Date of Award

Spring 5-1-2004

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Athletic Training

First Advisor

Mitchell L. Cordova

Second Advisor

Timothy J. Demchak

Third Advisor

Christopher D. Ingersoll

Abstract

Context: The effect of different types of athletic shoes, foot orthoses, and other arch support materials on lower extremity kinetics and ground reaction forces during walking and running gait has been documented; however, the potential effects of such devices on ground reaction forces during drop landings has not been extensively studied. Objective: The purpose of this study was to evaluate if over-the-counter orthotics, made of the same material, affect vertical and mediolateral ground reaction forces during a drop landing. Design and Setting: A lx3 repeated measures design guided this study where the independent variable, orthotic, has 3 levels (no orthotic-control, Spenco Insoles, Spenco Arch Cushions). The study was conducted in the Biomechanics Research Laboratory at Indiana State University. Subjects: Ten healthy males (age=25.1±3.3 yrs, height=l 79.2±7.3 cm, mass=85.9±20.1 kg) with no known lower extremity pathology 12 months prior to the study volunteered to participate. Each subject performed 5 trials of a drop landing from a 60 cm height onto a force platform under each condition. Measurements: The ground reaction force data were digitally converted at 1000 Hz, appropriately processed, and analyzed into the following variables: peak vertical ground reaction force (PVGRF), vertical impulse (VI), time to peak vertical ground reaction force (TPVGRF), and average mediolateral ground reaction force (MLGRF). Results: The arch support condition showed an increased PVGRF compared to the control condition (P<0.05), but no difference existed between the insole condition and the control or between the orthotic conditions. An increased TPVGRF was found for the arch support condition when compared to the insole condition (P<0.05), but no difference existed between the control condition and either orthotic condition. The arch support condition had an increased VI when compared to the insole condition (P<0.05), but no difference existed between the control and either orthotic condition. Orthotic conditions had no effect on MLGRF (P>0.05). Conclusions: The results of this study suggest that the selected orthotic devices used in this study may not be resilient enough to withstand the higher forces that are produced during a drop landing.

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