Physical Therapy Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, United States.
Arch Gerontol Geriatr. 2013 Jan-Feb;56(1):279-84. doi: 10.1016/j.archger.2012.06.017. Epub 2012 Aug 27.
Age-related declines in neuromuscular function are well-documented, though the mechanisms underlying these deficits are unclear. Specific changes in corticospinal and intracortical neurophysiology may contribute, but have not been well studied, especially in lower extremity muscles. Furthermore, variations in physical activity levels may potentially confound the interpretation of neurophysiologic findings. Therefore, the purpose of this study was to quantify differences in transcranial magnetic stimulation (TMS) measures of corticospinal and intracortical excitability of the quadriceps between healthy, active older and younger adults. Twenty younger (age: 25.2 ± 2.4 years; body mass index [BMI]: 22.1 ± 3.0 kg/m(2); 11 males and 9 females) and twenty older (age: 67.7 ± 5.5 years; BMI: 26.8 ± 3.8 kg/m(2); 11 males and 9 females) subjects who exercised regularly (at least 30 min, 3 times/week) completed testing. Motor evoked potentials (MEPs) were measured by superficial electromyographic recordings of the vastus lateralis (VL). Measures of corticospinal excitability using a double cone TMS coil included resting motor thresholds (RMT), resting recruitment curves (RRCs) and silent periods (SP). Intracortical excitability was measured using paired pulse paradigms for short interval intracortical inhibition (SICI) and intracortical facilitation (ICF). No statistically significant differences between older and younger adults were found for RMT, RRC slopes, SP, SICI or ICF measures (p>0.05). The physically active nature of the older adults included in this study may have contributed to the lack of differences in corticospinal and intracortical excitability since physical activity in older adults attenuates age-related declines in neuromuscular function.
年龄相关的神经肌肉功能下降是有据可查的，尽管这些缺陷的机制尚不清楚。皮质脊髓和皮质内神经生理学的特定变化可能会有所贡献，但尚未得到很好的研究，特别是在下肢肌肉中。此外，身体活动水平的差异可能会混淆对神经生理发现的解释。因此，本研究的目的是定量比较健康、活跃的老年和年轻成年人股四头肌的经颅磁刺激（TMS）皮质脊髓和皮质内兴奋性测量值的差异。20 名年轻成年人（年龄：25.2 ± 2.4 岁；体重指数 [BMI]：22.1 ± 3.0 kg/m(2)；11 名男性和 9 名女性）和 20 名年龄较大的成年人（年龄：67.7 ± 5.5 岁；BMI：26.8 ± 3.8 kg/m(2)；11 名男性和 9 名女性）经常进行锻炼（至少 30 分钟，每周 3 次）完成测试。通过外侧股四头肌的表面肌电图记录测量运动诱发电位（MEP）。使用双锥 TMS 线圈测量皮质脊髓兴奋性的指标包括静息运动阈值（RMT）、静息募集曲线（RRC）和静息期（SP）。使用短间隔皮质内抑制（SICI）和皮质内易化（ICF）的成对脉冲范式测量皮质内兴奋性。在 RMT、RRC 斜率、SP、SICI 或 ICF 测量值方面，老年组和年轻组之间没有统计学上的显著差异（p>0.05）。本研究中包括的活跃的老年成年人的身体活动性质可能导致皮质脊髓和皮质内兴奋性没有差异，因为老年成年人的身体活动减轻了与年龄相关的神经肌肉功能下降。
