京都大学 · 医学
山形桃子教授の研究室は、歩行や立ち姿勢の安定性に寄与する筋肉の協調制御、特に拮抗筋の共同活性化と下肢・体幹筋の協調的働きが運動制御に与える影響を、生体力学的・神経制御的視点から解明しています。特に、姿勢 sway の分解（ラムブリング・トゥーリング）や筋活動モード（M-modes）を用いた分析により、筋肉の協調的制御が身体中心質量の安定性にどのように寄与するかを定量的に評価しています。また、膝関節症（KOA）の進行や転倒リスクの予測に関連する筋肉の機能的役割や性差の影響についても、高精度な筋骨格モデルを用いて研究を進めています。
Figures are computed from collected data and may differ slightly.
We explored the effects of voluntary coactivation of agonist-antagonist leg and trunk muscles on stability of vertical posture. Young healthy subjects performed several tasks while standing with no additional muscle coactivation, low coactivation, and high coactivation. Postural stability was estimated using indices of postural sway and of intertrial variance in the space of muscle groups with parallel scaling of activation levels (M-modes). An increase in coactivation led to a significant incre
Our study compared the results of two methods of analysis of postural sway during human quiet standing, the rambling-trembling (<i>Rm</i>-<i>Tr</i>) decomposition and the analysis of the point of intersection of the ground reaction forces (<i>zIP</i> analysis). Young, healthy subjects were required to stand naturally and with an increased level of leg/trunk muscle co-activation under visual feedback on the magnitude of a combined index of muscle activation (muscle mode). The main findings includ
We verified that the high variance in segmental configurations that destabilize the CoM in the vertical direction was related to future falls. The variables of UCM analysis can be useful for evaluating fall risk.
The main objective of this study was to determine which muscle force reduction, among the vastus muscles (VAS), rectus femoris (RF), gluteus medius (Gmed), and gluteus maximus (Gmax) most significantly influenced the knee contact force. Ten young adults walked at a comfortable speed. The medial and lateral knee contact forces (KCF<sub>med</sub> and KCF<sub>lat</sub>) were computed by a musculoskeletal model with full-force-generating capacity and four muscle inactivation models that separately c
The current study is the first to consider sex as a biological variable into ambulatory mechanics in the development of KOA. We discovered that sex-dependent alterations in knee biomechanics is a function of the presence of KOA, indicating that KOA disease may be a driver of the sex-dependent biomechanical alterations or vice versa. Although no strong conclusion can be drawn because of the low quality of evidence, these findings provide new insight into the sex differences in ambulatory knee bio
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