Publication:

踝關節功能性不穩定對於排球攔網動作時下肢肌電訊號的影響

排球運動在攔動動作中踝關節傷害有很高的發生比例(63-90 %)，其中球員二次扭傷機率高達79%，這表示在初次扭傷後踝關節的受傷風險大幅提高。過去許多研究認為扭傷後形成的踝關節功能性不穩定是造成反覆扭傷的主因。而過去文獻較少對踝關節功能性不穩定球員在攔網的動作進行研究，此外，研究大多探討功能性不穩定對傷側腳踝的影響，缺少實際動作時下肢整體神經肌肉功能影響的探討。目的：藉由觀察踝關節功能性不穩定之不穩定組球員與健康之控制組球員在攔網起跳和著地時肌電訊號的差異，找出可能導致不穩定組球員再度扭傷的原因。方法：在模擬球場進行過網與不過網攔網動作，以肌電訊號系統搭配測力板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、肌肉活化時間點、肌肉共同收縮比值上的差異。結果：a )肌電活化程度上，過網攔網的著地前與著地後兩組的差異只出現在踝部肌肉，而不過網攔網時的差異主要出現在膝部肌肉。b ) 肌電活化時間上，不過網攔網起跳時，不穩定組踝部肌肉較早活化；在兩種攔網動作的著地時期，活化時間的主要差異上，控制組皆早於不穩定組。c ) 肌肉徵召模式上，著地時兩組在遠、近端肌肉使用模式不相同。在動作策略上，兩種攔網動作時，不穩定組受試者之間在起跳與著地時採用相似的策略。d ) 共同收縮比值上，兩種攔網動作的著地前與著地後，兩組主要差異在股直肌/股二頭肌；踝部共同比值的差異只出現在過網攔網的著地前。結論：踝關節功能性不穩定球員在進行攔網動作時，起跳時的各參數與控制組較為相似，而主要差異發生在著地時，表示肌肉功能對於不穩定組在著地時進行緩衝與穩定的控制是相當重要的。不穩定組動作策略上的選擇單一，可能不利於攔網著地時突發狀況的反應。兩組的差異不只在踝部肌肉也出現在膝部，表示踝關節功能性不穩定的影響不只侷限於踝關節，在治療與復健上應以整體下肢的功能回復為考量。

Ankle injuries is common in the volleyball blocking (63~90 %). Athletes with ankle injuries would have a significant risk for suffering the secondary injury (79%). Based on the previous studies, ankle functional ankle instability is quite frequent following an ankle sprain. There have been several laboratory researches focused on the influence of functional instability on injured ankle. However, very little studies have been conducted in investigating the effect of functional instability on the neuromuscular function of the lower limb in real sports condition. Objective: To measure the electromyography (EMG) of the lower extremity in the volleyball players with and without ankle functional instability during the blocking movement and attempt to understand the mechanism of ankle injury. Methods: We used EMG system and force plate to measure the EMG signal of lower extremity during the cross net blocking (CB) and non-cross net blocking (NCB) movements under simulated environment. For the statistical analysis, independent t test was preformed to compare the EMG muscular activities between control group (CG) and instability group (IG). Results: a) For the amplitude of muscular activity in CB movement, there was a significant difference between CG and IG in the ankle muscles. Significant difference between two groups in the NCB movement was found in the knee muscles. b) In the jumping phase of NCB movement, the onset timing of EMG activity was earlier in the IG than in the CG; in the landing phase, the onset timing was earlier in the CG than in the IG during CB and NCB movements. c) For the muscle recruitment pattern, both groups showed different muscle activation patterns. d) For the co-contraction ratios, in the pre-landing and post-landing phases, the significant difference between two groups was found in rectus femoris/biceps femoris. Conclusions: The main differences between CG and IG were found in the landing phase of volleyball blocking. Our data suggested that the abilities of the shock absorption and the motor control in the landing of volleyball blocking were important for the IG group. Less variation of movement strategy in IG might lead to reduce the reactive ability especially in the unexpectedly landing situation. The differences between IG and CG were found not only on ankle muscles but also knee muscles, indicating that FAI may influence multiples joints of the lower limb. The overall muscle functions in the lower limb should be taken into consideration for the FAI patients in the injury treatment and rehabilitation.