No abstract

No abstract

No abstract

No abstract

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.

This study evaluates the effect of dual tasks on balance during manipulation of visual information, the base of support, and cognitive tasks in 7–12-year-old children and adults. An equal number of girls (210) and boys (210) were selected from the schools by the cluster random sampling method (within the 7–12 age groups). Twenty young adults were also selected. Postural sway (PS) was measured in the anterior–posterior (AP) and mediolateral (ML) directions using a force plate in eight standing positions, including standing with closed eyes versus standing with open eyes and standing with feet together versus on a single limb, under the interference of cognitive dual tasks (DT) or a single task (ST). PS was found to decrease with advancing age. PS was also greater in men than women in both AP and ML directions (p < 0.05). PS was greater in the 7–12-year-old participants compared to adults under the manipulation of the base of support (p < 0.05). However, PS increased in all participants regardless of their age while manipulating both the base of support and visual information (p < 0.05). Children (within the 9–12 years age range) and adults could keep their balance while performing basic tasks; however, children had difficulty in maintaining their balance with higher task demands.

The evaluation of cognitive and motor performance can lead to a recognition of the risk factors associated with falling. The aim of this study was to compare cognitive and motor functions in elderly with and without experience of falling. In so doing, 60 elderly with and without falling experience voluntarily participated in this study. Mini Mental examination Test, working memory capacity test, reaction time, inhibition test, Berg balance test, tandem balance test, 6-minute walking test and balance confidence test were all administered to the groups. To analyze the data thus obtained, and to examine the relationship between the variables for estimated fall, independent samples t-test and regression analysis were run. The significance level was considered as p<0.05. The results showed that elderly people with fall experience had a weaker cognitive and balance-maintenance performance than those without such experience (p<0.05). The results of correlation and regression analyses indicated that Berg balance test, tandem, inhibition and MMSE had the strongest relationship with falling. Based on these results, it can be claimed that fall in elderly is associated with poor balance as well as cognitive decline. Age is one of the predictors of falling, and about 25% of motor activities are related to cognitive capacities.

The aim of this study was to evaluate the biomechanics of jumping and landing in defense between beginner and professional volleyball players. 10 professional volleyball players from Iranian leagues and 10 beginners with less than 2 years of training experience participated in this study. Selected kinetic and kinematic variables in jump and landing movement in 5 tasks of volleyball defense was analyzed. There were no significant differences between beginners and professional groups in different types of jumping and landing in the phase of preparation, jumping and landing in the variables of ground reaction force in different directions except the variable YP1 in the side stepping to the left (P = 0.029) and loading rate. The results also showed that the knee flexion angle at the moment of landing in all jumps was significantly higher in professional volleyball players than in the beginner group. The difference between the groups in maximum knee flexion in the landing phase was also significant in all jumps except the side stepping to the left (p <0.05) ). Professional volleyball players have a lower risk of ACL injury than beginner volleyball players. As a result, to reduce the risk of ACL injury in beginners, it is necessary to pay attention to landing exercises and focus on increasing the flexion angle.