ABSTRACT
Foot orthoses are widely prescribed to treat a range of lower extremity problems. Long-term biomechanical effects of foot orthosesare not clearly documented in the literature. The aim of this study was to examine long-term effects of foot orthoses on leg muscles activity in individuals with pesplanus during walking. In this clinical trial we selected 45 subjects after clinical examination. The subjects were divided into three equal groups: experimental pesplanus, control pesplanus and a healthy control group [with normal feet]. In the pre-test stage, electrical activity of leg muscles including tibialis anterior, peroneus longus, medial gastrocnemius and soleus were recorded at stance phase of walking, while all subjects walked barefoot along a 14m line. Experimental pesplanus group wore the custom-made orthoses for a period of six months. Then experimental pesplanus and control pesplanus groups underwent post-test. One-way ANOVA was used for data analysis. After six months of utilizing foot orthoses, the tibialis anterior activity significantly decreased in contact sub-phase [P=0.006]. The medial gastrocnemius activity showed a significant decrease in midstance sub-phase in the post-test [P=0.007]. Also, the soleus muscle had decreased activity in contact [P=0.033] and midstance [p=0.023] sub-phases in the post-test. According to the results of this study, we found that long term use of foot orthoses could change muscle activation and result in secondary adaptation