Stress Similarity and the Biomechanics of Terrestrial Locomotion in Mammals

动物用它们的四肢产生并传递与之相关的力 在重力作用下移动和支撑。 这些 力对肌肉的进化有重要影响 和骨骼设计，以及对这些适应性反应， 组织对机械负荷变化的反应。 机械要求 对于运动支撑，反过来又会影响运动者消耗的能量 动物在运动活动，并规定其限制 性能 通过比较不同大小的动物的运动机制 物种，比维纳博士试图建立一般原则， 决定了自然选择如何偏爱有效的策略， 陆地哺乳动物的重力支持。 一个这样 策略似乎是规则的肢体大小依赖性变化 姿势 通过采取更直立的姿势，较大的动物降低 肌肉和骨骼必须传递的力量， 运行. 这种力量的减少抵消了 更大的动物，以支持他们的体重，由于大小的影响， 他们的组织的面积与体积的比例。 其基础 机械约束是运动应力的要求， （每单位面积的力）作用于骨骼和肌肉组织， 在每个组织强度的安全范围内。 “安全” 这些组织的“因子”似乎大约是他们的三分之一。 实力 本研究具有实用意义， 骨骼和肌肉适应性反应的机制和能力 物理需求的变化。 这一点很重要， 与体育活动有关的体能训练， 治疗方案，从致残性身体伤害中恢复， 外科肌肉/肌腱移植策略，以克服运动 缺陷，以及评估身体的重要性， 运动与年龄相关的骨质流失。

Animals use their limbs to generate and transmit forces associated with movement and suppport against the force of gravity. These forces are an important influence both on the evolution of muscle and bone design, as well as on the adaptive response of these tissues to changes in mechanical loading. Mechanical requirements for locomotor support, in turn, affect the energy expended by an animal during locomotor activity and dictate the limits of its performance. By comparing the mechanics of locomotion of broadly differing sized species, Dr. Biewener seeks to establish general principles that govern how natural selection has favored strategies for effective support of gravitational loads in terrestrial mammals. One such strategy appears to be regular size-dependent change in limb posture. By adopting a more upright posture, larger animals lower the forces that must be transmitted by their muscles and bones when running. This decrease in force offsets the diminished ability of larger animals to support their weight due to the effect of size on the area to volume scaling of their tissues. Underlying this mechanical constraint is the requirement that locomotor stresses (force per unit area) acting in bone and muscle tissue be kept within a safe fraction of each tissue's strength. The "safety factor" of these tissues appears to be roughly one-third of their strength. This research has applied significance relating to the functional mechanism and capacity of bone and muscle to respond adaptively to changes in physical requirements. This is important in terms of physical training associated with sports-related activity, physical therapy programs for recovery from disabling physical injury, for surgical muscle/tendon transplantation strategies to overcome motor deficits, as well as for evaluating the importance of physical exercise in relation to age-related bone loss.