The Role of Footwear and Walking Velocity on Healthy Ankle and Multi-Segment Foot Energetics
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Abstract
The human foot is a complex set of structures that operates collectively to ensure our ability to walk at a range of velocities by absorbing, generating, and transferring energy. Healthy foot energetics can be disrupted by a range of conditions that also commonly result in decreased walking velocity. Individuals with impaired foot and ankle mechanics often choose to wear athletic shoes because of their ability to work in conjunction with prescribed devices, such as orthoses, to fulfill patients’ specific footwear needs. Some shoe designs have recently attempted to enhance foot energetics by increasing the shoe’s stiffness with deformable foot orthoses (DFO) made from carbon fiber. A key aspect of DFOs is their ability to store mechanical energy through deformation, then rebound, returning the energy to the foot. The overall purpose of this dissertation was to explore the impact of increasing footwear stiffness with DFOs on the energetics within the foot itself. Additionally, we characterized foot energetics with increasing velocities while walking in athletic-style walking shoes to help understand the energetic changes within the foot necessary to achieve a functional gain in walking velocity. Customized DFOs were fabricated for ten healthy participants who walked under four footwear conditions (minimalist shoes, walking shoes, minimalist shoes with DFOs, walking shoes with DFOs), while motion and ground reaction force data were collected. Additionally, 20 healthy participants walked in walking shoes at four height-normalized velocities (0.4, 0.6, 0.8, 1.0 statures/sec), while motion and ground reaction force data were collected. MTP positive work increased with increasing stiffness, whereas MTP negative work and ankle positive work decreased. Midtarsal negative work decreased in both walking shoe conditions, while ankle negative work increased under the same conditions. When participants walked at increasing velocities, MTP positive and negative work, midtarsal positive work, and ankle positive work increased. There were no changes in midtarsal negative work with increased velocity. While walking shoes with DFOs were the most beneficial footwear condition, the smaller overall gains in the MTP and midtarsal energetics were modest compared to the substantial increases in midtarsal and ankle positive work with increased velocity. These smaller increases in foot energetics from DFO use are likely insufficient to propel the entire body forward at a faster rate.