使用超音波影像評估不同靜態伸展技術對腓腸肌肌肉肌腱複合體延展性之變化

Abstract

腓腸肌之肌肉肌腱複合體包括肌肉、腱膜、肌腱三大部分，如有足夠的柔軟度則可協助完成大部分日常活動或運動的動作而不至於產生傷害，亦可儲存或釋放彈性位能來提供動作時的能量轉移，因此維持適當的柔軟度是很重要的。早期許多研究指出靜態伸展技術不僅可增加關節角度，尚可降低外力牽拉時的被動阻力。近年來開始有學者利用超音波影像直接測量腓腸肌在靜態伸展前後的變化。然而這類論文多半受限於探頭尺寸，無法區分肌肉或腱膜長度的變化；且所採用的技術是膝伸直的靜態伸展技術，從未有實驗探討臨床上常用的膝微彎時的靜態伸展。因此，本研究藉由全景超音波影像系統測量腓腸肌之肌肉與腱膜的延展性，旨在探討兩種不同膝關節角度的靜態伸展技術對於腓腸肌各部份延展性的變化，用以更深入瞭解不同的伸展技術對組織延展性的影響。 本研究屬於前瞻性、隨機順序、單盲，以及前後測的實驗設計，招募15名健康且保持運動習慣的年輕人進行實驗。受試者皆以隨機順序執行膝伸直與膝微彎等兩種靜態伸展技術，兩種技術施行時間相隔一星期。量測項目包括以電子量角器測量踝關節的最大背屈角度、以全景超音波影像分別測量腓腸肌的肌肉與腱膜長度、以等速肌力儀測量踝蹠屈肌的被動阻力，並以自製的跳高板測量垂直跳高度，所有變項皆在介入前、後各測量一次。上述各參數的兩次前測結果，用來進行信度的考驗。另外，全景超音波系統測量距離的效度，是以自製的樣本進行驗證。所有統計分析皆在SPSS 16th套裝軟體進行，以重複量測變異數分析計算介入前後以及兩種介入間的變化，並以組內相關係數與量測標準誤計算各個參數的測試者內信度。效度部分則使用皮爾森相關係數與量測誤差進行分析。顯著水準訂在α= 0.05，而檢定力則訂在 0.8。 本研究主要結果為：(一) 使用全景超音波影像系統測量組織長度具有良好的信度與效度；(二) 施行膝伸直靜態伸展技術較能增加肌肉部份的延展性，而膝微彎技術較能增加腱膜部份的延展性；(三) 兩種技術皆能增加踝背屈角度，但二者間沒有顯著差異；(四) 兩種技術皆無法改變踝蹠屈肌的被動阻力；(五) 施行膝伸直技術後垂直跳高度會顯著地下降，但膝微彎技術後垂直跳高度不變。 本研究為世界首度使用全景超音波影像觀察不同的伸展技術對組織延展性的變化，也是第一篇探討膝微彎靜態伸展技術的研究。由於腓腸肌是一個不同材料的複合體，本研究發現兩種靜態伸展技術雖都能改善組織的延展性，但延展的組織部份卻有所不同。未來在進行肌肉組織伸展時，必須先區辨欲伸展的組織部分，來決定所執行的靜態伸展技術，如此方能解決問題，且不會對運動表現產生負面影響。全景超音波影像可觀察肌肉細部的變化，因此未來研究可藉此觀察各種動、靜態伸展技術之適用性與參數變化，包含使用時機、使用強度、持續時間，以及合適的運動種類等。更可藉此觀察各類動作或施行其他治療技術後肌肉組織細微的變化，以更深入瞭解肌肉的功能。

The gastrocnemius muscle-tendon unit (MTU) consists of three portions of tissue structures, including the muscle, the aponeurosis, and the free tendon. Sufficient flexibility of the MTU is required to accomplish most daily or sports activities and to prevent from injuries. Furthermore, the tissue extensibility accounts for most part of the internal energy during human movements through storing and releasing the elastic energy. Thus, to employ an effective flexibility exercise was indispensable for the MTU of the gastrocnemius muscle. The widely-used static stretching technique has been noted as an effective method to increase the angle of the ankle dorsiflexion and decrease the passive tension of the plantarflexor during passive stretch. With the advance in imaging techniques, the change in the MTU after the static stretching technique could be measured directly using the real-time ultrasonography. However, to further distinguish changes in the muscle portion from that in the aponeurosis portion is subject to the size of the probe that creates a limited ultrasonographic field-of-view. Besides, only the static stretching technique with the knee in the fully extended position (SS-ext) has been examined. There is no study to investigate the one with the knee in the slightly flexed position (SS-flex) which was also used frequently. Therefore, the purpose of this research was to investigate the tissue extensibility of the gastrocnemius muscle after both static stretching techniques using the panoramic ultrasonography. The research was a prospective, randomized-order, single-blinded, and pretest/posttest design. There were 15 healthy and recreationally active adults recruited for the research. All participants received two static stretching techniques at a 1-week interval and the intervention order was employed randomly. The measurements included maximum ankle dorsiflexion angle measured by an electrogoniometer, length of the muscle and the aponeurosis portion of the gastrocnemius measured by the panoramic ultrasonographic system, passive tension of the ankle plantar flexor measured by the isokinetic system, and countermovement jump height evaluated by a customized jump height measuring board. All variables were tested before and after the intervention in both sessions. A 2×2 ANOVA with repeated measures was used to compare the differences between conditions, between different testing sessions, and their interaction. The data of each measurement tested before the intervention in the first two sessions were used to analyze the reliability of these measurements. The intra-class correlation coefficient and standard error of measurement were used to test the intrarater reliability of measurements on different days. The validity of the panoramic ultrasonography for the length measurement was tested using a customized phantom, and analyzed using the Pearson's correlation coefficient and the measurement error. All statistical analyses were executed using SPSS 16th. The significant level was set at α=.05 while the power was 0.8. The results of the present research were: 1) The validity and the intrarater reliability of the panoramic ultrasonography were excellent for length measurement; 2) The SS-ext significantly increased the length of the muscle portion while the SS-flex significantly extended that of the aponeurosis portion; 3) Both static stretching techniques significantly improved the maximum ankle dorsiflexion angle, but no significant difference was found between two conditions; 4) Both static stretching techniques did not change the passive tension of the ankle plantar flexor during passive stretch; 5) The countermovement jump height decreased significantly for the SS-ext condition, but not for the SS-flex one. This was the first research that examined the effect of different stretching techniques on the tissue extensibility using panoramic ultrasonography and also the first research that explore the static stretch technique with the knee in the flexed position. The break-through results suggested that both static stretching techniques improve the flexibility but act on different portion of the tissue. In order to improve the flexibility effectively and avoid the detrimental effects, it was necessary to distinguish of the target tissue to be stretched before the flexibility exercise is given. Since the panoramic ultrasonography can provide more direct measures to investigate the change in the different portions within the MTU, the optimal application of two static stretching techniques, including timing, intensity, duration, and types of sports can be further examined in detail through this technology in the future. Furthermore, the effect different motions or physical therapy skills on the different portions of the muscle can also be evaluated through the panoramic ultrasonography.