Effects of two types of foot orthoses on lower limb muscle activity before and after a one-month period of wear

Abstract

The purpose of this study was to quantify the effects of two types of foot orthoses (FOs) on muscle activity during walking. Twenty-one healthy participants were recruited to walk on a five-meter walkway with a control condition (no FOs) and two experimental conditions (FOs and FOs with lateral bar). The experimental protocol was performed before and after a one-month period of wear for each experimental condition. Electromyographic signals were recorded for six muscles (gluteus medius, vastus lateralis, medial gastrocnemius, lateral gastrocnemius, peroneus longus and tibialis anterior). Mean muscle activity was analyzed during the contact, the combined midstance/terminal stance and the pre-swing phases of gait. Peak amplitude and time to peak amplitude were quantified during the stance phase. Unacceptable level of variability was observed between the testing sessions. Therefore, no comparisons were performed to compare the effects of the experimental conditions between testing sessions. After a one-month period of wear, FOs with lateral bar decreased peak amplitude and mean activity of the peroneus longus muscle during the combined midstance/terminal stance phase and FOs decreased peak amplitude and mean activity of the tibialis anterior muscle during the contact phase compared to a control condition. In conclusion, repeated-test design should be used with caution when assessing the muscular adaptation to the wear of FOs for a certain period of time. More studies are needed to determine if the decreased activity of the peroneus longus muscle could be of benefit to treat pathologies such as peroneal tendinopathy or lateral ankle instability.