增強式訓練對腓腸肌神經肌肉及機械特性之影響

Abstract

前言：增強式運動常加入運動員訓練中，目的為加強爆發力，這是由於在需要大量及快速力量的運動中，爆發力對運動員的勝負佔很大的關鍵。過去相信此訓練與運動神經調控與肌肉肌腱能量運用有關。增強式運動的本質為一個快速且力量大的動作，過程包含了(一)、參與肌肉收縮前的伸展或以反向動作來激發(二)、伸展 – 收縮循環，其主要目的是將神經系統的興奮性提高，來增加神經肌肉系統的反應能力，但至今仍無具體研究證實其機制。而過去的學者認為，增強式運動訓練的效果僅在於神經適應方面，對於肌肉型態學的改變（如肌肉截面積等），並沒有產生任何改變。 近年來由於超音波影像的發展，使得我們可以在人體上經由等長收縮的方式，並且藉由超音波影像，測得過去只能從離體實驗 (in vitro) 才能得到的肌肉以及肌腱等複合體的黏彈特性，因此更能反應出肌肉肌腱複合體在人體中真實的表現，以及訓練後之變化。此外，本實驗也利用神經電刺激的方式，評估肌肉活化程度，以及神經傳導測試週邊神經特性，探討在整個運動訓練後，腓腸肌肌肉因為中樞以及週邊神經的改變而造成活化程度的改變。 因此，本實驗藉由超音波影像學，以及表面神經傳導和肌電圖訊號來去對增強式訓練做一個完整的評估與探討，以提供在運動訓練方面，依此方式得以評估神經以及肌肉特性，並依此作為訓練依據，得以達到最佳的運動表現。 目的：討論8週的增強式運動訓練對健康年輕人小腿腓腸肌肌肉活性及機械特性之影響。材料與方法：16位下肢在六個月內沒有因為受傷而接受任何醫療協助的，接受８週增強式訓練前後，接受使用神經傳導檢查，表面肌電圖，等長肌力測力儀，電子量角器以及高頻影像超音波等工具之量測，以了解肌肉活性改變包括(1)肌肉適應情形(2)神經元的改變(3)神經傳導速率的變化以及肌肉肌腱複合體的機械特性，包括肌肉(1)肌束長度(2)肌束與深層腱鞘的角度(3)肌束彎曲度(4)肌肉組成，以及肌腱腱鞘複合體的 (1) 剛性與 (2)遲滯現象以及機電傳導延遲時間。結果：第四週時神經適應改變已達顯著，並且反應在肌肉活化程度（+13%, p<0.0083）以及比目魚肌標準化肌電訊號方均跟值（+56%, p<0.0083）上，最大自主用力同時伴隨著增加（+9%, p<0.0083）。八週訓練結束後，肌腱腱鞘複合體之剛性變大（+48%, p<0.0083），跳高增加量也在八週訓練結束後達顯著差異。然而在肌肉本身的結構以及組成上面，經由增強式訓練後，並沒有顯著的變化。結論：八週的增強式訓練藉由神經適應以及肌腱腱鞘複合體剛性的改變，提昇最大自主用力以及增進跳高高度的表現。

Introduction：Plyometric exercise training has been used to train athlete for developing a explosive force. This explosive force is the key point of the competition in exercise requiring large power. It is believed that plyometric exercise training may affect neural adaptation and the usage of energy in tendon. Plyometric exercise is defined as a fast and powerful movement using a active eccentric contraction induce a powerful concentric contraction (stretch-shortening cycle(SSC)). Purpose of plyometric exercise is to increase the level of excitation of neural system to improve the ability of reaction action of neuromuscular system, but the mechanism is not well understood. Previous study suggested that the effects of plyometric exercise training dominant in neural adaptation rather than the structure or morphology (ex: cross-section area) change in the muscle. Due to the development of ultrasonography, we could detect the viscoelastic properties in vivo in muscle-tendon complex by isometric contraction. By these techniques, we could understand the actual characteristics in human being and the change after training. In the other way, we use twitch interpolation technique to detect the change of muscle activation. Accordingly, the study is to completely detect the effect of plyometric exercise training by ultrasonography, nerve conduction velocity and electromyography. The results could be an information for assessing the characteristics of neuron and muscle and a principle for training to achieve the maximum exercise performance. Purpose：To detect the effects on muscle activation level and mechanical properties of human gastrocnemius muscle of eight weeks plyometric exercise training. Methods and Materials：Sixteen healthy young college students without requiring medical service for lower limb due to injury in past 6 months accept 8 weeks plyometric exercise training. Using nerve conduction velocity test, surface electromyography, isometric dynamometer, electrogoniometer and ultrasonography to detect the change of (1)muscle activation level. (2)number of α-motorneuron. (3)nerve conduction velocity. And the mechanical properties of muscle-tendon complex are including (1)fascicle length. (2)fascicle angle. (3)fascicle curvature in muscle(4)muscle composition and (1)stiffness (2)hysterisis in tendon and electromechanical delay are also analysis. Result：In 4 weeks, there is a significantly increased in neural adaptation reflected in muscle activation（+13%, p<0.0083） and RMS-EMG /Mmax（+56%, p<0.0083） of soleus muscle. The isometric maximal voluntary contraction also increased（+9%, p<0.0083）significantly. After 8 weeks training, there is significantly increased in stiffness of tendon-aponeurosis complex（+48%, p<0.0083） and the jumping performance. However, there is no significant change in muscle architecture and composition after 8 weeks plyometric exercise training. Conclusion： The effects of 8 weeks plyometric exercise training may increase isometric maximal voluntary contraction and jumping performance by the neural adaptation and the mechanical property of tendon-aponeurosis complex.