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

当一个人在劳累和肌肉疲劳时，搬运的物品会感到更重，需要肌肉努力的任务会变得更困难，这是一种常见的体验。肌肉力量的感觉取决于两个因素。一种是完成任务所需的努力感，由中枢神经系统产生。另一种是由肌肉产生的力量感，它是由肌肉本身通过被称为高尔基肌腱器官的感觉受体发出的信号产生的。肌肉力量的感觉和物体的重量是两种感觉的结合，但每种感觉的作用是未知的。该项目的目的是确定疲劳肌肉的力感紊乱是否源于肌腱器官发出肌肉实际发力信号的方式的变化。这对于理解在运动后和疾病状态下力感是如何被干扰的，以及理解在日常情况下肌肉力的正常感知方式将是重要的。运动后的力感干扰将在人类受试者中记录下来，方法是要求他们在运动前和运动后，在双臂或双腿上产生他们认为相等的力。力估计的误差将表现为两肢之间的不匹配。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，而且可能是错误的。这一困难将通过直接测量麻醉动物的肌腱器官活动来克服，在麻醉动物中，肌肉将被电刺激以进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导致力感的干扰。在进一步的实验中，将探索这种变化的机制。

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.