋状态，也不能同时调动全部肌纤维参加收缩。,有训练者可动员90%，无训练者可动员60%,运动生理学肌肉力量的影响因素专家讲座,第21页,Muscle tension also depends on the frequency of stimulation,A muscle twitch(contraction)lasts longer than the action potential that initiates it.,Thus a second action potential can occur before the muscle fiber relaxes,Repetitive stimulation of a muscle increases its tension by twitch summation.,If a muscle fiber is stimulated very rapidly,it cannot relax between stimuli.,The twitches merge into a smooth,sustained,maximal contraction called tetanus.,Latent period,Contraction,time,Relaxation,time,Muscle,twitch,Contractile,response,Action,potential,Stimulation,运动生理学肌肉力量的影响因素专家讲座,第22页,Figure 8.17Page 271,Contractile,activity,Action,potentials,Single,twitch,Twitch,summation,Tetanus,Stimulation,ceases or,fatigue,begins,Action potentials separated by time:,Muscle fibers relax:,Weak contraction,Action potentials in close sequence:,Muscle fibers relax less:,Stronger contraction,Action potentials in close sequence:,Muscles dont relax:,Creates maximal sustained contraction,Single,twitch,运动生理学肌肉力量的影响因素专家讲座,第23页,6.年纪与性别原因,进入青春期后男性肌力开始显著高于女性；20-30岁肌力最大，以后增龄性下降。,7.体重原因,运动生理学肌肉力量的影响因素专家讲座,第24页,These are two types of fatigue.,Muscle fatigue occurs when an exercising muscle can no longer respond to the same degree of stimulation with the same degree of contractile activity.,（外周疲劳）,Factors for this include an increase in inorganic phosphate,accumulation of lactic acid,and the depletion of energy reserves.,（电解质紊乱、代谢产物堆积、能量贮备受限）,Increased oxygen consumption is needed to recover from exercise(paying off an oxygen debt).,（缺氧）,Central fatigue occurs when the CNS can no longer activate motor neurons supplying working muscles.,（中枢疲劳）,It is often psychological and is related to biochemical changes at the synapses in the brain.,运动生理学肌肉力量的影响因素专家讲座,第25页,Muscle atrophy if not used!,Skeletal muscles atrophy when not used.,disuse atrophy,denervation atrophy,Skeletal muscles have a capacity for limited repair.,Can replace limited numbers of damaged muscle fibers,Large scale damage results in the replacement of damaged muscle fibers with non contractile connective tissue,运动生理学肌肉力量的影响因素专家讲座,第26页,