頁籤選單縮合
題 名 | Contrast of Directional Influence upon Motor Overflow between Submaximal and Maximal Static Exertions |
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作 者 | Hwang, Ing-shiou; Lin, Chih-feng; Chen, Yi-ching; Cho, Chiung-yu; Wang, Chun-hou; | 書刊名 | 中國生理學雜誌 |
卷 期 | 49:1 民95.02 |
頁 次 | 頁22-30 |
分類號 | 398.1 |
關鍵詞 | Motor overflow; Electromyography; Isometric contraction; Task direction; |
語 文 | 英文(English) |
英文摘要 | This study investigated exertion-dependent motor overflow among healthy adults when they performed isometric tasks with contrlateral joints in different task direction. Twenty healthy adults (10 males and 10 females, mean age=26.2 yrs) were instructed to complete a set of isometric contractions of various force vectors with the shoulder, elbow, and wrist joints, in a total of ten motor tasks at submaximal and maximal intensities (50%. 100% maximal voluntary contractions). The electromyographical activates from eight muscles of the unexercised upper limb were recorded to characterize intensity of motor overflow during sustained isometric contraction. Both occurrence frequency and magnitude of motor overflow in terms of standardized net excitation (SNE) increased with exertion level for all jont movements (P<0.001). Additionally, the motor overflow magnitude depended strongly on the task direction of maximal isometric contraction (P<0.04). Motor overflow was particularly augmented by the contralateral isometric contractions where task directions were opposed to gravity. However, such a directional effect upon SNE was not evident during sub maximal contraction (P<0.05). The difference of the net excitation between maximal and submaximal contraction (DN□ data) indicated that the pectoralis major and triceps brachia consistently exhibited a marked recruitment in reaction to change in task direction of isometric contraction. Patterned motor overflow may be physiologically relevant to topological mapping of the ipsilateral pathways and altered effectiveness of use-dependent interhemispherical connectivity. The current observations provide better insight into gain in muscle strength due to contralateral exercise. |
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