Effect of ankle brace on the activity and co-contraction of ankle muscles during single-leg landing

Abstract

Objectives: The results of a few studies about the effects of ankle brace on muscles function during the performance of different tasks are contradictory. Moreover, the effect of brace on the co-contraction of ankle muscles is undiscovered. Therefore, the present study investigated the effect of brace usage on the ankle muscles activity and co-contraction during single-leg landing. Methods: Fifteen non-athletic males aged 22.3±1.09 years without any traumatic injury and abnormality of the lower limb participated in this study. Electromyography activity of the ankle muscles (tibialis anterior, lateral gastrocnemius, medial gastrocnemius, peroneus longus and soleus) and muscle co-contraction in the anteroposterior and mediolateral directions were compared between two single-leg landing conditions, in respect of braced and unbraced ankle. The subjects landed from a 60-cm height bench. For the normalization of electromyography amplitudes, maximal voluntary isometric contractions were recorded for each muscle. Paired Samples t-test was used to compare muscle activities and co-contractions between the two conditions of landing. Results: In general, the activity of selected ankle muscles was reduced in braced condition, compared to the unbraced condition (P < 0.001). This reduction was not significant in the gastrocnemius lateralis muscle. In addition, the muscles co-contraction decreased in both directions during landing in braced condition (P < 0.05). Discussion: According to the obtained results, ankle brace reduces the activity and cocontraction of ankle joint muscles during landing. These findings can be considered as advantages of using brace, because it could reduce the load imposed on joint and muscles.