The H-Reflex Changes During Wrist Flexion and Wrist Extension

為了尋找最佳的H-反射測試情況，於本研究中，我們探討是否微弱的（10%，20%最大自主收縮）手腕等長屈曲以及手腕等長伸張收縮影響撓側屈腕肌的H-反射高度。再者，亦探討於撓側屈腕肌被動拉長或被動縮短的情況下，H-反射高度是否有變化。於本研究中，我們選擇撓側屈腕肌H-反射作為觀察的對象，期望對於撓側屈腕肌以及其拮抗肌的收縮狀況，以及長度等因素對於H-反射的影響有更清楚的了解。結果顯示，於七個實驗情況（0%，10%，20%手腕等長屈曲，10%，20%手腕等長屈曲，以及中性手腕姿勢，其中0%代表撓側屈腕肌被動的拉長或縮短）H-反射高度具有統計上的差異，而M-反應則是無差別。當與中性手腕姿勢時的反應相比較時，10%，20%手腕屈曲時的反射是顯著的增加，相反的，在0%，10%，20%手腕伸張時反射是顯著的被抑制。被動手腕屈曲時的反射高度與中性手腕姿勢是沒有區別的，但H-反射於0%手腕伸張時，明顯的被抑制。此結果之可能推論：手腕屈曲對於撓側屈腕肌的運動神經元有主要的促進作用，而手腕伸張則是相反的抑制作用。當撓側屆腕肌被動的拉長時，H-反射明顯的被抑制，但當它被動的拉長時，則無效果。此研究顯示：撓側屈腕肌的H-反射高度是受到手腕動作的調節的。於手腕屈曲時H-反射加強，當手腕伸張，或被動拉長時則是被抑制。結果亦顯示，於手腕屆曲時些微的收縮（10% MVC）即足以達成最佳測試情況。此種結果可延伸應用至臨床的診斷與治療。

關鍵字

撓側屈腕肌； H-反射；手腕姿勢

並列摘要

The aim of this study was to find the optimal H-reflex testing conditions regarding the wrist position and forearm muscle contractions. We investigated the effects of weak (at 10% and 20 % of maximal voluntary contraction) isometric wrist flexion and wrist extension on the Hreflex amplitudes in flexor carpi radialis (FCR). In addition, the H-reflexes during passive wrist flexion and passive wrist extension were also evaluated and compared with that at the neutral wrist position. Thus, the factors regarding contractions and mechanical properties to the changes of FCR H-reflex could be scrutinized. The H-reflex amplitudes were significantly different in the seven experimental conditions used in this study, while M-responses were not. Compared to resting neutral wrist position, the H-reflex amplitudes were significantly larger during 10% and 20% wrist flexion. On the contrary, the H-reflex amplitudes during passive and active wrist extensions were all smaller and significantly different from those at neutral positions. However, the H-reflex amplitudes during passive wrist flexion could not be distinguished from that at neutral position. The results indicated that wrist flexion itself exerted a major excitatory input on the alpha motoneurons, while the wrist extension was the contrary. In addition, passive stretch of FCR significantly reduced the H-reflex amplitude, though the passive flexion of the wrist had no effect. This study showed that the FCR H-reflex was strongly modulated in the wrist isometric contraction; high during wrist flexion, and low during wrist extension. This may be functionally important. The results also indicated that minimal tonic contraction (10% MVC) in the wrist flexion position was sufficient to obtain the best test condition. These findings also extend the diagnostic and therapeutic utility of H-reflex testing. In order to maximize the value of reflex studies, the effects of contraction level and joint position must be taken into consideration when setting the test conditions.

並列關鍵字

flexor carpi radialis ； H-reflex ； wrist position

國際替代計量

The H-Reflex Changes During Wrist Flexion and Wrist Extension

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