Effects of different hardness in bionic soles on lower limb biomechanics

The design of modern footwear seems to have an excessive protective effect on the function of the foot. The purpose of this study was to examine how bionic shoes designed would influence the biomechanical index of gait patterns. There were 10 male subjects underwent gait analysis. Normal sports shoes (NS) with flat-soles were selected as control shoes. The experimental shoes comprising of two elasticity levels were defined as soft-sole bionic shoes (SS) and hard-sole
bionic shoes (HS). We examined ground reaction forces, plantar pressures and angles of the ankle, knee and hip during walking and jogging conditions. In comparison with control shoes, wearing bionic shoes reduced the range of motion in some joints during movement and changed the peak angle in the sagittal, frontal and horizontal planes. Moreover, the vertical average loading rates were significantly larger than that of the control shoes during jogging. The experimental groups showed larger peak pressure (PP) or pressure time integral (PTI) in the foot regions examined except in the lateral forefoot. Moreover, the experimental groups has larger contact area of the midfoot and smaller contact area in heel. In some regions of the foot, the hard sole of the bionic shoes had a
lower pressure than that of the soft sole. These findings indicated that the design of the bionic sole in this study can be used to increase toe scratching ability, increase neuromuscular strength and enhance stability and proprioceptive ability. However, the higher plantar pressures in some regions
may increase the risk of overuse injuries. The findings from the study indicate preference for the hard bionic shoes during exercise compared to the soft sole.