Signalling of muscle force by Golgi tendon organs during exercise and fatigue

当一个人在运动过程中感到疲惫和肌肉疲劳时，被抬着的物体感觉更重，需要肌肉努力的任务变得更加困难，这是一种常见的经验。肌肉力量的感觉取决于两个因素。一种是完成一项任务所需的努力的感觉，它是在中枢神经系统中产生的。另一种是肌肉实际产生的力觉，是由被称为高尔基肌腱器官的感觉感受器发出的信号在肌肉本身产生的。肌肉力量的感觉和物体的重量是这两种感觉结合的结果，但每一种感觉的贡献是未知的。该项目的目的是确定疲劳肌肉的力觉障碍是否是由于肌腱器官发出肌肉实际产生的力量的信号方式的变化造成的。这对于了解运动后和疾病状态下力觉是如何被干扰的，以及理解肌肉力量在日常情况下的正常感觉方式将是重要的。运动后的力觉障碍将被记录在人类受试者身上，方法是要求受试者在只锻炼一条肢体之前和之后，在两只手臂或双腿上产生他们认为相等的力量。力量估计的错误将表现为两个肢体之间的不匹配。人体实验的困难在于，肌腱器官产生的信号不能直接测量，只能推断，可能是错误的。这一困难将通过在麻醉动物中直接测量肌腱器官活动来克服，在麻醉动物中，肌肉将受到电刺激来执行类似于人类实验中的运动。肌腱器官信号的变化将被认为意味着人类的类似变化可能是导致力觉障碍的原因。在进一步的实验中，这些变化的机制将被探索。

It is a common experience for objects being carried to feel heavier and tasks needing muscular effort to become more difficult as one becomes tired and the muscles fatigue during exertion. The sensation of muscle force depends on two factors. One, a sense of the effort required to perform a task, is generated in the central nervous system and. The other, a sense of the force actually developed by the muscles, is generated in the muscles themselves by signals from sensory receptors called Golgi tendon organs. The sensation of muscle force and the heaviness of objects results from a combination of both senses, but the contribution of each is unknown. The aim of the project is to determine whether the disturbance of force sense in fatigued muscles results from changes in the way tendon organs signal the actual force developed by the muscles. This will be important for understanding how force sense is disturbed following exercise and in disease states, and for understanding the normal way muscle force is sensed in everyday situations. Disturbances of force sense after exercise will be documented in human subjects by asking them to generate what they perceive to be equal forces in both arms or legs, before and after one limb only is exercised. Errors in force estimation will show up as mismatches between the two limbs. The difficulty with human experiments is that the signals generated by tendon organs cannot be measured directly, but only inferred, perhaps wrongly. This difficulty will be overcome by measuring tendon organ activity directly in anaesthetised animals, where the muscles will be electrically stimulated to perform exercise similar to that in the human experiments. A change in tendon organ signalling will be taken to mean that similar changes in humans could be responsible for disturbances of force sense. In further experiments, the mechanism of the changes will be explored.