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目的:观察前脚掌着地的运动员穿极简鞋和传统跑鞋在50km跑中跑步姿势、压力特征、表面肌电图(EMG)记录、步幅特征等方面的改变。方法:选取4名有穿极简鞋跑步经验的受试者,每人都穿极简鞋和传统跑鞋模拟50km跑。每次测试都在初始0.8km和最后0.8km收集压力数据、表面EMG记录和限定三维动作捕捉数据。结果:在50km跑之后,分别有3人和1人在穿传统跑鞋和极简鞋条件下初始着地面积靠后(中足部着地),数据支持来自着地前阶段胫骨前肌活动(均方根值)的增加。此外,穿极简鞋的受试者在跑前和跑后均出现峰值压力增加,特别是在前脚内侧。肌疲劳(定义为等距恒力收缩时测得的中值频率下降)在与跑步姿势改变的相关性方面与研究假设不一致。最后,两种跑鞋条件下,受试者在50km跑之后均出现步频增大、步长减小。结论:与穿极简鞋相比,受试者在穿传统跑鞋跑50km时,更多倾向于采用较为靠后的初始着地方式。采取靠后着地方式的受试者,其内侧腓肠肌的中值频率得到增强,这表明长距离持续的速度跑条件下,运动单位的补充模式发生变化。值得注意的是,由于穿极简鞋采用中足部着地的跑步者峰值压力增强,因此训练设置一定要科学合理,否则很可能引起跖骨应力性骨折。
OBJECTIVE: To observe the change of running posture, pressure characteristics, surface electromyography (EMG) recording, stride characteristics and other aspects of athletes wearing forefoot to wear simple shoes and traditional running shoes in 50km running. Methods: Four subjects with running experience wearing a minimalist shoe were selected, each wearing a minimalist shoe and a traditional running shoe simulating a 50km run. For each test, pressure data was collected at the initial 0.8km and the last 0.8km, and the surface EMG recorded and defined the 3D motion capture data. RESULTS: After 50 km of run, three and one of them, respectively, had a lower initial ground area (midfoot and midfoot) under traditional running shoes and minimalist shoes. The data provided support for activities from the anterior tibialis anterior muscle (root mean square Value) increase. In addition, subjects wearing a minimalist shoe experienced an increase in peak pressure both before and after the run, especially on the medial frontal. Muscle fatigue (defined as a decrease in median frequency measured at isometric contractions of constant force) is inconsistent with the hypothesis of study in relation to the change in running posture. Finally, under both conditions of running shoes, the pace frequency increases and the step length decreases after the subjects run at 50 km. CONCLUSIONS: Compared with wearing simple shoes, subjects wearing traditional running shoes running 50km, the more inclined to adopt a more initial approach to the ground. Median gastrocnemius medial frequencies were enhanced in subjects taking the rearward approach, indicating a change in motor unit replenishment patterns over long distances. It is noteworthy that, due to wearing a minimalist shoes with midfoot foot runner peak pressure increase, so the training set-up must be scientific and reasonable, otherwise it is likely to cause stress fracture of the metatarsal.