Queensland Cerebral Palsy and Rehabilitation Research Centre, Child Health Research Centre, The University of Queensland, Brisbane, Australia; Centre for Sensorimotor Neuroscience, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Australia.
Queensland Cerebral Palsy and Rehabilitation Research Centre, Child Health Research Centre, The University of Queensland, Brisbane, Australia; School of Health Medical and Applied Science, Central Queensland University, Bundaberg, Australia.
Gait Posture. 2020 Mar;77:83-88. doi: 10.1016/j.gaitpost.2019.12.032. Epub 2020 Jan 7.
INTRODUCTION/AIM: Flip-flops are a popular choice of footwear for children. However, their inherent design provides minimal support to the foot and ankle and has been suggested to increase the work performed by muscle and tendon structures, potentially predisposing them to injury. Therefore, the aim of this study was to compare the length change behaviour of the medial gastrocnemius (MG) muscle fascicles and muscle tendon unit (MTU) and their mechanical function at the ankle and subtalar joints in children during walking with and without flip-flop.
Eight healthy children walked barefoot and with flip-flops whilst 3D gait analysis and simultaneous B-mode ultrasound images of the MG fascicles during level walking were collected. Joint kinematics, kinetics and MTU lengths were analysed using musculoskeletal modelling and fascicle lengths using a semi-automated tracking algorithm.
The muscles and tendons across the ankle absorbed greater amounts of power during barefoot walking compared to flip-flop walking. The muscle activations of the lateral gastrocnemius, soleus and tibialis anterior remained invariant across the conditions as did the activation, and fascicle length change behaviour of the medial gastrocnemius. In the barefoot condition, there was a trend of greater MTU lengthening, to potentially absorb greater amounts of power, although no differences in shortening was observed during late stance.
Walking with flip-flops does not increase the mechanical work performed by the MG muscle at the ankle and subtalar joints, suggesting that flip-flops do not increase the stresses and strains of the Achilles tendon and hence its predisposition to strain induced injury. Instead, our results suggest that flip-flops, act as a compliant surface and absorb energy during contact and hence the strain experienced by the Achilles tendon.
简介/目的：人字拖是儿童流行的鞋类选择。然而，它们固有的设计为人脚和脚踝提供的支撑很少，并被认为会增加肌肉和肌腱结构的工作量，从而使它们更容易受伤。因此，本研究的目的是比较儿童在行走时穿着人字拖和不穿人字拖时，内侧腓肠肌（MG）肌束和肌腱单元（MTU）的长度变化行为及其在踝关节和距下关节的力学功能。
8 名健康儿童赤脚和穿着人字拖行走时，同时采集 3D 步态分析和水平行走时 MG 肌束的 B 型超声图像。使用肌肉骨骼建模分析关节运动学、动力学和 MTU 长度，使用半自动跟踪算法分析肌束长度。
与穿人字拖相比，赤脚行走时，踝关节和距下关节的肌肉和肌腱吸收了更多的能量。外侧腓肠肌、比目鱼肌和胫骨前肌的肌肉激活在两种情况下保持不变，内侧腓肠肌的激活和肌束长度变化行为也保持不变。在赤脚条件下，MTU 有更大的伸长趋势，可能吸收更多的能量，尽管在后期站立时没有观察到缩短的差异。
穿人字拖不会增加 MG 肌肉在踝关节和距下关节的机械功，这表明人字拖不会增加跟腱的应力和应变，从而不会增加跟腱受伤的倾向。相反，我们的结果表明，人字拖充当了一个顺应性表面，在接触时吸收能量，从而减轻了跟腱所经历的应变。
