Kojima Hiroshi, Sakuma Eisuke, Mabuchi Yoshio, Mizutani Jun, Horiuchi Osamu, Wada Ikuo, Horiba Mitsuya, Yamashita Yutaka, Herbert Damon C, Soji Tsuyoshi, Otsuka Takanobu
Department of Musculoskeletal Medicine, Nagoya City University Medical School, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, Aichi, Japan.
J Orthop Sci. 2008 May;13(3):233-9. doi: 10.1007/s00776-008-1211-0. Epub 2008 Jun 6.
Although exercise is believed to reduce the risk of rupture of the myotendinous junction, exercise-induced structural changes in this region have not been studied. We examined exercise-induced ultrastructural changes in the myotendinous junction of the lower legs in rats.
Ten adult male LETO rats were used. Five rats were randomly placed in the Exercise group; the remaining five were used as controls and placed in the non-Exercise group. Running exercise was performed every day for 4 weeks. The tibialis anterior and gastrocnemius muscles were then removed from both legs from each animal in the two groups. The specimens were subsequently examined by transmission electron microscopy (TEM). Numerous finger-like processes were observed at the myotendinous junction. The changes in frequency of branching of the finger-like process (the number of times one finger-like process branched) and the direction of the processes (the angle of the major axis of a finger-like process to the longitudinal direction of the muscle fiber) were studied. To evaluate the two indicators above, each 10 fingerlike process was randomly and separately selected from the tibialis anterior and gastrocnemius muscles of rats, providing 50 finger-like processes of both muscles for evaluation per group.
In terms of the frequency of branching of the fingerlike processes, the mean values obtained in the non-Exercise group were 0.04 and 0.18 times, respectively, in the tibialis anterior and gastrocnemius muscles and were 0.38 and 1.16 times, respectively, in these two muscles in the Exercise group. Regarding the direction of the finger-like processes, the values were 4.1 degrees and 3.6 degrees, respectively in the non-Exercise group and 10.4 degrees and 14.5 degrees , respectively in the Exercise group. The differences between the two animal groups were significant.
Morphological changes in the myotendinous junction occurred as an adaptation to tension increased by exercise.
尽管人们认为运动可降低肌腱结合部断裂的风险，但该区域运动引起的结构变化尚未得到研究。我们研究了运动引起的大鼠小腿肌腱结合部超微结构变化。
使用10只成年雄性LETO大鼠。5只大鼠随机放入运动组；其余5只作为对照，放入非运动组。每天进行跑步运动，持续4周。然后从两组中每只动物的双腿上取下胫前肌和腓肠肌。随后通过透射电子显微镜（TEM）检查标本。在肌腱结合部观察到许多指状突起。研究了指状突起分支频率（一个指状突起分支的次数）和突起方向（指状突起长轴与肌纤维纵向的夹角）的变化。为评估上述两个指标，从大鼠的胫前肌和腓肠肌中每组随机分别选取10个指状突起，每组共50个指状突起进行评估。
就指状突起的分支频率而言，非运动组在胫前肌和腓肠肌中的平均值分别为0.04次和\(0.18\)次，运动组在这两块肌肉中的平均值分别为\(0.38\)次和\(1.16\)次。关于指状突起的方向，非运动组的值分别为\(4.1\)度和\(3.6\)度，运动组分别为\(10.4\)度和\(14.5\)度。两组动物之间的差异具有显著性。
肌腱结合部的形态变化是对运动增加的张力的一种适应性反应。
