背景與目的：前人的研究中指出異常的足部姿勢與跟高都會影響行走時的足部功能。此外，也有研究提出下肢傷害與異常足部姿勢以及跟高具有相關性。臨床上常見的扁平足者行走時足部與踝關節的外翻會明顯多於正常足者，而高弓足者則有較多的足踝內翻。另一方面，跟高提升的情況下，也有學者發現其會使下肢的矢狀面有明顯的姿勢改變，如足部與踝關節蹠屈、膝關節屈曲。由於關節耦合動作，當足部與踝關節擺在蹠屈姿勢也會合併內翻動作出現。不僅如此，包含膝與髖關節的橫切面活動也會受到影響，例如外轉動作增加。然而，目前尚未有研究針對不同足部姿勢的人穿上不同跟高鞋子對於行走時的步態之交互影響進行討論。研究者想知道的是，是否有較大外翻的扁平足及較大內翻的高弓足者穿上有跟高的鞋子之後會有不一樣的下肢動作與肌肉活性。因此本研究的目的乃在探討足部姿勢與跟高對於行走時下肢動作及肌電圖的交互影響。

方法：本研究收錄47名健康女性，包括扁平足組17名（平均年紀21.4歲），正常足弓組15名（平均年紀24.7歲），高弓足組10名（平均年紀24.1歲）。分組依據是根據足部姿勢指數的分數而定。每位受試者皆要隨機在0公分、1公分與3公分跟高下在跑步機上行走。研究者以每次10秒的時間利用動作分析攝影機和肌電圖系統紀錄五次行走的下肢動作與肌肉活性。此研究的量測參數為後足、踝、膝與髖關節的運動學參數、時間參數以及下肢肌肉活性與肌肉活化時間。本研究使用的統計方法為雙因子變異數分析重複測量，顯著水平設為P<0.05。

結果：此研究發現部分動作參數受到足部姿勢與跟高的交互影響。姿勢與跟高對後足內翻與踝內翻動作有顯著的交互作用（p值皆<.05）。進一步分析顯示，扁平足組傾向增加踝內翻，正常足組傾向減少踝內翻，而高弓足則傾向增加後足內翻以適應跟高帶來的影響（所有p值僅接近.05）。另外，高弓足組會因為高跟鞋而延遲最大膝內展時間（p=.028）。正常足組的膝最大外轉角度可能因為踝內翻動作減少而變少（p=.044）。在肌肉活性方面，跟高和姿勢則沒有對任何量測的肌肉產生明顯的交互影響。
在足部姿勢影響方面，研究者只發現扁平足組的最大髖外轉時間會明顯早於另外兩組，而最大髖內轉時間則晚於正常足組（p皆<.05），肌肉活性參數也只有扁平足組與高弓足組的脛前肌在接觸期的最大活性會大於正常足組（p=.008）。其餘參數並沒有發現足部姿勢的明顯影響。
在跟高影響方面，跟高明顯影響了許多運動學參數。踝關節蹠屈的動作會隨跟高增加而變大，相對地背屈動作則減少（p皆<.05）。膝關節矢狀面的屈曲角度也會隨跟高增加而變大（p<.001），內轉與外轉的角度雖然在3公分跟高下沒有明顯改變，但1公分跟高的內-外轉活動度會大於0公分跟高（p=.036）。3公分跟高雖然使髖關節矢狀面的活動度大於0公分跟高（p=.019），但屈曲與伸直動作並沒有因跟高而改變。跟高也同樣影響了下肢肌肉活性，脛前肌與股二頭肌在接觸期的活性隨跟高提升而明顯增加（p皆<.05）。脛前肌、腓骨長肌及腓腸肌則在站立中/推進期的活性隨跟高提升而增加（p皆<.05）。股直肌的活性雖然沒有發現明顯差異，但站立中/推進期時的活化時間會受跟高提升而較早達到最大活性（p=.034）。

結論：這項研究顯示後足、踝關節與膝關節的運動會受到足部姿勢與跟高的交互影響，尤其在後足與踝關節可以觀察到三組受試者會有不同的適應跟高策略。然而，足部姿勢的影響只對髖旋轉時間以及脛前肌活性有明顯的改變。而在跟高方面，其對踝關節、膝關節與髖關節都有明顯影響，尤其在遠端的踝關節受跟高的影響最大。而脛前肌、腓骨長肌、腓腸肌及股二頭肌同樣因為跟高增加而活性提升。並且股直肌的活化時間也有所提早。
根據這項研究的結果，在臨床上可以建議扁平足女性穿著低跟高跟鞋，然而對高弓足女性則不適合給此建議。未來研究可以針對不同足部姿勢差異的個案，研究他們在穿著不同設計的高跟鞋下(不同跟高、底面積、材質)其運動學與力學的表現，以期更完善瞭解足部姿勢與跟高的交互影響。

The objective of this research was to explore the interaction effect of foot posture and heel height for the lower extremities motion and muscle activity during walking. There were three foot posture subjects who were asked to wear different heel height shoes and the researcher recorded lower extremities motion and muscle activity during the subjects walking. There were significant interaction effects on the rearfoot inversion angle and the ankle inversion angle. The subjects in the three groups had different reactions while they wore higher heel height shoes. The research also found that there were lots of variables of motion and muscle activity affected by the heel height effect but the foot posture effect only affected few variables of motion and muscle activity. According to the findings of the current study, clinicians could advise those women who have the planus foot to wear high heels; however, for the subject with cavus foot, they should not wear high heels in order to avoid aggravating inversion. Future studies could explore the kinematics and kinetic when subjects were wearing different designs of high heels for understanding the interaction effect between foot posture and heel height completely.

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