Effects of foot orthoses on the temporal pattern of muscular activity during walking

BackgroundSeveral studies have described the biomechanical effects of foot orthotics, as well as their effects at the level of muscular recruitment. Although the latter effect is unlikely to be limited to muscular intensity, the temporal pattern of activity of the muscles involved in walking with orthoses is still unclear.MethodsTwelve adults with everted static rearfoot posture higher than 5° of valgus participated in the study. For all participants, the kinematic data and the muscular temporal activity of the tibialis anterior, the soleus, the gastrocnemius medialis, the gastrocnemius lateralis and the peroneus longus were measured under two experimental conditions, walking with and without custom-made orthoses. Data were recorded and analyzed using a motion analysis and a surface EMG system.FindingsThe results showed that, when walking with insoles, the activity of the tibialis anterior, the soleus, the gastrocnemius medialis, the gastrocnemius lateralis and the peroneus longus is shorter than walking without orthoses. Furthermore, when walking with orthoses, the activity of the soleus and the gastrocnemius medialis is delayed.InterpretationOur study corroborates that the realignment of the calcaneus with the talus decreases the range of eversion and inversion of midfoot. Moreover, it reports noticeable modifications on the start time and the duration of the muscular activity of the tibialis anterior, soleus, gastrocnemii and peroneus longus while using foot orthoses.