Crouzier Marion, Baudry Stéphane, Vanwanseele Benedicte
Laboratory of Applied Biology, Research Unit in Applied Neurophysiology, Faculty of Human Movement Sciences, Université Libre de Bruxelles (ULB), Brussels, BELGIUM.
Human Movement Biomechanics Research Group, Department of Movement Sciences, KU Leuven, Leuven, BELGIUM.
Med Sci Sports Exerc. 2025 Aug 1;57(8):1636-1645. doi: 10.1249/MSS.0000000000003717. Epub 2025 Apr 3.
Previous work showed altered mechanical properties of the Achilles tendon in the presence of tendinopathy, considering the Achilles tendon as a homogeneous structure with the gastrocnemius medialis (GM) subtendon representative of it. However, the Achilles tendon consists of three semi-independent structures: the GM, gastrocnemius lateralis (GL), and soleus (SOL) subtendons, each independently pulled by their respective muscle. The aim of this study was (i) to compare the mechanical properties of the different Achilles subtendons in humans in vivo by considering the force of each muscle within the triceps surae group and (ii) to determine whether the loss of stiffness in the presence of tendinopathy is specific to individual subtendons. We hypothesized that (i) stiffness would differ between subtendons in healthy participants and that (ii) the loss of stiffness in people with Achilles tendinopathy compared with healthy controls would not affect the three subtendons identically.
Fourteen participants with tendinopathy and 14 controls performed ramped isometric plantarflexions. Simultaneously, the elongation of the three subtendons was recorded, and an estimate of the force pulling on each was made (from muscle activation and volume). Stiffness was calculated from the individual muscle index of force-subtendon elongation relationships.
Results showed that regardless of the group, SOL stiffness was significantly higher than stiffness of both gastrocnemii (muscle effect: P < 0.001). A muscle-group interaction showed specific loss of stiffness of GL in Achilles tendinopathy compared with controls ( P = 0.029, d = 1.3), with no between-group difference for GM or SOL (both P > 0.925, d = 0.3).
This study supports the hypothesis that the biomechanical properties of the Achilles tendon differ between subtendons and further shows that the loss of stiffness in Achilles tendinopathy is specific to the GL subtendon.
先前的研究表明，在跟腱病存在的情况下，跟腱的力学性能会发生改变，该研究将跟腱视为一个均质结构，以内侧腓肠肌（GM）肌腱代表整个跟腱。然而，跟腱由三个半独立结构组成：GM、外侧腓肠肌（GL）和比目鱼肌（SOL）肌腱，每个肌腱分别由各自的肌肉独立牵拉。本研究的目的是：（i）通过考虑小腿三头肌群中每块肌肉的力量，比较人体不同跟腱在体内的力学性能；（ii）确定跟腱病时刚度的降低是否特定于单个肌腱。我们假设：（i）健康参与者的不同肌腱之间刚度会有所不同；（ii）与健康对照组相比，跟腱病患者的刚度降低对三个肌腱的影响并不相同。
14名跟腱病患者和14名对照组参与者进行了斜坡式等长跖屈运动。同时，记录三个肌腱的伸长情况，并估算牵拉每个肌腱的力量（根据肌肉激活和体积）。根据力量-肌腱伸长关系的个体肌肉指数计算刚度。
结果表明，无论组别如何，SOL的刚度均显著高于两块腓肠肌的刚度（肌肉效应：P < 0.001）。肌肉组间交互作用显示，与对照组相比，跟腱病患者的GL刚度有特定降低（P = 0.029，d = 1.3），GM或SOL在组间无差异（均为P > 0.925，d = 0.3）。
本研究支持以下假设，即跟腱的生物力学特性在不同肌腱之间存在差异，并且进一步表明跟腱病时刚度的降低特定于GL肌腱。
