Human muscle fatigue: responsiveness of motoneurons and central contributions to the loss of muscle power

人体肌肉疲劳：运动神经元的反应性和对肌肉力量损失的主要贡献

• 批准号: 435912-2013
• 负责人: Mcneil, Christopher
• 金额: $ 2.11万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=683117
• 关键词: Human; muscle; fatigue; responsiveness; motoneurons

My research program uses innovative techniques to advance our understanding of human neuromuscular physiology, with emphasis on fatigue and aging. Fatigue produced by activity is a common experience for healthy people and is magnified in many conditions such that the performance of even day-to-day tasks can be limited, particularly in the elderly. One theme of experiments is to investigate the mechanism(s) of the reduction in spinal motoneuron excitability caused by fatigue which is described in a recent series of papers (McNeil et al. 2009, 2011a,b,d). By combining multiple stimulation techniques (transcranial magnetic stimulation, corticospinal tract stimulation, peripheral nerve stimulation), I will investigate measures of motoneuron excitability in an effort to localize the mechanism(s). Muscle contraction is controlled by motoneuron output so an improved understanding of motoneuron properties is critical to advance our knowledge of the motor system. The second theme of experiments is dedicated to the investigation of muscle power generated by shortening contractions with a fixed-load. Muscle fatigue has been studied sparingly using this most functionally-relevant contraction type. My earlier work (McNeil & Rice 2007) showed that muscles of elderly men are more fatigable in this situation, which is the opposite finding to numerous studies that used static tasks where muscle length was fixed. The work also suggested indirectly that fatigue occurs almost exclusively within the periphery (the muscle itself). A similar view was held about static tasks for many years but, in the last 15 years, it has been shown that 25-66% of force loss can be due to failure within the central nervous system. Using novel techniques and models such as aging and sex, I intend to explore central and peripheral contributions to fatigue developed by shortening contractions with a fixed-load. An improved understanding of limits to muscle power has implications across the full spectrum of activity, from simple daily tasks to voluntary exercise or training.

我的研究项目使用创新技术来促进我们对人类神经肌肉生理学的理解，重点是疲劳和衰老。运动产生的疲劳是健康人的一种常见体验，在许多情况下会被放大，以至于即使是日常工作也可能受到限制，特别是在老年人身上。实验的一个主题是研究疲劳引起的脊髓运动神经元兴奋性降低的机制(S)，这在最近的一系列论文中进行了描述(麦克尼尔等人。2009、2011a、b、d)。通过结合多种刺激技术(经颅磁刺激、皮质脊髓束刺激、周围神经刺激)，我将研究运动神经元兴奋性的测量方法，以努力定位其机制(S)。肌肉收缩是由运动神经元的输出控制的，因此对运动神经元特性的更好的理解对于促进我们对运动系统的了解是至关重要的。实验的第二个主题致力于研究在固定负荷下缩短收缩所产生的肌肉力量。使用这种与功能最相关的收缩类型来研究肌肉疲劳一直很少见。我之前的工作(麦克尼尔和赖斯2007)表明，在这种情况下，老年男性的肌肉更容易疲劳，这与许多使用固定肌肉长度的静态任务的研究相反。这项研究还间接地表明，疲劳几乎完全发生在外周(肌肉本身)。许多年来，人们对静态任务持类似的观点，但在过去的15年里，有研究表明，25%-66%的力量损失可能是由于中枢神经系统内的故障造成的。利用新的技术和模型，如衰老和性别，我打算探索中枢和外周对疲劳的贡献，这些因素是通过固定负荷缩短收缩而形成的。对肌肉力量极限的更好理解涉及到从简单的日常任务到自愿锻炼或训练的所有活动范围。