Dual-hardness midsole design for thermal comfort and running performance in cold weather

Overview

This research proposes a novel dual or graded midsole hardness design for running shoes, combining a softer outersole with a harder innersole or insole. The concept addresses a key challenge faced by runners in cold weather: maintaining foot thermal comfort while preserving running performance. Current footwear advice for cold climates focuses primarily on clothing, with limited evidence on how midsole materials affect thermal comfort. By engineering midsole hardness to balance thermal conductance and insulation, this approach aims to keep runners warmer and more comfortable, supporting continued training through winter conditions and reducing cold-weather injury risk.

Technical specifications

Core design principle:

• A softer outer midsole layer provides insulation from cold ground surfaces
• A harder inner midsole or insole layer retains heat generated by the foot
• The dual-hardness configuration aims to optimise both thermal comfort and mechanical performance

Scientific basis:

• Denser materials tend to conduct heat more effectively due to increased particle collisions
• EVA midsole materials become stiffer at sub-zero temperatures, which can alter running biomechanics and increase injury risk
• Midsole hardness is known to influence running kinetics and kinematics, though its isolated thermal effects are not yet well documented

Validation methodology:

• Mechanical testing of midsole properties at matched cold-weather temperatures
• Real-world 5km running trials at threshold pace in cold environments with mixed shoe ordering across visits
• Infrared thermography to assess foot temperature and blood flow
• Perceived thermal comfort monitoring during runs
• Indirect calorimetry via breath-by-breath analysis to evaluate performance

Technology readiness level

This concept is at an early research stage. The hypothesis has not yet been validated in footwear science. A structured research plan is in place to test the dual-hardness midsole design through controlled mechanical assessments and real-world running trials with regular runners. The work will generate foundational data on how midsole hardness influences thermal comfort and running performance in cold climates, providing a basis for future footwear product development.