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Mario A. Lafortune

Miniature pressure sensors and high-speed video were used to assess the lateral support and stability of court footwear during in vivo performance of lateral side-stepping moves. Two distinct types of court footwear construction were evaluated and were found to differ by approximately 100% and 200% in lateral support and stability, respectively. The heel control index that combined both parameters revealed differences exceeding 425%. A comparison of shoes that differed only in one construction feature produced similar trends. These overall results suggest that the combined high-speed video/pressure approach allows high discrimination of footwear rearfoot control properties during in vivo simulated playing conditions. The specific experimental results suggest that footwear designed for court sports exhibits considerable differences in foot support and stability. Furthermore, it was found that some construction features could improve these properties in court footwear.

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Ewald M. Hennig and Mario A. Lafortune

Using data from six male subjects, this study compared ground reaction force and tibial acceleration parameters for running. A bone-mounted triaxial accelerometer and a force platform were employed for data collection. Low peak values were found for the axial acceleration, and a time shift toward the occurrence of the first peak in the vertical force data was present. The time to peak axial acceleration differed significantly from the time to the first force peak, and the peak values of force and acceleration demonstrated only a moderate correlation. However, a high negative correlation was found for the comparison of the peak axial acceleration with the time to peak vertical force. Employing a multiple regression analysis, the peak tibial acceleration could be well estimated using vertical force loading rate and peak horizontal ground reaction force as predictors.

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Ewald M. Hennig, Thomas L. Milani, and Mario A. Lafortune

Ground reaction force data and tibial accelerations from a skin-mounted transducer were collected during rearfoot running at 3.3 m/s across a force platform. Five repetitive trials from 27 subjects in each of 19 different footwear conditions were evaluated. Ground reaction force as well as tibial acceleration parameters were found to be useful for the evaluation of the cushioning properties of different athletic footwear. The good prediction of tibial accelerations by the maximum vertical force rate toward the initial force peak (r 2 = .95) suggests that the use of a force platform is sufficient for the estimation of shock-absorbing properties of sport shoes. If an even higher prediction accuracy is required a regression equation with two variables (maximum force rate, median power frequency) may be used (r 2 = .97). To evaluate the influence of footwear on the shock traveling through the body, a good prediction of peak tibial accelerations can be achieved from force platform measurements.