McGregor Keith M, Crosson Bruce, Mammino Kevin, Omar Javier, García Paul S, Nocera Joe R
VA Rehabilitation R&D Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Medical Center, Decatur, GA, United States.
Department of Neurology, Emory University School of Medicine, Atlanta, GA, United States.
Front Aging Neurosci. 2018 Jan 4;9:422. doi: 10.3389/fnagi.2017.00422. eCollection 2017.
Data from previous cross-sectional studies have shown that an increased level of physical fitness is associated with improved motor dexterity across the lifespan. In addition, physical fitness is positively associated with increased laterality of cortical function during unimanual tasks; indicating that sedentary aging is associated with a loss of interhemispheric inhibition affecting motor performance. The present study employed exercise interventions in previously sedentary older adults to compare motor dexterity and measure of interhemispheric inhibition using transcranial magnetic stimulation (TMS) after the interventions. Twenty-one community-dwelling, reportedly sedentary older adults were recruited, randomized and enrolled to a 12-week aerobic exercise group or a 12-week non-aerobic exercise balance condition. The aerobic condition was comprised of an interval-based cycling "spin" activity, while the non-aerobic "balance" exercise condition involved balance and stretching activities. Participants completed upper extremity dexterity batteries and estimates of VOmax in addition to undergoing single (ipsilateral silent period-iSP) and paired-pulse interhemispheric inhibition (ppIHI) in separate assessment sessions before and after study interventions. After each intervention during which heart rate was continuously recorded to measure exertion level (load), participants crossed over into the alternate arm of the study for an additional 12-week intervention period in an AB/BA design with no washout period. After the interventions, regardless of intervention order, participants in the aerobic spin condition showed higher estimated VOmax levels after the 12-week intervention as compared to estimated VOmax in the non-aerobic balance intervention. After controlling for carryover effects due to the study design, participants in the spin condition showed longer iSP duration than the balance condition. Heart rate load was more strongly correlated with silent period duration after the Spin condition than estimated VO. Aging-related changes in cortical inhibition may be influenced by 12-week physical activity interventions when assessed with the iSP. Although inhibitory signaling is mediates both ppIHI and iSP measures each TMS modality likely employs distinct inhibitory networks, potentially differentially affected by aging. Changes in inhibitory function after physical activity interventions may be associated with improved dexterity and motor control at least as evidence from this feasibility study show.
以往横断面研究的数据表明，在整个生命周期中，身体素质的提高与运动灵活性的改善相关。此外，身体素质与单手动任务期间皮质功能的偏侧化增加呈正相关；这表明久坐不动的衰老与影响运动表现的半球间抑制丧失有关。本研究对先前久坐不动的老年人进行运动干预，以比较运动灵活性，并在干预后使用经颅磁刺激（TMS）测量半球间抑制。招募了21名居住在社区、据报道久坐不动的老年人，将他们随机分组并纳入为期12周的有氧运动组或为期12周的非有氧运动平衡组。有氧运动组包括基于间歇的骑行“动感单车”活动，而非有氧运动“平衡”运动组则包括平衡和伸展活动。参与者除了在研究干预前后的单独评估环节中接受单次（同侧静息期-iSP）和配对脉冲半球间抑制（ppIHI）外，还完成了上肢灵活性测试和最大摄氧量评估。在每次干预期间持续记录心率以测量运动强度（负荷），参与者按照AB/BA设计交叉进入研究的另一组，进行额外的12周干预期，且无洗脱期。干预后，无论干预顺序如何，与非有氧运动平衡干预后的估计最大摄氧量相比，有氧运动动感单车组的参与者在12周干预后的估计最大摄氧量水平更高。在控制了由于研究设计导致的遗留效应后，动感单车组的参与者显示出比平衡组更长的iSP持续时间。与估计的最大摄氧量相比，动感单车组后的心率负荷与静息期持续时间的相关性更强。当用iSP评估时，12周的体育活动干预可能会影响与衰老相关的皮质抑制变化。尽管抑制信号介导了ppIHI和iSP测量，但每种TMS模式可能采用不同的抑制网络，可能受到衰老的不同影响。至少从这项可行性研究的证据来看，体育活动干预后抑制功能的变化可能与灵活性和运动控制的改善有关。
