Faculty of Health Sciences, Hokkaido University, Sapporo, Japan.
Rehabilitation Center, NTT Medical Center Sapporo, Sapporo, Japan.
J Sports Sci Med. 2020 Nov 19;19(4):662-669. eCollection 2020 Dec.
The effects of foot posture on postural stability and on muscular activation pattern for postural control remain unclear. This study aimed to investigate postural stability and muscular activation onset during the transition task from double- to single-leg stance in individuals with different foot postures. Twenty-seven healthy men (age: 21.5 ± 1.5 years) were divided into 3 groups using the Foot Posture Index: neutral foot (n = 10); flatfoot (n = 8); and high-arched foot (n = 9). Center of pressure (COP) data and muscle activation onset times of the tibialis anterior, peroneus longus, gastrocnemius medialis, and soleus during the transition task with eyes closed were compared among groups using one-way analysis of variance and a post-hoc Tukey honestly significant difference test (p < 0.05) when the data were normally distributed and the Kruskal-Wallis test and a post-hoc Mann-Whitney U-test with Bonferroni correction (p < 0.0167) when the data were not normally distributed. The COP displacements in the mediolateral and anteroposterior directions and the resultant COP displacement during the first 3 s after a stability time point, as determined by sequential estimation during the single-leg stance phase, differed significantly among the three groups (p < 0.05). Post-hoc tests showed that the displacements were significantly greater in the flatfoot group than in the neutral and high-arched foot groups (p < 0.05), and the effect sizes for these results were large. No muscular activation onset times showed significant intergroup differences. Postural stability was significantly decreased only in the flatfoot group, while muscle activation onsets did not differ significantly by foot posture during the transition task. Decreased postural stability may be one mechanism underlying the link between flatfoot and risk of lower limb injury, and foot posture represents a potential confounder for measuring postural stability during the transition task.
足部姿势对姿势稳定性和姿势控制的肌肉激活模式的影响尚不清楚。本研究旨在探讨不同足部姿势个体在从双腿支撑到单腿支撑过渡任务中，姿势稳定性和肌肉激活起始时间的差异。27 名健康男性（年龄：21.5±1.5 岁）根据足弓指数分为 3 组：正常足（n=10）、扁平足（n=8）和高弓足（n=9）。采用单因素方差分析和事后 Tukey Honestly Significant Difference 检验比较闭眼状态下单腿支撑过渡任务中，各组的中心压力（COP）数据和胫骨前肌、腓骨长肌、比目鱼肌和腓肠肌的肌肉激活起始时间，当数据呈正态分布时采用方差分析和事后 Tukey Honestly Significant Difference 检验（p＜0.05），当数据呈非正态分布时采用 Kruskal-Wallis 检验和事后 Mann-Whitney U 检验和 Bonferroni 校正（p＜0.0167）。在单腿支撑阶段，通过连续估计确定的稳定性时间点后的前 3 s 内，COP 在前后方向和左右方向的位移以及COP 的合成位移在 3 组之间差异有统计学意义（p＜0.05）。事后检验显示，扁平足组的位移明显大于正常足组和高弓足组（p＜0.05），且这些结果的效应量较大。肌肉激活起始时间无显著组间差异。只有扁平足组的姿势稳定性显著降低，而在过渡任务中，足部姿势对肌肉激活起始时间没有显著影响。姿势稳定性降低可能是扁平足与下肢损伤风险之间联系的一个机制，而足部姿势是在过渡任务中测量姿势稳定性的一个潜在混杂因素。
