Objective: To explore the effect of different intensity treadmill training on the repair of micro-injured Achilles tendon induced by collagenase in rats.
Methods: Seventy-two 8-week-old male Sprague Dawley rats (weighing, 200-250 g) were selected. After adaptive treadmill training for 1 week, rats were injected with 30 μL type I collagenase solution (10 mg/mL) into both Achilles tendons to make micro-injured Achilles tendon models. After 1 week of cage feeding, the rats were randomly divided into 3 groups: the control group, the low-intensity group, and the high-intensity group, 24 rats each group. The rats in control group could move freely, and the rats underwent daily treadmill training at the intensity of 13 m/min and 20 min/d in the low-intensity group and at the intensity of 17 m/min and 60 min/d in the high-intensity group. At immediate, 1 week, and 4 weeks after training, bilateral Achilles tendons were collected from 8 rats of each group for gross observation, histological analysis, and mechanical testing.
Results: At immediate after training, there was no significant difference in the gross observation, histological observation, and biomechanical properties of the Achilles tendon between groups ( P>0.05). The gross observation showed connective tissue hyperplasia near Achilles tendon and lackluster tendon in each group at 1 week; hyperplasia significantly reduced in the low-intensity group when compared with the control group, and there were more connective tissue and a large number of neovascularization in the high-intensity group at 4 weeks. At 1 week, there was no significant difference in the semi-quantitative histological total score between groups ( P>0.05), but there were significant differences in vascularity between low-intensity group or high-intensity group and control group ( P<0.05). At 4 weeks, the semi-quantitative histological total score was significantly higher in high-intensity group than control group and low-intensity group ( P<0.05), and in control group than low-intensity group ( P<0.05). There were significant differences in collagen arrangement, cell morphology, abnormal cells, and vascularity between low-intensity group and high-intensity group or control group ( P<0.05). And there was significant difference in abnormal cells between high-intensity group and control group ( P<0.05). The mechanical testing showed that there was no significant difference in cross-sectional area of the Achilles tendon, the ultimate force, tensile strength, and elastic modulus between groups at 1 week ( P>0.05); the low-intensity group was significantly higher than the control group in the ultimate force and the tensile strength ( P<0.05), and than high-intensity group in the ultimate force and elastic modulus ( P<0.05), but no significant difference was found in the other indexes between groups ( P>0.05) at 4 weeks.
Conclusion: Low-intensity treadmill training can promote the repair of rat micro-injured Achilles tendon induced by collagenase.
目的: 探讨不同强度跑台训练对胶原酶诱导的大鼠跟腱微损伤修复的影响。.
方法: 取 8 周龄雄性 SD 大鼠 72 只，体质量 200～250 g，经适应性跑台训练 1 周后，于双侧跟腱各注射 30 μL 浓度为 10 mg/mL 的Ⅰ型胶原酶溶液，制备胶原酶诱导的跟腱微损伤模型。饲养 1 周后随机分为对照组（ n=24）、低强度组（ n=24）、高强度组（ n=24）；对照组大鼠可自由活动；低、高强度组采用计算机控制动物实验跑台对大鼠进行被动跑台训练，其中低强度组跑台强度为 13 m/min、20 min/d，高强度组跑台强度为 17 m/min、60 min/d。于训练开始即刻及 1、4 周，每组各取 8 只大鼠双侧跟腱，行大体观察、组织学观察并半定量评分以及生物力学测试。.
结果: 训练开始即刻，各组跟腱标本大体观察、组织学观察及半定量评分以及生物力学测试比较，差异均无统计学意义（ P>0.05），提示各组跟腱微损伤模型损伤程度相似，具有可比性。大体观察示，1 周时，各组腱旁结缔组织增生、肌腱组织缺乏光泽；4 周时，低强度组腱旁增生组织较对照组明显减少，而高强度组腱旁结缔组织较多，并且有大量新生血管形成。组织学观察示，1 周时各组间总分比较差异无统计学意义（ P>0.05）；低、高强度组仅新生血管量评分与对照组比较，差异有统计学意义（ P<0.05）。4 周时，高强度组总分明显高于对照组、低强度组，对照组显著高于低强度组（ P<0.05）；低强度组纤维排列、细胞形态、细胞异常增多、新生血管量评分与对照组、高强度组比较，高强度组细胞异常增多评分与对照组比较，差异有统计学意义（ P<0.05）。生物力学测试示，1 周时各组跟腱横截面积、最终应力、抗拉强度及弹性模量比较，差异均无统计学意义（ P>0.05）。4 周时，低强度组最终应力及抗拉强度较对照组明显升高（ P<0.05），最终应力及弹性模量较高强度组明显升高（ P<0.05）；其余各指标组间比较差异均无统计学意义（ P>0.05）。.
结论: 低强度跑台训练能够促进胶原酶诱导的大鼠跟腱微损伤的修复。.
Keywords: Achilles tendon; Tendinopathy; rat; tendon micro-injury; treadmill training.