School of Podiatry, 13014, Marseille, France.
C2VN Inra Inserm, Faculty of Medicine, Aix Marseille University, Bd. Pierre Dramard, 13916 cedex 20, Marseille, France.
Mil Med Res. 2018 Aug 17;5(1):28. doi: 10.1186/s40779-018-0175-4.
Heavy backpacks are often used by soldiers and firefighters. Weight carrying could reduce the speed and efficiency in task completion by altering the foot sole sensitivity and postural control.
In fifteen healthy subjects, we measured the changes in sensitivity to vibrations applied to the foot sole when standing upright or walking after load carrying (30% body weight). The participants were asked to judge different vibration amplitudes applied on the 2nd or 5th metatarsal head and the heel at two frequencies (25 and 150 Hz) to determine the vibration threshold and the global perceptual representation (Ѱ)of the vibration amplitude (Ф) given by the Stevens power function (Ѱ = k × Ф). Any increase in negative k value indicated a reduction in sensitivity to the lowest loads. Pedobarographic measurements, with computation of the center of pressure (COP) and its deviations, were performed during weight carrying.
The 25-Hz vibration threshold significantly increased after weight carrying when standing upright or walking. After standing with the added loads, the absolute negative k value increased for the 25 Hz frequency. After walking with the added loads, the k coefficient increased for the two vibration frequencies. Weight carrying significantly increased both the CoP surface and CoP lateral deviation.
Our data show that weight carrying reduces the sensory pathways from the foot sole and accentuates the center of pressure deviations.
士兵和消防员经常使用重载背包。负重会改变足底的敏感性和姿势控制，从而降低完成任务的速度和效率。
在 15 名健康受试者中，我们测量了在负重（体重的 30%）后站立或行走时，足底接受振动的敏感性变化。要求参与者判断在第二或第五跖骨头部和脚跟处施加的不同振动幅度，频率分别为 25 和 150 Hz，以确定振动阈值和振动幅度的全局感知表示（Ѱ）（Ѱ=k×Ф）。负 k 值的任何增加都表明对最低负荷的敏感性降低。在负重时进行足底压力测量，并计算压力中心（COP）及其偏差。
在站立或行走时，负重后 25 Hz 振动阈值显著增加。在负重站立后，25 Hz 频率的绝对负 k 值增加。在负重行走后，两种振动频率的 k 系数都增加了。负重显著增加了 COP 表面和 COP 侧向偏差。
我们的数据表明，负重会降低足底的感觉通路，并加重压力中心的偏差。
