School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Floor 3, No.17, Xuzhou Rd., Zhongzheng District, Taipei City, 100, Taiwan, ROC.
Department of Physical Therapy and Assistive Technology, National Yang-Ming University, No.155, Sec.2, Linong Street, Taipei, 112, Taiwan, ROC.
Phys Ther Sport. 2019 May;37:27-33. doi: 10.1016/j.ptsp.2019.02.004. Epub 2019 Feb 19.
Morphological changes of the abductor hallucis muscle (AbH) in flexible flatfoot (FF) individuals influence regulations of the medial longitudinal arch (MLA). Prolonged and repeated stretching of AbH in flexible flatfoot may cause changes in muscle reflex properties and further influence postural performance. However, AbH muscle reflex under different postural conditions have never been examined. The purpose of this study was to investigate differences in AbH H-reflex and postural performance between individuals with normal foot (NF) alignment and FF under prone, double-leg stance (DLS), and single-leg stance (SLS) conditions.
Cross-sectional study.
University laboratory.
Individuals with FF (n = 12) and NF (n = 12).
AbH H-reflex, AbH EMG and center of pressure (CoP) displacement.
Under all postural conditions, AbH H-reflex was significantly lower in the FF group (P < .05). Under the SLS condition, AbH EMG was significantly higher in the FF group (P < .05), and CoP displacement for the medial-lateral and anterior-posterior directions were significantly higher in the FF group (P < .05).
With increased postural demand, FF individuals maintained their postural stability by recruiting greater AbH activities than through automatic stretch reflex, but FF individuals still showed inferior posture stability.
足弓塌陷（FF）人群中拇展肌（AbH）的形态变化会影响内侧纵弓（MLA）的调节。FF 人群中 AbH 的长期反复拉伸可能导致肌肉反射特性发生变化，进而影响姿势表现。然而，在不同姿势条件下，AbH 肌肉反射尚未被检测到。本研究的目的是探究在俯卧位、双腿站立（DLS）和单腿站立（SLS）三种姿势条件下，NF 组和 FF 组的 AbH H 反射和姿势表现是否存在差异。
横断面研究。
大学实验室。
FF 组（n=12）和 NF 组（n=12）。
AbH H 反射、AbH 肌电图和中心压力（CoP）位移。
在所有姿势条件下，FF 组的 AbH H 反射均显著降低（P<.05）。在 SLS 条件下，FF 组的 AbH EMG 显著升高（P<.05），且内侧-外侧和前-后方向的 CoP 位移显著升高（P<.05）。
随着姿势需求的增加，FF 人群通过募集更大的 AbH 活动来维持其姿势稳定性，而不是通过自动拉伸反射，但 FF 人群的姿势稳定性仍较差。
