McKay Orthopaedic Research Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania.
McKay Orthopaedic Research Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania
J Appl Physiol (1985). 2017 Oct 1;123(4):757-763. doi: 10.1152/japplphysiol.00368.2017. Epub 2017 Jun 29.
The objective of this study was to identify acute responses and chronic adaptations of supraspinatus tendon to noninjurious exercise. We hypothesized that chronic exercise (EX) increases tendon mechanical properties, and a single exercise bout increases matrix metalloproteinase (MMP) activity acutely. Rats were divided into acute or chronic EX or cage activity groups. Animals in acute EX groups were euthanized, 3, 12, 24, 48, or 72 h upon completion of a single bout of exercise (10 m/min, 1 h) on a flat treadmill. Animals in chronic EX groups walked on a flat treadmill for 3 days or 1, 2, or 8 wk. Tendon histology, MMP activity, and mechanics were measured. A single bout of exercise trended toward reducing tendon mechanical properties, but 2 or 8 wk of chronic EX increased tendon mechanics. Cell density was not affected. Cells became rounder with chronic EX. All tendons were highly organized. MMP activity decreased after a single bout of exercise and returned to baseline by 72 h. MMP activity decreased after 8 wk of chronic EX. Decreased MMP activity may indicate an anabolic instead of catabolic response in contrast to injury. Results suggest that mild, acute decreases in MMP activity and tendon mechanics following a single exercise bout lead to enhanced tendon mechanical adaptations with repeated exercise bouts. This study defines acute and chronic changes of MMP activity, mechanical properties, and histology of the rat supraspinatus tendon in response to beneficial exercise and proposes a mechanism by which acute responses translate to chronic adaptations. The line between beneficial exercise and overuse has not been elucidated. This study defines the acute and chronic temporal response to exercise of supraspinatus tendon in an in vivo model. We found that decreased matrix metalloproteinase activity and tendon mechanics after a single bout of exercise are followed by beneficial chronic adaptations of the tendon with repeated bouts. How the acute responses to exercise lead to chronic adaptations may distinguish beneficial exercise from overuse.
本研究旨在确定冈上肌腱对非损伤性运动的急性反应和慢性适应。我们假设慢性运动（EX）会增加肌腱的机械性能，而单次运动可使基质金属蛋白酶（MMP）活性在短期内增加。将大鼠分为急性或慢性 EX 或笼活动组。急性 EX 组的动物在完成单次运动（10 m/min，1 h）后 3、12、24、48 或 72 h 时安乐死，在平坦的跑步机上运动。慢性 EX 组的动物在平坦的跑步机上行走 3 天或 1、2 或 8 周。测量肌腱组织学、MMP 活性和力学性能。单次运动有降低肌腱机械性能的趋势，但 2 或 8 周的慢性 EX 可增加肌腱力学性能。细胞密度不受影响。慢性 EX 后细胞变得更圆。所有的肌腱都高度有序。单次运动后 MMP 活性下降，72 h 后恢复基线。8 周慢性 EX 后 MMP 活性下降。MMP 活性的降低可能表明与损伤相反，在重复运动后出现了合成代谢而不是分解代谢反应。结果表明，单次运动后 MMP 活性和肌腱力学的轻度急性降低会导致随着重复运动的进行而增强肌腱的机械适应性。本研究定义了有益运动对大鼠冈上肌腱 MMP 活性、机械性能和组织学的急性和慢性变化，并提出了一种急性反应转化为慢性适应的机制。有益运动和过度使用之间的界限尚未阐明。本研究在体内模型中定义了冈上肌腱对运动的急性和慢性时间反应。我们发现，单次运动后 MMP 活性和肌腱力学的降低，随后是肌腱的有益慢性适应，这与重复运动有关。运动的急性反应如何导致慢性适应可能会区分有益运动和过度使用。
