The position of medial dual density midsole elements in running shoes does not influence biomechanical variables

Although the concept of dual density as medial support has barely been considered in footwear biomechanics research and lacks scientific proof of functionality, it has been established as a commercially popular system to influence rearfoot motion in running shoes. The goal of this study was to analyse the influence of systematically varied positions of medial dual density midsole elements in running shoes on kinematic and kinetic running variables. Seven identical running shoes with midsole density of 52 Asker C were systematically modified by incorporating medial midsole elements with dual density of 62 Asker C. The dual density position varied from rearfoot to midfoot in six of seven shoes; one shoe remained without medial dual density midsole element. Statistical procedures included nonparametric Friedman tests and repeatability coefficients, which are recommended for use as an indicator for strength of association of measured effect in investigations. Results showed no reduction and no linear trend in the measured rearfoot motion variables across shoe conditions. Hence, the effectiveness of medial dual density applications to alter rearfoot motion variables during running remains questionable.