Muscle activation during fast walking with two types of foot orthoses in participants with cavus feet

The aim of this study was to quantify the effects of foot orthoses (FOs) with and without a lateral bar on muscle activity of participants with cavus feet. Fifteen participants were recruited from the Université du Québec à Trois-Rivières students and podiatry clinic. The muscle activity of the tibialis anterior, fibularis longus, gastrocnemius lateralis and medialis, vastus medialis and lateralis, biceps femoris and gluteus medius were recorded during fast walking under two experimental conditions (FOs with and without a lateral bar) and a control condition (shoes). Experimentations were completed after a one-month adaptation period to each experimental condition. The root mean square of the electromyography (EMG) data was analyzed. To compare the effects between conditions, a curve analysis was performed using one-dimensional statistical parametric mapping. The main result of this study was an increased gastrocnemius lateralis muscle activity (maximum mean difference: +28%) during the propulsion phase of gait (44-46%) when participants wore FOs compared to the control condition. This result will help researchers and clinicians better understand the FOs' EMG effects of individuals with cavus feet. As FOs are mainly prescribed for symptomatic patients, future studies should assess their effects on individuals suffering of a pathology, such as Achilles tendinopathy.