Lower limb muscle activity during gait in individuals with hearing loss

The objective of this study was to investigate the electrical activity of lower limb muscles during gait in an able-bodied control group and in deaf individuals. Thirty male children were equally divided into a control group and a group of deaf children. A portable EMG system was used to record the activity of the bilateral tibialis anterior, gastrocnemius medialis and vastus lateralis muscles during barefoot walking with and without dual task. For EMG analysis, the average root mean square (RMS) values of the five trials were calculated and then normalized based on the peak RMS obtained by the maximum isometric voluntary contraction. MANOVA test was used for between group comparisons. The significance level was set at p < 0.05 for all analyses. The findings indicated that gait speed in children with hearing loss was smaller than that in control group. Dual task resulted in a decreased walking speed of children with hearing loss. The activities of tibialis anterior muscle in terminal stance phase (p = 0.040), medial gastrocnemius muscle in loading response and initial swing phases (p < 0.05), and vastus lateralis muscle in the terminal stance and pre swing phases (p < 0.05) were greater in deaf group. In deaf children the gait speed was reduced and the muscle activity was increased with respect to those in control group. This altered gait speed and muscle activity is suggestive of a lower mechanical efficiency of gait in deaf children.