TEffect of Fatigue on frequency spectrum of muscles and forces on the foot while running in patients with pronated Feet

Abstract Introduction: Pronated foot, as one of the common foot deformities, can affect the biomechanics of running and risk of lower extremity injury. Fatigue, as a result of doing heavy tasks, can also change biomechanical parameters of locomotion. Under the fatigue conditions, the biomechanical differences individuals with pronated feet are more easily identified. Thus, the main objective of the present study was to examine the effects of Effect of Fatigue at Shoes with Spikes Containing Two different stiffness on frequency spectrum of muscles and forces on the foot while running in patients with pronated Feet. Methods: According to the subject and objectives of the research, the method used in this research was quasi-experimental and laboratory. A statistical sample of ۲۲ people aged ۲۰-۳۰years was selected by purposive sampling and participated in the present study. Statistical samples were divided into two groups. There were ۱۱ young men with pronated feet group and ۱۱ young women with pronated feet group. The navicular bone sagging method was used to divide the pronated group. Using the Bertak force plate with dimensions (۶۰ × ۴۰ cm۲), the ground reaction forces in the vertical (Fz), anterior-posterior (Fy) and internal-external (Fx) directions when running. An electromyography system made in England was used to record the electrical activity of the muscles. Electromyographic activities of the selected muscles before and after fatigue protocol were recorded. The statistical analysis was performed using the SPSS software and running ANOVA (p≤۰.۰۵). Results: The results showed that the free torque peak component and the support time component during running on the Shoes with Spikes Containing Two different stiffness increased compared to the control Shoes. Also, when the heel hits the ground, the internal-external component during running on the Shoes with Spikes Containing Two different stiffness has decreased compared to the control Shoes. In addition, at the moment when the heel separates from the ground in the internal-external component, the moment the heel hits the ground in the vertical component and the time to reach the peak of the vertical component, the reaction force of the ground during running on Shoes with Spikes Containing Two different stiffness decreased compared to the control Shoes (P<۰.۰۵).on the other hand, Results demonstrated significant shoes, fatigue-by-group interactions was found for biceps femoris muscle activity at before heel contact phase, Furthermore, significant shoes, fatigue and group interactions was found for vastus medialis muscle activity at after heel contact phase (p<۰.۰۵) on the other, Findings showed significant main effect of fatigue-by-shoes interactions for vastus lateralis (p=۰.۰۲۱) muscle activity at after heel contact phase during running. on the other hand, the result showed that tibialis anterior muscle activity at after heel contact phase was significantly (p=۰.۰۱۷). Conclusion: The results showed that the use of Shoes with Spikes Containing Two Different Stiffness can improve the risk factors for injury in people with pronates.

Keywords:

Electromyography , ground reaction forces , Running , Pronated feet , Fatigue