Running Shoe Midsole Stiffness Zoning to Reduce Ankle Angle Change
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Solution Overview
Problem
Existing shoes fail to adequately reduce the change in angle of the ankle joint from landing to taking off during running, leading to increased foot fatigue.
Innovation Solution
A sole design with a midsole featuring a first support portion with a lower elastic modulus than a second support portion, a boundary portion passing through the thenar region, and a buffer layer, along with a plate for enhanced stability and uniform load distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a uniform midsole structure is used, then the shoe structure is simple, but the ankle joint angle change from landing to taking off cannot be adequately reduced
Solution Approach 1:
The midsole is divided into multiple support portions (first support portion, second support portion, third support portion) with different elastic moduli arranged in the foot length direction. This segmentation allows each portion to independently control ankle joint movement at different phases of the gait cycle, reducing the overall angle change while maintaining structural manageability through zoned functionality.
Solution Approach 2:
Different regions of the midsole are assigned different elastic moduli to match the local mechanical requirements of foot movement. The first support portion (lower elastic modulus) provides cushioning during landing, while the second and third support portions (higher elastic modulus) provide stability during takeoff, creating local quality variations that optimize ankle joint control throughout the gait cycle.
2Reliability
If the boundary portion between support portions does not pass through the thenar region, then the manufacturing is simpler, but the load distribution and stability are reduced
Solution Approach 1:
The boundary portion between the first and second support portions is specifically positioned to pass through the thenar region of the foot. This location corresponds to a natural pressure distribution zone, allowing the transition between different elastic modulus regions to align with the foot's natural load-bearing anatomy, thereby improving load distribution uniformity while the boundary follows a definable anatomical landmark.
3Object-affected harmful factors
If a single elastic modulus is used throughout the midsole, then the material selection and manufacturing are easier, but the foot fatigue reduction is insufficient
Solution Approach 1:
The midsole is segmented into multiple support portions with different elastic moduli arranged sequentially in the foot length direction. This segmentation creates a progressive stiffness profile that manages foot fatigue by providing compliant support during impact absorption (lower elastic modulus regions) and stable support during propulsive phases (higher elastic modulus regions), reducing overall fatigue without requiring complex multi-material construction.
Solution Approach 2:
The elastic modulus parameter is varied across different regions of the midsole to optimize fatigue reduction. By changing the stiffness parameter from lower values in the first support portion to higher values in the second and third support portions, the midsole adapts to different mechanical demands during the gait cycle, effectively reducing foot fatigue through parameter optimization rather than structural complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design reduces the change in ankle joint angle from landing to taking off, minimizing foot fatigue and providing improved stability and comfort during running.
Implementation Method 1
the first support portion has an elastic modulus lower than an elastic modulus of the second support portion
Data Source
AI summary
A sole includes a midsole. The midsole includes: a first support portion that is configured to support a front portion of an MP joint of a wearer's foot; and a second support portion that is configured to support a rear portion of the MP joint of the wearer's foot, the second support portion having a shape extending rearward from the first support portion in a foot length direction. The first support portion has an elastic modulus lower than an elastic modulus of the second support portion. The midsole includes a thenar region surrounded by a first portion, a second portion, a third portion, and a fourth portion. A boundary portion between the first support portion and the second support portion passes through the thenar region.