Correction: Stiffness Effects in Rocker-Soled Shoes: Biomechanical Implications

Comparing the Lower-Limb Muscle Activation Patterns of Simulated Walking Using an End-Effector-Type Robot with Real Level and Stair Walking in Children with Spastic Bilateral Cerebral Palsy

Cerebral palsy is a neurologic disorder caused by lesions on an immature brain, often resulting in spasticity and gait abnormality. This study aimed to compare the muscle activation patterns of real level and stair walking with those of simulated walking using an end-effector-type robot in children with spastic cerebral palsy. The electromyographic activities of the vastus lateralis, biceps femoris, tibialis anterior and medial gastrocnemius of nine children with spastic bilateral cerebral palsy were measured during gait using a wireless surface EMG device. Morning walk was used for the simulated gait. Differences in the muscle activation patterns between the real and simulated gait conditions were analyzed. In the loading response, all four muscles showed reduced activity during two simulated conditions. In mid-stance, mGCM showed reduced activity during simulated conditions, whereas BFem showed greater activity during simulated level walking. In the swing phase, BFem and TAnt activity was reduced during the simulated conditions. The onset-offset of the VLat, BFem and TAnt activity was significantly delayed during simulated versus real level walking. No differences in activity onset-offset were observed between the simulated level and stair conditions. In conclusion, the robot-simulated gait showed differences in its muscle activation patterns compared with the real gait conditions, which must be considered for gait training using an end-effector-type robot.

Complexity of spatio-temporal plantar pressure patterns during everyday behaviours

The human foot sole is the primary interface with the external world during balance and walking, and also provides important tactile information on the state of contact. However, prior studies on plantar pressure have focused mostly on summary metrics such as overall force or centre of pressure under limited conditions. Here, we recorded spatio-temporal plantar pressure patterns with high spatial resolution while participants completed a wide range of daily activities, including balancing, locomotion and jumping tasks. Contact area differed across task categories, but was only moderately correlated with the overall force experienced by the foot sole. The centre of pressure was often located outside the contact area or in locations experiencing relatively low pressure, and therefore a result of disparate contact regions spread widely across the foot. Non-negative matrix factorization revealed low-dimensional spatial complexity that increased during interaction with unstable surfaces. Additionally, pressure patterns at the heel and metatarsals decomposed into separately located and robustly identifiable components, jointly capturing most variance in the signal. These results suggest optimal sensor placements to capture task-relevant spatial information and provide insight into how pressure varies spatially on the foot sole during a wide variety of natural behaviours.

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 standard 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 standard shoes during jogging. The experimental groups showed larger PP or PTI in the foot regions examined except in the lateral forefoot. Also, increases the in the contact area of the midfoot with decreases in the contact area in heel were also observed. 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 indicate 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.