Watanabe Tatsunori, Saito Kotaro, Ishida Kazuto, Tanabe Shigeo, Nojima Ippei
Department of Physical Therapy, Nagoya University Graduate School of Medicine, 1-1-20 Daiko-Minami, Higashi-ku, Nagoya, Aichi, 461-8673, Japan.
Japan Society for the Promotion of Science, Tokyo, Japan.
Exp Brain Res. 2018 May;236(5):1229-1239. doi: 10.1007/s00221-018-5217-3. Epub 2018 Feb 26.
To investigate the effects of aging on coordination of plantar flexor muscles during bipedal and unipedal stances, we examined a relationship between the center of pressure sway and electromyographic activity of these muscles, and also the common neural input, using a coherence analysis. Healthy young and elderly adults were asked to perform bipedal and unipedal standing. The electromyograms were recorded unilaterally from the medial and lateral gastrocnemius (MG and LG) and soleus (SL) muscles, and the common input was analyzed for MG-LG, MG-SL, and LG-SL pairs in two frequency bands: a delta band, that is associated with force variability, and a beta band, that could reflect the corticospinal drive. Main results indicated that the MG and SL muscles worked for lateral sway, while the LG muscle worked for medial sway during the unipedal stance. The delta-band coherence for the MG-SL pair and the beta-band coherences for all the pairs were larger during the unipedal than bipedal stance for both groups. The delta-band coherence for the MG-SL pair was larger for the elderly than young adults during the unipedal stance. In addition, the beta-band coherence for the MG-SL pair was larger than the other pairs during the unipedal stance for the elderly. These findings suggest that the oscillatory activity between the MG and SL muscles is strongly involved in the control of unipedal stance, and aging would increase the cortical drive to these muscles to deal with the postural sway that could be affected by forces generated cooperatively by them.
为研究衰老对双足和单足站立时跖屈肌协调性的影响，我们使用相干分析研究了压力中心摆动与这些肌肉的肌电图活动之间的关系，以及共同神经输入。健康的年轻人和老年人被要求进行双足和单足站立。从腓肠肌内侧头和外侧头（MG和LG）以及比目鱼肌（SL）单侧记录肌电图，并在两个频段分析MG-LG、MG-SL和LG-SL对的共同输入：一个与力变异性相关的δ频段，以及一个可能反映皮质脊髓驱动的β频段。主要结果表明，在单足站立时，MG和SL肌肉用于控制侧向摆动，而LG肌肉用于控制内侧摆动。两组在单足站立时，MG-SL对的δ频段相干性以及所有对的β频段相干性均大于双足站立时。在单足站立时，老年人MG-SL对的δ频段相干性大于年轻人。此外，在单足站立时，老年人MG-SL对的β频段相干性大于其他对。这些发现表明，MG和SL肌肉之间的振荡活动强烈参与单足站立的控制，并且衰老会增加对这些肌肉的皮质驱动，以应对可能受它们协同产生的力影响的姿势摆动。
