EFFECT OF SHOE INSERT CONSTRUCTION ON FOOT AND LEG MOVEMENT

Purpose: The purpose of this study was to quantify changes in foot eve rsion and tibial rotation during running resulting from systematic cha nges of material composition of five shoe inserts of the same shape, M ethods: Tests were performed with 12 subjects. The inserts had a bilay er design using two different materials at the top and bottom of the i nsert. The functional kinematic variables examined in this study were the foot-leg in-eversion angle, beta, and the leg-foot tibial rotation , rho. Additionally, the subject characteristics of arch height, relat ive arch deformation, and active range of motion were quantified. The statistical analysis used was a two way repeated measures MANOVA (with in trials and inserts). Results: The average group changes resulting f rom the studied inserts in total shoe eversion, total foot eversion, a nd total internal tibial rotation were typically smaller than 1 degree s when compared with the no-insert condition and were statistically no t significant. The measured ranges of total foot eversion for all subj ects were smallest for the softest and about twice as large for the ha rdest insert construction. Thus, the soft insert construction was more restrictive, forcing all feet into a similar movement pattern, wherea s the harder combinations allowed for more individual variation of foo t and leg movement and did not force the foot into a preset movement p attern. The individual results showed substantial differences between subjects and a trend: Subjects who generally showed a reduction of tib ial rotation with all tested inserts typically had a flexible foot. Ho wever, subjects who generally showed an increase of tibial rotation ty pically had a stiff foot. Conclusions: The results of this study sugge st that subject specific factors such as static, dynamic, and neuro-ph ysiological characteristics of foot and leg are important to match spe cific feet and shoe inserts optimally.