Biomechanics of Running with a Commercially Available Non-Custom Athletic Footwear Insole

Abstract

A commercially available non-custom athletic footwear (AF) insole has recently been developed and is claimed to help prevent and treat running injuries such as patellofemoral pain syndrome (PFPS), plantar faciitis (PF), and tibial stress syndrome (TSS); however, no data are available to support whether these insoles influence biomechanical variables associated with these injuries. PURPOSE: To determine if the AF insole alters biomechanical variables associated with PFPS, PF and TSS. METHODS: Fifteen uninjured participants completed 5 trials running at 4m/s along a 30m runway with each of two conditions: (1) their own running shoe, control (CON), and (2) #1 with the AF insole placed within the shoe. As participants ran, 3D trajectories of the participant’s right lower leg and foot, and 3D ground reaction force data were recorded. Kinetic and kinematic data were used to calculate the following biomechanical variables: (1) knee abduction angular impulse during stance phase (associated with PFPS), (2) peak foot eversion angle during stance phase (associated with PF and TSS), and (3) peak foot eversion velocity during stance (associated with TSS). Two-tailed paired-samples t-tests were used to compare the CON and AF insole conditions. RESULTS: No significant differences were observed between the CON and AF insole conditions for knee abduction angular impulses (CON: 10.3±5.4 Nms, AF insole: 9.6±4.7 Nms, p=0.26), peak foot eversion angles (CON: 11.1±4.5 deg, AF insole: 10.8±4.3 deg, p=0.64) or peak foot eversion velocities (CON: 378±108 deg/s, AF insole: 408±122 deg/s, p=0.06). However, individually, many participants (7/15 for knee abduction angular impulse, 11/15 for peak foot eversion and eversion velocity) experienced relevant biomechanical changes of ± 10% or more with the AF insole. CONCLUSIONS: AF insoles have an influence on biomechanical variables associated with PFPS, PF or TSS for individual runners; however, their influence is not systematic across participants. Consequently, the AF insoles may offer benefit to some runners, but be detrimental to others.