چكيده لاتين
Centeral nervous system controls muscules activity in small blocks and muscular synergies due to movement conduction reduced degrees of freedom. Walking is of movements which follows synergistic control. Vision is one of factors affecting walking mechanics is. So that, blind individuals exhibit different walking mechanics. Effects of lack of vision on synergistics control of muscles during walking is not well known. The aim of this study was to investigate non-negative matrix factorization algorhythm to extract muscular synergies recruited by nervous system specifically focusing on blind individuals while walking. Eight blind and eight normal adolescent boys participated in this study. Tibialis anterior, peroneus longus, gastrocnemius medialis, soleus, vastus medialis, vastus lateralis, biceps femoris, semi tendinosous, gluteus medius and gluteus maximus emg activity was recorded in self-selected walking speed. Electrodes were placed according to recommendations of electrode placement from european SENIAM protocol. Data were rectified and low pass filtered with a 4th order 6Hz filter to create linear-envelops. Then, data were time normalized. Non-negative matrix factorization algorhythm was used to extract muscular synergies. In determining number of sufficient number of synergies, VAF is necessary. So, Variance account for (VAF) was used to find sufficient number of synergies to reconstruct original data in the groups. To assess similarity of activation patterns in the synergies, pearson correlation coefficient was used, and independent t-test was used to compare relative weights of muscles in the synergies between the groups. The results showed that in blind group, three synergies is sufficient to reconstruct origional data, while, able-bodied individuals five synergies are sufficient to reconstruct origional data. Also, the results showed that there is low to moderate similarity between activation patterns of the synergies between the groups. According to the results of the current study, it can be concluded that blind individuals use lesser synergies to control muscular activity in walking. This lesser synergies seems to be due to simplifying walking motor control in blind individuals.
