Roberts Thomas J
Oregon State University, Department of Zoology, 3029 Cordley Hall, Corvallis, OR 97331-2914, USA.
Comp Biochem Physiol A Mol Integr Physiol. 2002 Dec;133(4):1087-99. doi: 10.1016/s1095-6433(02)00244-1.
The mechanical roles of tendon and muscle contractile elements during locomotion are often considered independently, but functionally they are tightly integrated. Tendons can enhance muscle performance for a wide range of locomotor activities because muscle-tendon units shorten and lengthen at velocities that would be mechanically unfavorable for muscle fibers functioning alone. During activities that require little net mechanical power output, such as steady-speed running, tendons reduce muscular work by storing and recovering cyclic changes in the mechanical energy of the body. Tendon stretch and recoil not only reduces muscular work, but also allows muscle fibers to operate nearly isometrically, where, due to the force-velocity relation, skeletal muscle fibers develop high forces. Elastic energy storage and recovery in tendons may also provide a key mechanism to enable individual muscles to alter their mechanical function, from isometric force-producers during steady speed running to actively shortening power-producers during high-power activities like acceleration or uphill running. Evidence from studies of muscle contraction and limb dynamics in turkeys suggests that during running accelerations work is transferred directly from muscle to tendon as tendon stretch early in the step is powered by muscle shortening. The energy stored in the tendon is later released to help power the increase in energy of the body. These tendon length changes redistribute muscle power, enabling contractile elements to shorten at relatively constant velocities and power outputs, independent of the pattern of flexion/extension at a joint. Tendon elastic energy storage and recovery extends the functional range of muscles by uncoupling the pattern of muscle fiber shortening from the pattern of movement of the body.
在运动过程中，肌腱和肌肉收缩元件的机械作用通常被独立考虑，但在功能上它们紧密结合。肌腱可以增强各种运动活动中的肌肉性能，因为肌肉 - 肌腱单元以单独的肌肉纤维在机械上不利的速度缩短和延长。在需要很少净机械功率输出的活动中，如匀速跑步，肌腱通过储存和恢复身体机械能的循环变化来减少肌肉做功。肌腱的拉伸和回弹不仅减少了肌肉做功，还使肌肉纤维能够近乎等长地运作，在此情况下，由于力 - 速度关系，骨骼肌纤维会产生高力量。肌腱中的弹性能量储存和恢复也可能提供一种关键机制，使单个肌肉能够改变其机械功能，从匀速跑步时的等长力产生者转变为加速或上坡跑等高功率活动中的主动缩短功率产生者。对火鸡肌肉收缩和肢体动力学的研究证据表明，在跑步加速过程中，随着步骤早期肌腱拉伸由肌肉缩短提供动力，功直接从肌肉转移到肌腱。肌腱中储存的能量随后被释放，以帮助为身体能量的增加提供动力。这些肌腱长度变化重新分配了肌肉功率，使收缩元件能够以相对恒定的速度和功率输出缩短，而与关节处的屈伸模式无关。肌腱弹性能量储存和恢复通过将肌肉纤维缩短模式与身体运动模式解耦，扩展了肌肉的功能范围。
