Sakakima Harutoshi, Yoshida Yoshihiro
School of Health Sciences, Faculty of Medicine, Kagoshima University, 8-35-1, Sakuragaoka, Kagoshima 890-8506, Japan.
J Jpn Phys Ther Assoc. 2002;5(1):13-8. doi: 10.1298/jjpta.5.13.
Denervation elicits profound alterations in the morphometry of the skeletal muscle. There is evidence that the increased mechanical load placed upon the muscle via rhythmic stretching attenuates denervation induced alterations in muscle morphology. To investigate the effect of short duration static stretching (40 min/day) for denervated and reinnervated muscle, a histochemical study was performed on the soleus muscle of the rat. Twenty-one eight-week-old female Wistar rats were used. Partial denervation was carried out by locally freezing the proximal root of the sciatic nerve innervating the soleus muscle. Contralateral hindlimbs were untreated and served as control. Axonal degeneration was evident within the sciatic nerve following freezing, although variable amounts of damage were observed and thin nerve fibers were observed at 3 weeks. No clear difference of morphological change of the sciatic nerve was observed in the short duration static stretching groups (group S) or the non-stretching groups (group D). The wet weight of the denervated soleus muscles progressively declined to a minimum at 2 weeks after injury (group D, 50.8 ± 8.9%; group S, 61.3 ± 4.2%) and began to reverse in the following 3 weeks. Muscle wet weight for short duration static stretching groups similarly decreased and began to reverse in the following 3 weeks. The muscle fiber cross-sectional area also similarly changed with the muscle wet weight. The type II fiber ratios of the denervated sides were consistently higher than the control levels. In non-stretching groups, type II fibers had increased by 3 weeks after denervation (49.4%), whereas type II fiber ratios of the short duration static stretching groups decreased after 3 weeks (31.3%). These data suggests that mechanical stimuli provided by short duration static stretching can prevent the atrophy of the denervated muscle over a short period. In addition, it was indicated that short duration static stretching affected the reinnervated muscle fiber type composition. However, the reinnervation took the crucial role of recovering from the atrophy and composing the integrity of the soleus muscles.
去神经支配会引发骨骼肌形态测量学的深刻改变。有证据表明，通过有节奏的拉伸对肌肉施加增加的机械负荷可减轻去神经支配引起的肌肉形态改变。为了研究短时间静态拉伸（每天40分钟）对去神经支配和重新神经支配肌肉的影响，对大鼠的比目鱼肌进行了组织化学研究。使用了21只8周龄的雌性Wistar大鼠。通过局部冷冻支配比目鱼肌的坐骨神经近端根部进行部分去神经支配。对侧后肢未处理，作为对照。冷冻后坐骨神经内轴突变性明显，尽管观察到不同程度的损伤，且在3周时观察到细神经纤维。在短时间静态拉伸组（S组）或非拉伸组（D组）中，未观察到坐骨神经形态变化的明显差异。去神经支配的比目鱼肌湿重在损伤后2周逐渐下降至最低（D组，50.8±8.9%；S组，61.3±4.2%），并在接下来的3周开始恢复。短时间静态拉伸组的肌肉湿重同样下降，并在接下来的3周开始恢复。肌纤维横截面积也与肌肉湿重有类似变化。去神经支配侧的II型纤维比例始终高于对照水平。在非拉伸组中，去神经支配3周后II型纤维增加（49.4%），而短时间静态拉伸组的II型纤维比例在3周后下降（31.3%）。这些数据表明，短时间静态拉伸提供的机械刺激可在短时间内防止去神经支配肌肉的萎缩。此外，表明短时间静态拉伸影响重新神经支配的肌纤维类型组成。然而，重新神经支配在从萎缩中恢复并构成比目鱼肌完整性方面起关键作用。
