Muscle viscosity as a protective mechanism for absorbing mechanical shock

描述(申请人提供)：肌肉在时间和空间上重新分配机械冲击能量的能力和卸载骨骼关节的能力在体育活动中至关重要，如跑步和跳跃、踢足球、摔跤等。在这些活动中发生的影响可能超过关节之间的软骨垫所能承受的水平，这些软骨垫可以缓冲伴随着日常活动而产生的适度影响，如步行。我们假设，消耗外界冲击的机械能以吸收机械冲击是骨骼肌的基本功能，而骨骼肌的粘度是一个可变参数，可以通过改变收缩肌肉的张力来自动控制。我们进一步假设，在生物进化的过程中，肌肉已经发展了吸收冲击的能力，允许生命从海洋移动到陆地，从流体动力学环境移动到空气动力学环境，肌肉骨骼系统的加载条件截然不同。到目前为止，还没有可用的实用工具来评估肌肉的动态粘度。我们建议开发一种紧凑、易用的在体骨骼肌粘弹性评估仪器，用于探索肌肉减少外部冲击对骨骼和关节的有害影响的机制和能力。该装置将基于使用声辐射力脉冲在组织中产生局部位移，并将在松弛过程中使用基于互相关的方法跟踪所产生的位移。该项目的目标包括在肌肉模体上对开发的设备进行台架测试，并在有限的运动员群体中进行初步的初步研究，以证明拟议技术的可行性。体内获得的实验数据将与肌肉粘度的分子机制数学模型的理论预测进行比较。肌肉粘度的定量评估可能会对医学生物力学和运动医学中的许多问题有所启发。肌肉粘弹性定量评估设备可以评估的肌肉疾病清单包括肌肉营养不良、运动神经元疾病、炎性和代谢性肌病等。监测肌肉粘度有助于预测关节疾病，如肌腱炎、滑囊炎和骨关节炎，并降低骨质疏松性骨折的可能性。这种设备的潜在应用领域包括一般临床应用；康复和职业医学；运动医学：评估运动员的肌肉状况和表现；老年学：评估肌肉在衰老过程中的变化，特别是在骨质疏松症和骨关节炎期间肌肉骨骼系统完全减弱后的变化，以及预防效果的评估。

DESCRIPTION (provided by applicant): The ability of muscle to redistribute the energy of mechanical shock in time and space and unload skeletal joints is of key importance in physical activities, such as running and jumping, playing soccer, wrestling, etc. The impacts that occur during such activities may exceed the level that can be tolerated by cartilage pads between joints which cushion the moderate impacts accompanying mundane activities such as walking. We hypothesize that dissipation of mechanical energy of external impacts to absorb mechanical shock is a fundamental function of skeletal muscle and the viscosity of the skeletal muscle is a variable parameter which can be voluntarily controlled by changing the tension of the contracting muscle. We further hypothesize that an ability of muscle to absorb shock had been developed in the course of biological evolution, allowing the life to move from the ocean to land, from hydrodynamic to aerodynamic environment with dramatically different loading conditions for musculoskeletal system. To date there are no available practical tools for assessment of muscle dynamic viscosity. We propose to develop a compact and easy-to-use instrument for assessment of viscoelastic properties of skeletal muscle in vivo that can be used in exploring the mechanism and the ability of muscle in reducing the harmful effect of external impacts on bones and joints. The device will be based on the use of an acoustic radiation force impulse to generate localized displacements in tissue and the resulting displacements will be tracked during relaxation using cross-correlation based methods. The goals of this project include bench-testing of the developed device on muscle phantoms and conducting preliminary pilot study on a limited group of athletes demonstrating feasibility of the proposed technology. Experimental data obtained in vivo will be compared with theoretical predictions of the mathematical model for the molecular mechanism of the muscle viscosity. Quantitative assessment of muscle viscosity may shed light to many problems of medical biomechanics and sports medicine. The list of muscle disorders that can be assessed by a device for quantitative assessment of muscle viscoelasticity includes muscle dystrophy, motor neuron diseases, inflammatory and metabolic myopathies and many more. Monitoring muscle viscosity could help in anticipating joint diseases, such as tendonitis, bursitis and osteoarthritis and decreasing the probability of osteoporotic bone fracture. The fields of potential applications of such device include general clinical applications; rehabilitation and occupational medicine; sports medicine: assessment of muscle condition and performance in athletes; gerontology: assessment of muscle changes in aging, particularly following total weakening of musculoskeletal system during osteoporosis and osteoarthritis, and estimation of the prophylactics efficacy.