Individual effects on biomechanical variables during landing in tennis shoes with varying midsole density.

The aim of this study was to determine whether individuals responded uniquely to three different pairs of tennis shoes that differed only in midsole hardness. Kinematic and kinetic data were collected while the subjects (n = 3) performed a stereotyped lateral movement wearing each of the three pairs of tennis shoes. The results were analysed statistically for each subject separately. Variables were identified as discriminators between shoes for individual subjects based upon the results of separate discriminant analyses. After these analyses, a multivariate analysis of variance (MANOVA) was used for each subject to determine whether the discriminator variables differed significantly between shoes. A scoring system was devised that used the results of the MANOVA to assign scores to shoes for each variable. Cumulative scores for shoes (for each subject) were compared to determine which shoe was best for a subject. The results indicated that each subject responded uniquely to the shoes, and each demonstrated a preference for a particular pair of shoes. A need for single-subject designs exists when evaluating variations in athletic shoes.