本研究目的為比較踝關節功能性不穩定之排球球員與健康之控制組球員，在過網攔網起跳和著地時肌電訊號的差異。受測球員在球場進行過網攔網動作，以表面肌電訊號系統收集攔網各時期下肢的肌電訊號。以獨立樣本t考驗比較兩組受試者在肌電活化程度與肌肉共同收縮比值上的差異。主要結果如下：一、肌電活化程度上，兩組的差異出現在過網攔網著地前與著地後的踝部肌肉；二、共同收縮比值上，兩組主要差異在股直肌／股二頭肌、腓腸肌／脛前肌與腓骨長肌／脛前肌。本研究結論：由實驗結果發現，踝關節功能性不穩定球員在進行過網攔網動作時，在踝部與膝部的肌肉活化程度與共同收縮比值皆有顯著差異，主要出現差異的時期為落地前，表示踝關節功能性不穩定的影響不只侷限於踝關節，亦會影響近端膝關節的肌肉收縮，在復健治療上應以整體下肢的功能回復為考量。

The purpose of this study was to compare the electromyographic (EMG) difference for volleyball players with and without ankle functional instability during cross net blocking. Surface EMG system was used to measure the EMG signal of lower extremity. Independent t test was preformed to compare the EMG activities between the control group and instability group. The results were indicated as: 1. for the EMG activation level, significant difference was found at ankle muscles in pre-landing and after-landing phase. 2. for the co-contraction ratio, the significant difference was found in rectus femoris/biceps femoris, gastrocnemius/tibialis anterior and peroneal longus/tibialis anterior. These findings suggest that most EMG differences between control and instability groups were found in the muscles of ankle and knee joints in pre-landing phase of cross net blocking. It was indicated that functional ankle instability not only influences the local joint but also influences the proximal knee muscles. The rehabilitation of total lower extremity function should be taken into consideration for the volleyball players with ankle functional instability.