The motor repertoire of older adult fallers may constrain their response to balance perturbations
The motor repertoire of older adult fallers may constrain their response to balance perturbations
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DOI：
10.1152/jn.00302.2018
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发表时间：
2018-11-01
影响因子：
2.5
通讯作者：
Franz, Jason R.
中科院分区：
文献类型：
--
作者：
Allen, Jessica L.;Franz, Jason R.
老年人摔倒的风险很高。大多数跌倒发生在行走等运动活动中。这项研究旨在提高我们对神经肌肉控制变化与老年人行走过程中动态平衡挑战时跌倒风险增加相关的理解。运动模块（也称为肌肉协同）分析确定了在行走过程中腿部肌肉的神经肌肉招募的变化，这些变化是在有或没有干扰的情况下设计的，以引起视觉上的侧向不稳定。在正常行走时，我们发现跌倒史（而不是年龄）与运动模块复杂性降低有关，而年龄（而不是跌倒史）与模块恢复时间的逐级变化增加有关。此外，在存在光流扰动的情况下，电机模块的复杂性没有改变。跌倒史对腿部肌肉恢复的具体影响包括缺乏和/或无法独立恢复运动模块，这些运动模块通常用于执行对行走平衡控制重要的生物力学功能。这些结果表明，即使在存在扰动的情况下，跌倒者也没有招募适当的运动模块来协调行走平衡控制。老年跌倒者行走平衡模块控制的已确定变化可能代表神经缺陷导致平衡控制不良或先前跌倒史导致代偿性运动适应。无论哪种情况，我们的研究都提供了初步证据，表明老年跌倒者的运动功能减少可能会限制他们在行走过程中适当应对平衡挑战的能力。新的和值得注意的是，这是第一个证明有跌倒史但没有明显神经功能缺陷的老年人行走时运动功能减少的研究。此外，通过在行走过程中使用虚拟现实技术来诱导侧位不稳定性的视觉感知，我们提供了初步证据，表明老年跌倒者的运动功能减少可能会限制他们在行走过程中适当应对平衡挑战的能力。
Older adults are at a high risk of falls. and most falls occur during locomotor activities like walking. This study aimed to improve our understanding of changes in neuromuscular control associated with increased risk of falls in older adults in the presence of dynamic balance challenges during walking. Motor module (also known as muscle synergy) analyses identified changes in the neuromuscular recruitment of leg muscles during walking with and without perturbations designed to elicit the visual perception of lateral instability. During normal walking we found that a history of falls (but not age) was associated with reduced motor module complexity and that age (but not a history of falls) was associated with increased step-to-step variability of module recruitment timing. Furthermore, motor module complexity was unaltered in the presence of optical flow perturbations. The specific effects of a history of falls on leg muscle recruitment included an absence and/or inability to independently recruit motor modules normally recruited to perform biomechanical functions important for walking balance control. These results suggest that fallers do not recruit the appropriate motor modules necessary for well-coordinated walking balance control even in the presence of perturbations. The identified changes in the modular control of walking balance in older fallers may either represent a neural deficit that leads to poor balance control or a prior history of falls that results in a compensatory motor adaptation. In either case, our study provides initial evidence that a reduced motor repertoire in older adult fallers may be a constraint on their ability to appropriately respond to balance challenges during walking.NEW & NOTEWORTHY This is the first study to demonstrate a reduced motor repertoire during walking in older adults with a history of falls but without any overt neurological deficits. Furthermore, using virtual reality during walking to elicit the visual perception of lateral instability, we provide initial evidence that a reduced motor repertoire in older adult fallers may be a constraint on their ability to appropriately respond to balance challenges during walking.