Effects of wrist position and contraction on Wrist Flexors H-reflex, and its functional implications

CMUR > College of Health Care > Department of Physical Therapy, Graduate Institute of Rehabilitation Science > Journal articles > Item 310903500/1618

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Title:	Effects of wrist position and contraction on Wrist Flexors H-reflex, and its functional implications
Authors:	陳芬芬(Fen-Fen Chen);陳芬芬(Fen-Fen Chen);羅瑞寬(Sui-Foon Lo);孟乃欣(Nai-Hsin Meng);林千琳(Chien-Lin Lin);周立偉(Li-Wei Chou)
Contributors:	健康照護學院物理治療學系
Keywords:	Wrist flexors;Isometric contraction;Wrist position;H-reflex
Date:	2006
Issue Date:	2009-08-19 17:04:07 (UTC+8)
Abstract:	In order to determine whether joint position exerts a powerful influence on length-tension regulation in multiarticulate wrist flexors, three wrist positions (neutral, flexion and extension) and four levels of flexor contraction [0%, 10%, 20% and 30% maximum voluntary contraction (MVC)] were manipulated. There were significant differences in H-reflex amplitudes according to wrist positions and levels of flexor contraction. H-reflex increased linearly as a function of contraction in all three wrist positions. H-reflex was consistently larger in the wrist flexion than in the wrist extension position. The strength of the relationship (omega2) indicated that wrist position had a greater effect on H-reflex than force of muscle contraction. The interaction between wrist flexors contraction and joint position was significant only in the wrist flexion position. Trend analysis showed that, in the wrist flexion position, a low level of contraction was sufficient to maximally facilitate the H-reflex; however, a quadratic component was seen at higher contraction levels. The above findings may reflect the length-tension relationship of the multiarticulate wrist flexors. Therefore, this paper will discuss the functional implications related to the larger H-reflex in flexion position and the depressed H-reflex in the wrist extension position.
Relation:	JOURNAL OF ELECTROMYOGRAPHY AND KINESIOLOGY16(16):440~447
Appears in Collections:	[Department of Physical Therapy, Graduate Institute of Rehabilitation Science] Journal articles

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