【作者】 傅维杰；

【导师】 刘宇；

【作者基本信息】 上海体育学院 ， 运动人体科学， 2011， 博士

【摘要】 研究目的:跑跳等动作人体下肢所承受的被动冲击力可以对人体肌肉-骨骼系统造成影响,但这并不意味着冲击力就是造成运动损伤的根本原因,近期的研究显示,冲击力的频率(10-20Hz)与人体软组织固有频率(5-65Hz)的重叠而引起的共振是导致软组织损伤的重要因素。本研究以主动落地反跳和被动着地两种常见的落地方式作为目标动作,探讨人体在不同着地策略过程中,运动鞋和紧身裤这两种外加因素对冲击力特征、下肢软组织振动和主要肌群活动的影响,找寻它们之间的相互关系。具体包括:(1)探讨穿着不同运动装备在两种落地方式下的基本生物力学特征和运动表现;(2)比较不同运动鞋对于冲击力(幅度、时频域特征)和人体下肢软组织特性(幅度、时频域和阻尼特征)的影响,以及相应肌群所做出的反应(预激活、后激活和共激活等),进一步量化运动鞋对于响应冲击进而影响下肢肌肉功能的作用;(3)比较不同紧身裤对于冲击力和肌肉活化的影响,特别是人体下肢软组织的力学特性(频率、阻尼等)以及振动传递特性的变化,明确紧身装备与肌肉调节和适应功能之间的相互关系,理解紧身装备能够减少能量消耗、影响肌肉疲劳、最终提高运动表现的内在机理。研究方法:选取12名体教专业球类专项男性运动员作为受试者,运动鞋选取国际某知名品牌、鞋中底具备强缓冲性能的篮球鞋作为测试用鞋,并辅以对照鞋。紧身装备选取国际某知名品牌的紧身短裤作为测试紧身装备,同时辅以对照组。每位受试者在自制可调节高度的翻板器上完成包括三种下落高度(30 cm、45 cm和60 cm)和两种下落方式(主动落地反跳:Drop Jump,DJ和被动着地:Passive Landing,PL)的测试。利用红外摄像捕捉系统(Vicon,UK)、测力台(Kistler,Switzerland)、加速度信号分析系统(Biovision,Germany)、肌电图信号分析系统(Biovision)、高速摄像系统(Motion Pro X-4,USA)同步采集下肢三关节(髋、膝、踝)的运动学/动力学、冲击力特征(地面反作用力)、软组织加速度信号(股四头肌和股后肌群)、下肢各主要肌群EMG信号(胫骨前肌:TA、腓肠肌外侧头:LG、股直肌:RF、股外侧肌:VL和股二头肌:BF),并辅以Visual3D、DASYLab等信号分析软件对所获得的数据进行后期处理和解析。研究结果:(1)关节的运动学/动力学:篮球鞋组的踝关节角度和紧身裤组的髋关节角度在DJ触地瞬间显著大于控制组;篮球鞋组的踝关节和紧身裤组的髋关节最小/最大角度在45cm和60cm下落时中均显著增加,且踝、髋最小角速度也变小。但无论是篮球鞋还是紧身裤都没有对DJ时离地速度和腾空高度产生影响。且穿着篮球鞋和紧身裤并没有改变关节力矩、关节最大功率和刚度。(2)冲击力特征:DJ中篮球鞋并没有对冲击力峰值、最大负载率、冲击力频率产生影响;但PL时,无论是30cm、45cm还是60cm下落,穿着篮球鞋均能够显著减小冲击力峰值、最大负载率、输入频率和鞋跟加速度的频率(fGRF和fshoe)。同时,与对照鞋相比,高度的改变对于冲击力频率的影响,篮球鞋相对更小。(3)软组织振动特性:穿着紧身裤显著减小两种落地方式下下肢软组织振动的最大振幅以及阻尼,同时在DJ60过程中,紧身裤组股后肌的共振频率显著大于控制组,同时在DJ45、DJ60和PL60时,紧身裤组股四头肌以及股后肌的共振传递性(Hmax)显著小于控制组。(4)肌肉活化特性:无论是预激活、后激活还是缓冲激活,相同高度下,PL各下肢肌肉的活化程度显著小于DJ情况。在DJ时紧身裤显著减小了RF和VL的预激活、后激活和蹬伸激活以及部分高度下BF的后激活和蹬伸激活,同时减小了部分高度下RF、VL和BF预激活的中位频率;而穿着篮球鞋在PL时显著减小了TA和LG的后激活以及部分高度下RF、VL和BF的后激活和缓冲激活,同时影响了PL30、PL60时VL、LG和RF的预激活和后激活的中位频率。主要结论:(1)篮球鞋和紧身裤改变了主动落地反跳过程中下肢关节运动学的部分结果(触地角度、最大/最小角度等),但未对力矩变化量、刚度、功率输出、反跳高度等力量输出参数产生显著变化。(2)主动落地反跳时,篮球鞋的介入并没有明显改变冲击力的各种特征参数;相反被动着地时,穿着篮球鞋显著降低了冲击力、负载率和鞋跟加速度的峰值,减小冲击频率,并使得高度因素对于冲击力各项特征的影响更小。提示当人体未完全(或较少)控制着地状态时,运动鞋的重要性就会突显,即:在发挥其缓冲避震功能的同时改变了输入于下肢各软组织振动系统的信号特征,减小冲击传递性,使软组织远离共振区域,达到了本需要通过额外肌肉活化才能达到的减小振动的作用。(3)紧身裤的介入显著减小股四头肌和股后肌群软组织振动的振幅并增加各自的阻尼系数,同时相比改变振动系统的频率,更多情况下紧身裤可以通过衰减系统的共振来达到影响软组织振动特性的目的,避免下肢与反复冲击力产生共振,并有条件地减小肌肉的预激活和后激活,对能量消耗、运动舒适性和预防冲击损伤带来积极的效果。更多还原

【Abstract】 Objective: During running, jumping and other human movements, lower limb exposure to passive impact can affect on human muscle - skeletal system, but that does not mean the impact force is the fundamental causes of sports injuries. Recent studies have shown that the resonance which is created by the overlapped frequency between that of impact forces (10-20Hz) and the natural frequency of soft tissues (5-65Hz) is an essential cause for soft tissue injury. In this study, drop jumps and passive landings which are two common ways were selected as target movements. The aim of this study was to explore the effect of basketball shoes and compression shorts on impact forces, soft tissue vibrations, muscle activity, and their possible interactions during active landing (drop jump, DJ) and passive landing (PL). Including: (1) to discuss the basic biomechanical characteristics and exercise performance by wearing two different sports equipments during two landing activities. (2) to compare the influence of different shoes (amplitude, time-frequency domain features) and lower limb soft tissue characteristics (amplitude, frequency and damping characteristics of the time) effects, and the corresponding muscle’s response (pre- activataion and post- activation and co-activation, etc.), we can further quantify the impact of sports shoes for the response and thus affect the lower limb muscle function. (3) to compare the effect of compression shorts on impact, muscle activation, mechanical properties (frequency, damping, etc.) of soft tissues in lower limb and changes in transfer characteristics of vibration. We also determined the interrelationship between compression apparel and adaptation function of muscle, in order to further comprehend the internal mechanisms for reducing energy consumption, affecting muscle fatigue and ultimately improving the performance by wearing compression equipments.Methods: 12 male professional athletes specialized in physical education were selected as subjects. A well-known international brand of basketball shoe was chosen in the testing with strong cushion capacity of shoes. Shoe in control condition (CC) was also arranged. Compression shorts (CS), the products under a well-known international brand, were elected as test equipments, and were also given corresponding control group. Each subject was required to stand on a custom-made device with adjustable height to complete two kinds of drop landings (drop jump and passive landing) from three heights (30 cm, 45 cm and 60 cm). Infrared camera capture system (Vicon, UK), force platform (Kistler, Switzerland), the acceleration signal analysis system (Biovision, Germany), EMG signal analysis system (Biovision), and high-speed camera system (Motion Pro X-4, USA) were synchronously to collected kinematics / dynamics of lower extremity (hip, knee, ankle), impact characteristics (ground reaction force), soft tissue acceleration signal (and the femoral quadriceps muscles), and EMG signals of major muscle groups (tibialis anterior: TA, gastrocnemius lateral head: LG, rectus femoris: RF, vastus lateralis: VL and biceps femoris: BF). Visual3D, DASYLab and other signal analysis software were also applied to process and analyse data.Results: (1) Joint kinematics/dynamics: Ankle angle in Bball group and hip angle in CS group were significantly larger than that of CC during the instantaneous moment of touchdown in DJ; minimum / maximum angle of ankle one in Bball group and hip one in CS showed an obvious increase during DJ from 45 cm and 60cm, and the minimum angle velocity of both ankle and hip joint decreased. However, neither Bball nor CS took effects on takeoff velocity and jump heights during DJs. In addition, no significant changes were found in joint torque, maximum power and stiffness of joints while wearing compression shorts and basketball shoes. (2) Characteristics of impact forces: during DJ, peak impact, maximum load rate and impact frequency were not be influenced by basketball shoes. However, during PL from all heights-30cm, 45cm and 60cm, wearing basketball shoes can significantly reduce the peak impact force, the maximum load rate, input frequency and frequency of the acceleration in heel (fGRF and fshoe). Meanwhile, compared with the CC, the effect of height on impact frequency of Bball group is relatively smaller. (3) Characteristics of soft tissue vibration: a significant decrease of maximum amplitude and vibration damping by wearing compression shorts was found in both landing styles. During DJ60, the resonant frequencies of hamstring muscles in CS condition were significantly greater than those in CC. For DJ45, DJ60, and PL60, the resonance transmissibility (Hmax) of both quadriceps femoris and hamstring muscles in CS condition was significantly lower than that in CC. (4) features of muscle activities: whether in pre-activation or post-activation periods, activation of the muscles in lower limb during PL was obviously less than that in DJ situation from the same drop height. During DJ, a significant decrease in EMG pre- / post-activation, as well as median frequency (MF) of the RF, VL, and BF was found in the CS condition. Meanwhile, a significant decrease in EMG post-activation of TA, LG, as well as RF and BF under certain drop heights was found in the Bball condition. Wearing basketball shoes also showed an influence on the MF of the VL, LG and RF during both pre- and post-activation.Conclusion: (1) Wearing basketball shoes and compression shorts can change partial kinematics results (touchdown angle, the maximum/minimum angle, etc.) of lower extremity joints during drop jumps. However, no significant differences were found in the strength output parameters, such as the variation of moment, stiffness, power output, and rebound height. (2) During active DJs, characteristic parameters of impact force can’t be significantly changed by the intervention of basketball shoes; while in condition of passive landing (PL), wearing basketball shoes can remarkably reduce the peak of impact, loading rate, acceleration and impact frequency, in addition, can minimize the effect of height on characteristic parameters of impact force. Reminder: we can highlight the essentiality of basketball shoes when people can’t control the motion of landing completely (or minor). In other words, wearing basketball shoes can alter signal features of soft tissue in lower limbs when exert the functions of buffering and anti-vibration. And with basketball shoes, we can also decline the transmissibility to keep the soft tissue away from the region of resonance. By doing this, effects, like reduced vibration, which should be achieved with extra muscle activations could be realized. (3) The intervention of compression shorts showed a significant decrease in vibration amplitude of quadriceps femoris and hamstring muscles, but an increase in damping factors of them. Compared with changing the frequency of vibration system, wearing compression shorts can affect vibration characteristics of soft-tissue via reducing the resonance of system which can also avoid the resonance between repetitive impacts and lower extremity in more cases, what’s more, benefit muscle pre- / post-activation, in order to bring in a positive effect on energy consumption, comfort and prevention of sports injuries.更多还原