The Effecte of foot orthosis on electromyographic activity of ankle muscles in athletes with flat foot during single leg jump landing

Flat foot transfers a chain effect on the joints and upper segments and leads to disruption of kinetic chain.. Researches suggest that the use of foot orthoses may change muscle activation patterns of people with flat foot during walking and running activities to people with normal-arched feet but to date there are not studies on the effect of foot orthoses in neuromuscular control of athletes with flat foot deformity in sport tasks. The aim of this study was to compare EMG activity of muscles around the ankle joint in athletes with flat foot in the foot orthoses compared to the situation without foot orthoses, while single-leg jump-landing task is done. In this study of 15 athletes with flat foot deformity 18 to 23 years were selected purposively as the sample. EMG activity of four muscles (tibialis anterior, peroneus longus, medial gastrocnemius and soleus) during single leg jump-landing was registered in two situation with and without foot orthoses. The results showed significant differences in the feedforward activity of the tibialis anterior muscle (p = 0/002) and peroneus longus (p = 0/045) and in the feedback activity of the tibialis anterior muscle (p = 0/049), peroneus longus (p = 0/042), medial gastrocnemius (p = 0/015) and soleus (p = 0/005) between tow situations with and without the foot orthoses. Foot orthoses with changes in neuromuscular function of tibialis anterior, peroneus longus, medial gastrocnemius and soleus muscles may reduce the risk of injuries and disorders of the kinetic chain.