Human hypoglossal motor unit activities in exercise.
Human hypoglossal motor unit activities in exercise.
复制标题
人体运动中舌下运动单位的活动。
DOI：
10.1113/jphysiol.2013.252452
复制
发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Bailey,EFiona
中科院分区：
文献类型：
--
作者：
Walls,ClintonE;Laine,ChristopherM;Kidder,IanJ;Bailey,EFiona
关键点·运动单元(MU)是产生力量的基本要素。在这里，我们记录了在静息和大负荷运动中呼吸时，呼吸道扩张肌膝舌肌(GG)的MU活动。·基于我们的观察，我们认为，尽管具有不同程度的呼吸调节，但在健康年轻人的GG运动神经元池中，紧张性MU活动是优势活动。我们发现，运动引起的呼吸驱动的增加与GG肌电活动的增加有关，这主要是由于先前沉默的MU的重新招募以及已经活跃的MU的放电行为转变为吸气相依赖的爆发。·这种呼气相关的抑制可能继而出现于运动相关的运动神经元兴奋性的中枢增强，从而放大了对传入输入的反应。摘要膝舌肌(GG)被认为是舌头的主要突出肌肉，扩张和僵硬咽呼吸道。我们在自行车测功机上记录了进行递增强度运动的健康成年人的整体肌肉和单运动单位(MU)活动。将钨微电极经皮植入11名20~40岁受试者的GG，记录静息和负荷递增至300W时的肌电活动和肺通气量(VI)。呼吸驱动力的增加与INVI、平均吸气流量(Vt/Ti)和GG EMG活动的主相成分增加有关。相比之下，随着运动强度的增加，个别MU典型地表现出与呼气相关的放电减少。我们认为，MU活性的下降可能发生在来自肺/胸壁的传入反馈之后，而对大强度运动中产生的更负的吸气气道压力的补偿主要是通过招募以前沉默的MU来实现的。
Key points•Motor units (MUs) are the fundamental element of force generation. Here we document the MU activities of the airway dilator muscle genioglossus (GG) during breathing at rest and in heavy exercise.•Based on our observations we suggest that tonic MU activity, albeit with varying degrees of respiratory modulation, is the preponderant activity in the GG motoneuron pool of healthy young adults at rest in the upright position.•Second, we show that exercise‐driven increases in respiratory drive are associated with increased GG electromyographic activity principally due to recruitment of previously silent MUs and to a shift in the firing behaviour of already active MUs to inspiratory phase‐dependent bursting.•Such expiration‐related inhibition may arise secondary to an exercise‐related central enhancement of motoneuron excitability that amplifies the response to afferent input.AbstractThe genioglossus (GG) muscle is considered the principal protruder muscle of the tongue that dilates and stiffens the pharyngeal airway. We recorded whole muscle and single motor unit (MU) activities in healthy adults performing progressive intensity exercise on a cycle ergometer. Tungsten microelectrodes were inserted percutaneously into the GG of 11 subjects (20–40 years) to record electromyographic (EMG) activities and pulmonary ventilation (VI) at rest and at workload increments up to 300 W. Increases in respiratory drive were associated with increases inVI, mean inspiratory flow (Vt/Ti) and tonic and phasic components of the GG EMG activity. In contrast, individual MUs typically showed expiration‐related decreases in firing as exercise intensity increased. We suggest the decrease in MU activity may occur secondary to afferent feedback from lungs/chest wall and that compensation for more negative inspiratory airway pressures generated during heavy exercise occurs primarily via recruitment of previously silent MUs.