Effect of hip abduction assistance on metabolic cost and balance during human walking.

The use of wearable robots to provide walking assistance has rapidly grown over the past decade, with notable advances made in robot design and control methods toward reducing physical effort while performing an activity. The reduction in walking effort has mainly been achieved by assisting forward progression in the sagittal plane. Human gait, however, is a complex movement that combines motions in three planes, not only the sagittal but also the transverse and frontal planes. In the frontal plane, the hip joint plays a key role in gait, including balance. However, wearable robots targeting this motion have rarely been investigated. In this study, we developed a hip abduction assistance wearable robot by formulating the hypothesis that assistance that mimics the biological hip abduction moment or power could reduce the metabolic cost of walking and affect the dynamic balance. We found that hip abduction assistance with a biological moment second peak mimic profile reduced the metabolic cost of walking by 11.6% compared with the normal walking condition. The assistance also influenced balance-related parameters, including the margin of stability. Hip abduction assistance influenced the center-of-mass movement in the mediolateral direction. When the robot assistance was applied as the center of mass moved toward the opposite leg, the assistance replaced some of the efforts that would have otherwise been provided by the human. This indicates that hip abduction assistance can reduce physical effort during human walking while influencing balance.

The Effects of a Custom-Designed High-Collar Shoe on Muscular Activity, Dynamic Stability, and Leg Stiffness: A Biomimetic Approach Study.

High-collar shoes are a biomimetic approach to preventing lateral ankle injuries during high-demand activities; however, the influence of collar stiffness (CS) on parameters related to lateral ankle sprain prevention during running remains unclear. In this study, we investigated the effects of a custom-designed shoe CS on muscular activity, dynamic stability, and leg stiffness (Kleg) during running using a biomimetic design approach inspired by the mechanisms of ankle sprain prevention. Sixteen healthy male participants ran on a treadmill while wearing a custom-designed high-collar shoe with low, medium, and high CS conditions, measured using circumferential ankle pressure (CAP). Lower extremity kinematics and electromyography (EMG) data were recorded simultaneously. One-way repeated-measures ANOVA was conducted to compare the CS conditions. Results indicate that high and medium CS conditions significantly reduce sagittal and frontal ankle ranges of motion (ROMs) compared to the low CS condition, providing improved stability and support against lateral ankle sprain; moreover, there was a trend towards higher dynamic stability and Kleg with increasing CS. Our study highlights the importance of considering the CAP in regulating high-collar stiffness properties and how higher CS may provide better support for the ankle during running. Nevertheless, additional research is necessary to validate the efficacy of the current design in preventing ankle sprains during high-demand activities.

Influence of circumferential ankle pressure of shoe collar on the kinematics, dynamic stability, electromyography, and plantar pressure during normal walking.

BACKGROUND: The shoe's collar plays a significant role in supporting the ankle during walking. Since the protective effect of the collar requires the circular embracing of the ankle and shank, a stiffer collar might be involved with increased circumferential ankle pressure (CAP). It is not clear how collar CAP affects walking performance. Therefore, this study was aimed at examining the influence of the collar CAP on the kinematics, dynamic stability, electromyography (EMG), and plantar pressure during normal walking. METHOD: Sixteen healthy male participants walked on a treadmill while wearing a custom-designed high-collar shoe with 10 (low), 30 (medium), and 60 mmHg (high) CAP conditions, and the joint angles, dynamic stability index, EMG, and plantar pressure were measured. RESULT: While the low CAP condition did not affect the ankle range of motion (ROM), The high CAP condition restricted both the ankle sagittal and frontal ROM, whereas the medium CAP condition limited only the ankle frontal ROM. The knee and hip ROM did not differ between conditions. The dynamic stability for the high and medium CAP cases was comparable but significantly higher than that of the low CAP condition. The ankle muscle activity and corresponding co-contraction increased with increasing CAP for gastrocnemius medialis (GM), soleus (SOL), peroneus longus (PL), tibialis anterior (TA) muscles in the weight acceptance and push-off phases but not in the single limb support. Knee muscle activity, including vastus lateralis (VL) and semitendinosus (SEMI) was similar between all conditions. A higher relative pressure was observed under the lateral aspect of the heel when walking in the high CAP condition. CONCLUSION: The results suggest that a high-collar shoe with a high CAP may not be an appropriate choice for walking owing to the injury risk factors and limited walking efficiency. A medium CAP is associated with certain advantages and, thus, a superior choice for high-collar shoe design.