Weinert-Aplin Robert A, Bull Anthony M J, McGregor Alison H
Department of Surgery and Cancer, Imperial College London , London, UK ; Department of Bioengineering, Imperial College London , London, UK.
Department of Bioengineering, Imperial College London , London, UK.
J Sports Sci Med. 2015 May 8;14(2):459-65. eCollection 2015 Jun.
This study aimed to characterise the biomechanics of the widely practiced eccentric heel-drop exercises used in the management of Achilles tendinosis. Specifically, the aim was to quantify changes in lower limb kinematics, muscle lengths and Achilles tendon force, when performing the exercise with a flexed knee instead of an extended knee. A musculoskeletal modelling approach was used to quantify any differences between these versions of the eccentric heel drop exercises used to treat Achilles tendinosis. 19 healthy volunteers provided a group from which optical motion, forceplate and plantar pressure data were recorded while performing both the extended and flexed knee eccentric heel-drop exercises over a wooden step when barefoot or wearing running shoes. This data was used as inputs into a scaled musculoskeletal model of the lower limb. Range of ankle motion was unaffected by knee flexion. However, knee flexion was found to significantly affect lower limb kinematics, inter-segmental loads and triceps muscle lengths. Peak Achilles load was not influenced despite significantly reduced peak ankle plantarflexion moments (p < 0.001). The combination of reduced triceps lengths and greater ankle dorsiflexion, coupled with reduced ankle plantarflexion moments were used to provide a basis for previously unexplained observations regarding the effect of knee flexion on the relative loading of the triceps muscles during the eccentric heel drop exercises. This finding questions the role of the flexed knee heel drop exercise when specifically treating Achilles tendinosis. Key pointsA more dorsiflexed ankle and a flexing knee are characteristics of performing the flexed knee heel-drop eccentric exercise.Peak ankle plantarflexion moments were reduced with knee flexion, but did not reduce peak Achilles tendon force.Kinematic changes at the knee and ankle affected the triceps muscle length and resulted in a reduction in the amount of Achilles tendon work performed.A version of the heel-drop exercise which reduces the muscle length change will also reduce the amount of tendon stretch, reducing the clinical efficacy of the exercise.
本研究旨在描述广泛应用于跟腱炎治疗的离心足跟下降练习的生物力学特征。具体而言，目的是量化在进行该练习时，屈膝而非伸膝状态下下肢运动学、肌肉长度和跟腱力的变化。采用肌肉骨骼建模方法来量化用于治疗跟腱炎的这些不同版本的离心足跟下降练习之间的差异。19名健康志愿者组成一组，在他们赤脚或穿着跑鞋在木台阶上进行伸膝和屈膝离心足跟下降练习时，记录光学运动、测力台和足底压力数据。这些数据被用作下肢比例肌肉骨骼模型的输入。踝关节活动范围不受膝关节屈曲的影响。然而，发现膝关节屈曲会显著影响下肢运动学、节段间负荷和肱三头肌长度。尽管踝关节跖屈峰值力矩显著降低（p < 0.001），但跟腱峰值负荷并未受到影响。肱三头肌长度缩短与踝关节背屈增加，再加上踝关节跖屈力矩减小，共同为先前关于膝关节屈曲对离心足跟下降练习期间肱三头肌相对负荷影响的未解释观察结果提供了依据。这一发现对屈膝足跟下降练习在专门治疗跟腱炎时的作用提出了质疑。要点屈膝足跟下降离心练习的特点是踝关节背屈增加和膝关节屈曲。膝关节屈曲时踝关节跖屈峰值力矩降低，但并未降低跟腱峰值力。膝关节和踝关节的运动学变化影响了肱三头肌长度，并导致跟腱做功量减少。一种能减少肌肉长度变化的足跟下降练习版本也会减少肌腱拉伸量，从而降低该练习的临床效果。
