运动性疲劳对跳深动作结构影响的生物力学分析

使用三维测力平台、Panasonic摄像机和MONARK 834E型功率自行车对20名男学生疲劳前后跳深动作进行测试,结果表明运动性疲劳引起跳深动作结构发生了显著性的变化,表现为重心速度的下降、腾起距离减少,以及与地接触时间显著性增加等特点;膝关节功能不断下降,膝关节角度变化范围明显增大,膝关节峰值功率显著性降低,最大横向和纵向的冲击力明显增大,垂直蹬伸力显著性降低.这些生物力学参数的改变,不但大幅降低了跳深训练的效果,同时增大了关节和肌肉损伤的风险.     

自由式滑雪空中技巧国家队运动员膝关节屈伸肌群肌肉力量特征

目的：为了观察我国自由式滑雪空中技巧队男女运动员下肢膝关节屈伸肌群力量特点,发现目前下肢力量训练中存在的问题,以便为力量训练提供参考依据。方法：使用美国BIODEX公司生产的biodex system4等动测试系统对自由式滑雪空中技巧队男女运动员（男5名,女6名）的下肢膝关节屈伸肌群进行向心收缩的等动测试,测试速度分别为60°/s和180°/s。结果：男女运动员伸肌群的相对峰值力矩和相对平均功率都要显著高于屈肌群（P<0.01）。相对峰值力矩随着测试速度的增加而显著减小（P<0.01）,相对平均功率随测试速度的增加而显著增加（P<0.01）。男女运动员下肢屈伸肌比平均在50%～65%之间,并且随着测试速度的增加屈伸肌比显著增加（P<0.05）。在同一速度下,男女运动员伸肌峰值力矩出现的角度要显著大于屈肌（P<0.01）,但是在不同速度下,男女运动员伸肌峰值力矩出现的角度表现出不同的变化。随着测试速度的增加,屈伸肌群峰值力矩出现的时间显著变短（P<0.01）,并且同一速度下,屈肌群峰值力矩出现的时间要短于伸肌群（P<0.05）。左右腿膝关节屈伸肌群相对峰值力矩、相对平均功率、屈伸肌比等指标没有差异（P>0.05）。结论：了解到目前我国自由式滑雪空中技巧队男女运动员下肢肌肉的力量特点,其中男女运动员下肢膝关节屈伸肌比（H/Q）较低,应该注重发展股后肌群的力量,以提升屈伸肌比值。左右腿肌肉力量发展比较均衡。     

助跑速度和性别对45度变向动作中下肢生物力学负荷的影响

目的:探究不同助跑速度下45°变向动作中男、女运动员下肢生物力学参数的变化情况。方法:运用三维红外高速摄像机和测力台对26名篮球运动员在不同助跑速度下45°变向动作中下肢生物力学运动学和动力学信号进行采集。运用Visual-3D分析软件对采集的信号进行处理并计算相关生物力学参数。结果:男、女运动员在快速助跑下足与地面接触时刻的膝关节外展角显著大于低速助跑(p<0.05)。快速助跑下男子运动员的最大膝关节外展角显著增加(p<0.05)。助跑速度显著影响男、女运动员的垂直地面反作用力、膝关节屈力矩和外展力矩参数(p<0.05)。女子运动员在膝关节屈角和最大膝关节外展角参数方面与男子运动员存在显著性差异(p<0.05)。快速助跑时女子运动员的垂直地面反作用力和膝关节屈力矩峰值均显著高于男子运动员(p<0.05)。中速助跑时,女子运动员的垂直地面反作用力峰值参数显著大于男子运动员(p<0.05)。结论:不同助跑速度对45°变向动作中男、女运动员部分下肢生物力学参数具有显著性影响。另外,同一助跑速度下部分下肢生物力学负荷参数也存在明显的性别差异性。     

佩戴膝关节护具对羽毛球运动员蹬跨步动作时髌股关节力学特征的影响

目的 探究佩戴2种膝关节护具对羽毛球运动员完成蹬跨步动作时髌股关节载荷的影响。方法 选取12名羽毛球高水平运动员佩戴无护具、佩戴髌骨带和佩戴护膝模拟,正手蹬跨步、正手被动蹬跨步动作,使用4块Kistler三维测力台、8台Qualisys红外高速摄像头同步采集受试者右侧下肢动力学与运动学数据,以对比佩戴膝关节护具前后跨步足落地阶段股髌关节力、关节应力、关节力矩和关节角度等参数。结果 与无膝关节护具相比,佩戴护膝能够显著减少正手蹬跨步、正手被动蹬跨步动作落地阶段的膝关节峰值屈曲角度（p<0.05）、显著减少膝关节峰值伸膝力矩（p<0.05）、显著减少髌股关节峰值力（p<0.05）、显著减少髌股关节峰值应力（p<0.05）。结论羽毛球运动员佩戴护膝完成蹬跨步动作时,均有较低的股髌关节峰值应力、股髌关节峰值力及股四头肌峰值力,同时发现佩戴护膝可以缓冲膝关节压力,对髌骨以及膝关节韧带等组织起到保护作用。鉴于此,运动员佩戴护膝能够减少膝关节疼痛、提高膝关节稳定性、降低运动损伤风险,以预防股髌关节疼痛综合症。     

跆拳道运动员前横踢动作优势侧和非优势侧的生物力学偏侧性研究

目的：探索跆拳道运动员前横踢动作下肢优势侧和非优势侧的运动生物力学特征差异性。方法：采用Vicon三维运动捕捉系统、Kistler三维测力台和Deado电子护具计分系统,采集13名跆拳道运动员前横踢动作下有效得分时髋、膝、踝关节的运动学和动力学数据,使用Visual3D软件对采集数据进行逆向运动学和动力学计算,并对结果采用配对样本T检验的方法进行差异性分析。结果：(1)进攻腿：髋关节屈曲力矩峰值、膝关节伸展力矩峰值优势侧大于非优势侧(p<0.05),膝关节屈曲最大角度优势侧大于非优势侧(p<0.01),髋关节伸展力矩峰值、外展最大角度非优势侧大于优势侧(p<0.01)。(2)支撑腿：髋关节屈曲幅度、屈曲功率峰值、外展功率峰值优势侧大于非优势侧(p<0.05),髋关节外展力矩峰值、膝关节伸展力矩峰值优势侧大于非优势侧(p<0.01),髋关节伸展角速度峰值、踝关节跖屈力矩峰值非优势侧大于优势侧(p<0.05),髋关节外展角速度峰值、膝关节屈曲力矩峰值、踝关节旋外角速度峰值非优势侧大于优势侧(p<0.01)。(3)进攻腿击打力度值及进攻腿和支撑腿垂直...     

青少年男子短跑运动员膝关节等速肌力特征研究

目的：通过对36名二级青少年男子短跑运动员双侧膝关节进行等速测试，探析青少年短跑运动员膝关节向心屈伸肌群的生物力学特性．为运动训练、科学选材及临床康复等提供理论依据。方法：利用Kinitech等速康复肌力测试系统对青少年男子短跑运动员膝关节屈伸肌群进行等速测试。结果：青少年男子短跑运动员双侧膝关节屈伸峰力矩随测试速度的增加呈递减趋势，且膝伸肌大于膝屈肌（P〈0．05），峰力矩屈伸比（V／E）随给定测试速度的增加呈递增趋势；最大功率随测试速度的增大而增加，同一测试速度下屈、伸肌群最大功率无明显差异，左、右侧相比也无显著性差异（600／s伸肌除外）；屈伸肌群达峰力矩的角度（APT）表现为伸肌角度明显低于屈肌角度，随速度增加左右两侧膝关节达峰力矩的角度无显著差异：双侧膝关节屈伸肌群达峰力矩的时间（TPT）随测试速度的增加而减小，同一测试速度下伸肌达峰力矩的时间大于屈肌；右侧膝关节屈肌相对峰力矩（PT／BM）与下肢形态学指标表现出不同程度的正相关。结论：青少年男子短跑运动员膝关节峰力矩变化规律与成年人相一致，但左右侧膝关节屈伸肌群做功能力发展不平衡，屈伸肌群运动达峰力矩角度、达峰力矩的时间存在显著差异。     

中国优秀男子短跑运动员途中跑垂直缓冲时段运动学参数的灰色关联度分析

通过对男子短跑运动员100m途中跑垂直缓冲时段运动学参数的灰色关联度分析，得出以下结论：下肢的关节点的夹角及上臂摆幅与跑速高度相关，各环节角度变化将影响短跑运动员跑进时的前蹬阻力及后蹬腿的蹬地方向，进而影响后蹬腿对地做功的有效功率。由此可见，增加短跑运动员途中跑垂直缓冲时段髋关节、膝关节及上臂前摆幅将有助于提高短跑的跑速。     

青少年男子篮球运动员膝关节等速肌力特征研究

通过对36名二级青少年男子篮球运动员双侧膝关节进行等速测试,探析青少年篮球运动员膝关节向心屈伸肌群的生物力学特性,为运动训练、科学选材及临床康复等提供理论依据.方法:利用 Kinitech等速康复肌力测试系统,对青少年男子篮球运动员膝关节屈伸肌群进行等速测试.结果表明:青少年男子篮球运动员双侧膝关节屈伸峰力矩随测试速度的增加呈递减趋势,且膝伸肌大于膝屈肌(P<0.05),峰力矩屈伸比(F/E)随给定测试速度的增加呈递增趋势;最大功率随测试速度的增大而增加,同一测试速度下屈、伸肌群最大功率无明显差异,左、右侧相比也无显著性差异(60°/s伸肌除外);屈伸肌群达峰力矩的角度(APT)表现为伸肌角度明显低于屈肌角度,随速度增加左右两侧膝关节达峰力矩的角度无显著差异;双侧膝关节屈伸肌群达峰力矩的时间(TPT)随测试速度的增加而减小,同一测试速度下伸肌达峰力矩的时间大于屈肌;右侧膝关节屈肌相对峰力矩(PT/BM)与下肢形态学指标表现出不同程度的正相关.本研究结论,青少年男子篮球运动员膝关节峰力矩变化规律与成年人相一致,但左右侧膝关节屈伸肌群做功能力发展不平衡,屈伸肌群运动达峰力矩角度、达峰力矩的时间存在显著差异.     

“屈蹬式”短跑技术的生物力学探究

“屈蹬式”短跑后蹬技术能够改变“后蹬型”技术的不足.“屈蹬式”后蹬结束时,膝关节仍保持较小的角度(150°～155°)这样就保证了屈膝肌较大的肌拉力角和拉力矩.另外小腿前倾用、后蹬角小,利于增大水平分力,减少重心波动差.因此在“屈蹬式”途中跑的后蹬阶段,后蹬腿产生后蹬力的生物力学特点是由大到小.对人体运动的作用,首先是使人体作向前上方加速运动;随后是使人体作垂直方向惯性运动、作水平方向加速运动.     

不同极简指数跑鞋对髌股关节受力特征的影响

聚焦跑步时髌股关节生物力学特征,探究穿着不同极简指数(MI)跑鞋对髌股关节接触力、应力等的即刻影响。选取15名习惯后跟着地的健康男性跑者,分别穿着两种MI跑鞋(MI 86%极简跑鞋和MI 26%缓冲跑鞋),使用Vicon红外运动捕捉系统、Kistler三维测力台同步采集3.33 m/s(速度变化范围±5%)跑速下的膝、踝关节运动学和地面反作用力,通过逆向动力学等计算股四头肌肌力、髌股关节接触力、髌股关节接触面积以及髌股关节接触应力。结果显示:两种跑鞋条件下的冲击力峰值和蹬地力峰值均无明显差异。与缓冲跑鞋相比,穿着极简跑鞋跑步时,膝关节最大屈曲角度显著降低(P<0.01);髌股关节接触面积显著减小(P<0.01);膝关节伸肌峰值力矩显著下降(P<0.01);髌股关节接触力和应力峰值均显著减小(P<0.05)。研究表明,相比缓冲跑鞋,穿着极简跑鞋在未影响触地后冲击力峰值的同时,通过降低伸膝力矩大幅度减少髌股关节接触力(下降17.02%)、降低髌股关节接触应力,从而有效改善支撑期髌股关节负荷,为进一步减小髌股关节疼痛综合征风险提供可能。     

Tennis forehand kinematics change as post-impact ball speed is altered

Peak joint angles and joint angular velocities were evaluated for varying speed forehands in an attempt to better understand what kinematic variables are most closely related to increases in post-impact ball velocity above 50% of maximal effort. High-speed video was used to measure three-dimensional motion for 12 highly skilled tennis players who performed forehands at three different post-impact ball speeds: fast (42.7 +/- 3.8 m/s), medium (32.1 +/- 2.9 m/s), and slow (21.4 +/- 2.0 m/s). Several dominant-side peak joint angles (prior to ball impact) increased as post-impact ball speed increased from slow to fast: wrist extension (16%), trunk rotation (28%), hip flexion (38%), knee flexion (27%), and dorsiflexion (5%). Between the aforementioned peak joint angles and ball impact, dominant-side peak angular velocities increased as ball speed increased from slow to fast: peak wrist flexion (118%), elbow flexion (176%), trunk rotation (99%), hip extension (143%), knee extension (56%), and plantarflexion (87%). Most kinematic variables changed as forehand ball speed changed; however, some variables changed more than others, indicating that range of motion and angular velocity for some joints may be more closely related to post-impact ball speed than for other joints.     

Kinematic Patterns Associated with the Vertical Force Produced during the Eggbeater Kick

The purpose of this study was to determine the kinematic patterns that maximized the vertical force produced during the water polo eggbeater kick. Twelve water polo players were tested executing the eggbeater kick with the trunk aligned vertically and with the upper limbs above water while trying to maintain as high a position as possible out of the water for nine eggbeater kick cycles. Lower limb joint angular kinematics, pitch angles and speed of the feet were calculated. The vertical force produced during the eggbeater kick cycle was calculated using inverse dynamics for the independent lower body segments and combined upper body segments, and a participant-specific second-degree regression equation for the weight and buoyancy contributions. Vertical force normalized to body weight was associated with hip flexion (average, r = 0.691; maximum, r = 0.791; range of motion, r = 0.710), hip abduction (maximum, r = 0.654), knee flexion (average, r = 0.716; minimum, r = 0.653) and knee flexion-extension angular velocity (r = 0.758). Effective orientation of the hips resulted in fast horizontal motion of the feet with positive pitch angles. Vertical motion of the feet was negatively associated with vertical force. A multiple regression model comprising the non-collinear variables of maximum hip abduction, hip flexion range of motion and knee flexion angular velocity accounted for 81% of the variance in normalized vertical force. For high performance in the water polo, eggbeater kick players should execute fast horizontal motion with the feet by having large abduction and flexion of the hips, and fast extension and flexion of the knees.     

Effects of changing speed on knee and ankle joint load during walking and running

Joint moments can be used as an indicator of joint loading and have potential application for sports performance and injury prevention. The effects of changing walking and running speeds on joint moments for the different planes of motion still are debatable. Here, we compared knee and ankle moments during walking and running at different speeds. Data were collected from 11 recreational male runners to determine knee and ankle joint moments during different conditions. Conditions include walking at a comfortable speed (self-selected pacing), fast walking (fastest speed possible), slow running (speed corresponding to 30% slower than running) and running (at 4 m · s^?1 ± 10%). A different joint moment pattern was observed between walking and running. We observed a general increase in joint load for sagittal and frontal planes as speed increased, while the effects of speed were not clear in the transverse plane moments. Although differences tend to be more pronounced when gait changed from walking to running, the peak moments, in general, increased when speed increased from comfortable walking to fast walking and from slow running to running mainly in the sagittal and frontal planes. Knee flexion moment was higher in walking than in running due to larger knee extension. Results suggest caution when recommending walking over running in an attempt to reduce knee joint loading. The different effects of speed increments during walking and running should be considered with regard to the prevention of injuries and for rehabilitation purposes.     

落地侧切动作对下肢关节的影响与分析

目的:确定运动员在落地后即刻启动完成侧切变向(LSC)动作的下肢踝、膝和髋三关节矢状面的运动学和动力学特点,并与平地跑动侧切变向(SC)对比分析、探讨这些差异对下肢关节造成的影响。方法:以14名高水平足球运动员为背景的大学生完成落地侧切和平跑侧切动作时的下肢运动学和动力学数据进行采集与分析。结果:LSC动作的踝、膝关节ROM和关节角速度显著增加,髋关节ROM则呈相反趋势(P<0.05或P<0.01);LSC的踝、膝和髋关节力矩峰值,踝、髋关节功率峰值呈现显著大于SC(P<0.01),膝关节功率峰值小于SC(P<0.05);LSC在水平向后、垂直向上地反峰值及峰值加载率有明显的增加(P<0.01),水平向右地反无明显差异(P>0.05)。结论:LSC虽然略降低了膝关节功率峰值,但其余所有运动学、动力学及GRF都预示其下肢关节所承受的损伤风险更高,尤其是踝关节和膝关节。踝关节的高功率和跖屈肌的持续紧张、伸膝力矩和三维地反的显著升高,使得该动作比公认高损伤风险的平跑侧切损伤风险几率更大。     

跑步疲劳进程中下肢生物力学模式的非线性变化研究

目的:确定跑步疲劳进程中下肢生物力学模式的变化,包括垂直和前后地面反作用力(ground reaction force,GRF)、垂直地面反作用力(vertical ground reaction force,vGRF)负载率、关节力学和刚度。方法:14名男性受试,采用Vicon红外摄像头和Bertec三维测力跑台,每隔2 min采集受试疲劳干预中的15 s GRF数据以及标记点轨迹。受试需穿着统一的跑鞋在测力跑台以恒速3.33 m/s跑至疲劳。满足以下标准时,干预结束:1)最大心率大于当下年龄的90%;2)受试不能继续跑步。对比受试跑至疲劳进程中4个时刻(疲劳前、33%、67%和100%)的着地冲击和下肢三关节触地角度、最大角度、关节活动度、角度变化量、关节蹬伸力矩和刚度等特征,采集并分析受试安静状态、疲劳后即刻、疲劳后4 min、疲劳后9 min的血乳酸浓度。结果:与疲劳前相比,1)血乳酸浓度在疲劳后即刻、疲劳后4 min和疲劳后9 min均显著增加;2)垂直/前后矢状轴GRF和vGRF负载率等参数在疲劳干预过程中均未观察到显著性变化;3)髋关节活动度在疲劳过程的33%、67%和100%时刻显著增加,膝关节活动度在67%时刻显著增加;4)踝关节运动学及踝、膝和髋关节的蹬伸力矩峰值均无变化;5)垂直刚度在67%和100%时刻显著降低。结论:疲劳干预过程中,GRF特征参数均没有明显变化,但是观察到下肢运动学和动力学模式的非线性改变。特别是从疲劳干预中期开始,人体下肢通过增加髋、膝关节活动度并减小垂直刚度实现“软着陆”策略,维持相似的冲击力特征,以减小长时间跑步可能带来损伤的风险。     

Greater lower limb flexion in gymnastic landings is associated with reduced landing force: a repeated measures study

High impact forces during gymnastic landings are thought to contribute to the high rate of injuries. Lower limb joint flexion is currently limited within gymnastic rules, yet might be an avenue for reduced force absorption. This study investigated whether lower limb flexion during three gymnastic landings was related to force. Differences between landings were also explored. Twenty-one elite women's artistic gymnasts performed three common gymnastic techniques: drop landing (DL), front and back somersaults. Ankle, knee, and hip angles, and vertical ground reaction force [(vGRF) magnitude and time to peak], were measured using three-dimensional motion analysis and force platform. The DL had significantly smaller peak vGRF, greater time to peak vGRF and larger lower limb flexion ranges than landing from either somersault. Peak vGRF and time to peak vGRF were inversely related. Peak vGRF was significantly reduced in gymnasts who landed with greater hip flexion, and time to peak was significantly increased with increasing ankle, knee, and hip flexion. Increased range of lower limb flexion should be encouraged during gymnastic landings to increase time to peak vGRF and reduce high impact force. For this purpose, judging criteria limitations on lower limb flexion should be reconsidered.     

北狮运动员膝关节屈伸肌群等速向心收缩生物力学特性的研究

目的:通过对湖南师范大学9名北狮运动员双侧膝关节屈伸肌群进行等速测试,为揭示该项运动膝关节肌群收缩的生物力学特性提供实验依据。方法:采用BIODEX SYSTEM 3等速测试系统对湖南师范大学北狮运动员膝关节屈伸肌群进行等速测试,测试指标为峰力矩、相对峰力矩、屈伸肌峰力矩比、平均功率及做功疲劳度。结果:1)北狮运动员双侧膝关节屈伸肌峰力矩和相对峰力矩随测试速度的增加呈递减趋势;2)狮头狮尾屈伸肌群峰力矩比值和做功疲劳度无显著性差异;3)狮头狮尾左右膝关节同一肌群峰力矩无显著性差异。结论:舞狮运动员膝关节肌群峰力矩变化随测试速度的增加而减少,平均功率呈现随运动速度的增加而增加,到达一定速度后随速度的增加而减少的特征。     

Influence of a horizontal approach on the mechanical output during drop jumps

This study investigated the influence of a horizontal approach to mechanical output during drop jumps. Participants performed drop jumps from heights of 15, 30, 45, and 60 cm with zero, one, two, and three approach steps. The peak summed power during the push-off phase changed quadratically across heights (6.2 +/- 0.3, 6.7 +/- 0.4, 6.4 +/- 0.4, and 6.0 +/- 0.4 kW, respectively) driven by the ankle joint response. Summed peak power was 10% greater with an approach attributed to the knee joint response. Downward phase dorsiflexion (31%), knee flexion (35%), and peak vertical force (32%) increased with drop heights. Vertical approach force (22%) increased, while knee flexion (11%) and downward duration (17%) decreased. An approach may improve drop jump training for explosive tasks.     

Contribution of the lower extremity joints to mechanical energy in running vertical jumps and running long jumps

The energy contribution of the lower extremity joints to vertical jumping and long jumping from a standing position has previously been investigated. However, the resultant joint moment contributions to vertical and long jumps performed with a running approach are unknown. metatarsophalangeal joint to these activities has not been investigated. The objective of this study was to determine the mechanical energy contributions of the hip, knee, ankle and metatarsophalangeal joints to running long jumps and running vertical jumps. A sagittal plane analysis was performed on five male university basketball players while performing running vertical jumps and four male long jumpers while performing running long jumps. The resultant joint moment and power patterns at the ankle, knee and hip were similar to those reported in the literature for standing jumps. It appears that the movement pattern of the jumps is not influenced by an increase in horizontal velocity before take-off. The metatarsophalangeal joint was a large energy absorber and generated only a minimal amount of energy at take-off. The ankle joint was the largest energy generator and absorber for both jumps; however, it played a smaller relative role during long jumping as the energy contribution of the hip increased.