MENTAL EFFORT EFFECT ON LARGE MUSCLE STRENGTHENING

精神努力对大肌力量的影响

• 批准号: 2879652
• 负责人: GUANG H YUE
• 金额: $ 22.11万
• 依托单位: CLEVELAND CLINIC FOUNDATION
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-27 至 2003-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2879652
• 关键词: biomechanics; brain electrical activity; clinical research; elbow; electroencephalography; electromyography; exercise; functional ability; functional magnetic resonance imaging; human old age (65+); human subject; leg; muscle contraction; muscle strength; neural information processing; neuromuscular function; psychomotor function

It is well known that to strengthen a muscle one should perform training involving heavy loads or resistance. Recently we have found that substantial voluntary strength gains can be achieved with training involving low resistance but strong mental effort. In contrast, individuals who trained with the same low-intensity contractions but with low mental effort had no improvement in strength. Based on these preliminary findings, we hypothesize that muscle strength improvements depend primarily on the level of mental effort during training, not the training intensity (resistance) per se. The reason that high-intensity training always increases strength is because mental effort is high during high-intensity muscle contractions. Aim 1 of the project is to compare the effects of training with different levels of mental effort on the improvement in muscle strength. Four groups of elderly subjects (greater than or equal to 65 years) will participate in a 12-week training study involving elbow-flexor muscles. One group will be trained with an intensity near the level of maximal voluntary contraction (MVC group); a second group will be trained with high mental-effort, low muscle-intensity elbow-flexion contractions (LME group); and the fourth (control) group will not be trained will participate in the strength tests. We expect that the strength improvement after training will be: MVC group > HME group > LME group = control group. We also expect that the strength increase in the MVC and HME groups will result in an improvement in daily living function. Aim 2 is determine the neural mechanisms underlying muscle strength improvements. We hypothesize that an increase in the central nervous system (CNS) drive is the primary mechanism that mediates strength improvements induced by low-intensity training (HME group). To evaluate the CNS drive, four measurements will be made using the same subjects and groups as in Ami 1: brain activation level examined by functional MRI (fMRI) and EEG-derived motor activity-related cortical potential (MRCP), surface EMG signals, and the MRI T2 relaxation time obtained from the trained muscles. We expect to find that after training: (1) the brain activation level (fMRI and MRCP), EMG, and MRI T2 will significantly increase in the MVC and HME groups; and (2) the amplitude of increases in these measurements will be: MVC group = HME group > LME group = control group. The knowledge gained from these studies will substantially advance the current understanding of mechanisms underlying human voluntary muscle strengthening and will have direct application in neuromuscular rehabilitation for older adults and individuals who are physically handicapped and unable to perform repeated, forceful muscle contractions.

众所周知，为了加强肌肉，应该进行涉及重负荷或阻力的训练。最近，我们发现，通过低阻力但强脑力的训练，可以获得大量的自愿力量增益。相比之下，那些接受同样低强度收缩训练但精神努力程度较低的人在力量上没有改善。基于这些初步发现，我们假设肌肉力量的改善主要取决于训练期间的精神努力水平，而不是训练强度（阻力）本身。高强度训练总是增加力量的原因是因为在高强度肌肉收缩期间，精神努力很高。本研究的目的一是比较不同水平的脑力训练对肌肉力量的改善效果。四组老年受试者（大于或等于65岁）将参加一项为期12周的肘屈肌训练研究。一组将接受强度接近最大自主收缩水平的训练（MVC组）;第二组将接受高脑力、低肌肉强度的屈肘收缩训练（LME组）;第四组（对照组）将不接受训练，将参加力量测试。我们预期训练后的力量改善将为：MVC组> HME组> LME组=对照组。我们还预计，MVC和HME组的强度增加将导致日常生活功能的改善。目的2是确定肌肉力量改善的神经机制。我们假设中枢神经系统（CNS）驱动力的增加是介导低强度训练（HME组）引起的力量改善的主要机制。为了评价CNS驱动，将使用与Ami 1相同的受试者和组进行四次测量：通过功能性MRI（fMRI）和EEG衍生的运动活动相关皮层电位（MRCP）检查的脑激活水平、表面EMG信号和从训练肌肉获得的MRI T2弛豫时间。我们期望在训练后发现：（1）脑激活水平（fMRI和MRCP），EMG和MRI T2在MVC和HME组中显著增加;（2）这些测量的增加幅度为：MVC组= HME组> LME组=对照组。从这些研究中获得的知识将大大推进目前对人类自愿肌肉强化机制的理解，并将直接应用于老年人和身体残疾且无法进行重复有力肌肉收缩的个人的神经肌肉康复。