Objective:This study aims to explore the effects of 12-week gait retraining (GR) on plantar flexion torque, architecture, and behavior of the medial gastrocnemius (MG) during maximal voluntary isometric contraction (MVIC).Methods:Thirty healthy male rearfoot strikers were randomly assigned to the GR group (n = 15) and the control (CON) group (n = 15). The GR group was instructed to wear minimalist shoes and run with a forefoot strike pattern for the 12-week GR (3 times per week), whereas the CON group wore their own running shoes and ran with their original foot strike pattern. Participants were required to share screenshots of running tracks each time to ensure training supervision. The architecture and behavior of MG, as well as ankle torque data, were collected before and after the intervention. The architecture of MG, including fascicle length (FL), pennation angle, and muscle thickness, was obtained by measuring muscle morphology at rest using an ultrasound device. Ankle torque data during plantar flexion MVIC were obtained using a dynamometer, from which peak torque and early rate of torque development (RTD50) were calculated. The fascicle behavior of MG was simultaneously captured using an ultrasound device to calculate fascicle shortening, fascicle rotation, and maximal fascicle shortening velocity (Vmax).Results:After 12-week GR, 1) the RTD50 increased significantly in the GR group (p = 0.038), 2) normalized FL increased significantly in the GR group (p = 0.003), and 3) Vmax increased significantly in the GR group (p = 0.018).Conclusion:Compared to running training, GR significantly enhanced the rapid strength development capacity and contraction velocity of the MG. This indicates the potential of GR as a strategy to improve muscle function and mechanical efficiency, particularly in enhancing the ability of MG to generate and transmit force as well as the rapid contraction capability. Further research is necessary to explore the effects of GR on MG behavior during running in vivo.

中文翻译：

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12周步态再训练对体内腓肠肌内侧跖屈扭矩、结构和行为的影响

目的：本研究旨在探讨 12 周步态再训练 (GR) 对最大自主等长收缩 (MVIC) 期间腓肠肌内侧肌 (MG) 的跖屈扭矩、结构和行为的影响。方法：30 名健康男性后足前锋被随机分配到GR组（n= 15) 和对照组 (CON) (n= 15）。 GR 组被要求穿着极简鞋并以前脚掌着地模式跑步，进行为期 12 周的 GR（每周 3 次），而 CON 组则穿着自己的跑鞋并以原来的脚掌着地模式跑步。要求参与者每次分享跑步轨迹截图，以保证训练监督。在干预前后收集 MG 的结构和行为以及踝关节扭矩数据。 MG 的结构，包括束长度 (FL)、羽状角和肌肉厚度，是通过使用超声设备测量静止时的肌肉形态来获得的。使用测力计获得跖屈 MVIC 期间的踝关节扭矩数据，从中获得峰值扭矩和早期扭矩发展率 (RTD50）进行了计算。使用超声设备同时捕获 MG 的束行为，以计算束缩短、束旋转和最大束缩短速度（V）最大限度).结果：12周GR后，1) RTD50GR组显着增加（p= 0.038), 2) GR 组中归一化 FL 显着增加（p= 0.003), 和 3) V最大限度GR组显着增加（p= 0.018）。结论：与跑步训练相比，GR显着增强了MG的快速力量发展能力和收缩速度。这表明 GR 作为改善肌肉功能和机械效率的策略的潜力，特别是在增强 MG 产生和传递力以及快速收缩能力的能力方面。需要进一步研究来探索跑步过程中 GR 对 MG 行为的影响体内。