A focused comparison of mechanical and human-centered slip resistance testing for winter footwear

Falls represent a major public health concern, with up to 50% caused by slips, specifically, traction loss between shoe soles and walking surfaces. While mechanical testing devices provide standardized measurements of footwear slip resistance, they often lack biofidelity compared to human-centered assessments. This study investigated the relationship between mechanical and human-centered slip resistance measurements across different types of winter footwear and ice conditions. Fifty pairs of winter footwear across five outsole material types were evaluated using both mechanical and human-centered testing. Human testing was conducted using a tilting ice walkway to determine Maximum Achievable Angle (MAA) under wet and dry ice conditions. A deep learning-based pose estimation was used to calculate the center of mass acceleration from the recorded videos of walking trials, enabling conversion of MAA to the dynamic Coefficient of Friction (COF). Mechanical testing measured dynamic COF using ASTM F2913 protocol with controlled vertical forces and sliding speeds. Overall correlations between mechanical COF MECH and human-centered COF MAA were moderate but consistent. Stronger relationships were observed when acceleration was incorporated into the human-centered measurements compared to using MAA alone. Additionally, a stronger correlation between the two testing methods was observed under dry ice condition. Bland-Altman analysis indicated systematic underestimation of mechanical COF compared to human-centered measures, with greater bias under wet ice condition (-0.27) than dry ice condition (-0.22). These findings underscore the need for human-centered assessments to improve the biofidelity of slip resistance testing, enabling more accurate performance benchmarking, better outsole design, and safer winter footwear. • The relationship between mechanical and human-centered slip-resistance testing methods for winter footwear on icy surfaces was found to be low to moderate across different calculation approaches. • Material-specific behaviors of footwear must be considered when evaluating slip resistance. • Combining mechanical testing with human-centered measures provides a more comprehensive footwear performance assessment • Vision-based measurement offers a scalable, flexible alternative to traditional biomechanical equipment.