Influence of Different Sole Thickness on Biomechanical Parameters of Human lower Extremity

<p> <p id="x-x-O2-2693-2"> <strong> BACKGROUND </strong> : Different athletic shoe outsole thickness can influence human movement from the aspects of both performance enhancement and injury prevention. <p id="x-x-O2-2693-3"> <strong> PURPOSE </strong> : To investigate the influence of different outsole thickness on lower extremity muscle activity, kinematics, and kinetics during walking and running. <p id="x-x-O2-2693-4"> <strong> METHOD </strong> : Twelve male college students (age: 20.9&plusmn;0.7, height: 172.0&plusmn;2.1cm, body mass: 63.0&plusmn;3.4 kg) were tested. Four sole thickness (original commercial shoe, 1, 2, and 3 cm increased outsole thickness) were tested. Elastic modulus was tested using a universal testing machine (Instron-5544, US). The running tests were performed on a treadmill with a fixed speed (3.33 m/s) and continued for 8min. Walking tests were performed on a force platform (AMTI, US, 400&times;600mm). A motion capture system (VICON, Oxford, UK) was used to obtain kinematic data. Wireless surface electromyography testing system (Noraxon, US) was used to obtain the surface electromyography (sEMG) data. One- way analysis of variance with repeat measures (ANOVA) was used to compare differences in muscle activity, kinematic, and kinetic outcome variables. Statistical significance was set at &alpha; = 0.05. <p id="x-x-O2-2693-5"> <strong> RESULTS </strong> : The 1 cm sole thickness has the highest elastic modulus (0.80MPa) and the 3cm is the lowest (0.25MPa). The co-contraction index value of 1cm group was significantly less than the others in both initial (0.55&plusmn;0.14, P&lt;0.05) and final (0.53&plusmn;0.13, P&lt;0.05) stage of running. At the toe off, the knee angle of 2 cm (131.0&plusmn;9.5 deg, P&lt;0.05) and 3 cm (132.7&plusmn;4.6 deg, P&lt;0.05) group increased significantly comparing to 0cm (125.0&plusmn;5.4 deg) group in walking test. <p id="x-x-O2-2693-6"> <strong> CONCLUSION </strong> : The outsole thickness of 1cm reduced muscle co-contraction during running. Knee joint increased with the increasing of sole thickness at the time of toe off when walking. </p> </p> </p> </p> </p></p>