Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 2 2 2016 8 1 Muscles Activity in the elderly with Balance Impairments in walking under Dual tasks 5 15 FA Elaheh Azadian Hamidreza Taheri Torbati Department of Motor Behavior, Faculty of Physical Education and Sport Sciences, Ferdowsi University of Mashhad, Mashhad, Iran. Alireza saberi Kakhki Objectives: Each step during gait requires different attention demands that will affect muscles activity. The study of changes in the timing and intensity of the muscles activity in walking with dual task has received less attention from researchers. The purpose of this study was to evaluate changes in electromyography patterns of gait with cognitive dual tasks in balance impaired elderly. Methods: Thirty older adults were recruited for this study. People were selected through berg balance test. Subjects walked 12-meters in two conditions, normal walking and walking with a cognitive dual task. Spatial-temporal kinematic parameters were recorded through the motion analysis and muscles activities were recorded through electromyography system. The data obtained was analyzed using repeated measures ANOVA at a significant level of p< 0.05.  Results: The results showed that walking under dual tasks would decrease gait speed and increase stride time and stance time. Also muscle activity in Tibialis anterior and Vastus lateralis in stance-phase would decrease significantly in dual tasks as compared with single task (p< 0.05), but timing of muscle activity would not change in dual task conditions.  Conclusions: Based on the results, it can be argued that walking under a dual task can change spatial-temporal parameters and muscle activity in gait pattern in the elderly with balance impairment. One explanation could be that the decreased control of the central nervous system on muscle activity in stance phase due to the performing of a dual task.

Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 2 2 2016 8 1 Comparison of Plantar Pressure Distribution in Dominant & Non-dominant leg of female Kata and Kumite National Team 17 30 FA Elnaz Dizaji Department of Sport Biomechanics, Faculty of physical education and sport sciences, Kharazmi University, Tehran, Iran Raghad Memar Heydar Sadeghi Objective: The aim of this study was to compare the plantar pressure distribution of dominant and non-dominant legs of females who were participated in the kata and kumite national team. Methods: Twelve kumite and 8 kata female athletes of the Karate national team participated in this study. Plantar pressure was measured using emed platform during barefoot walking. After dividing the foot into 10 masks, peak pressure, pressure-time integral, maximum force and force-time integral were calculated. Wilcoxon and U-Mann-Witney tests were used to analyze parameters at a significance level of p ≤ 0.05. Results: In comparison of kata and kumite teams it was found that, kata plantar pressure parameters in Metatarsal-2 (p=0.05) and Metatarsals-3, 4, 5 (p=0.04) were significantly less than those in kumite. Also, in comparison of dominant and non-dominant leg, plantar pressure parameters of dominant leg were less in Metatarsal-2 (p=0.04) and more in Bigtoe (p=0.04) and Toes-3, 4, 5 (p=0.03) than those in the non-dominant leg. Conclusion: Results may be indicative different of natures of the two athletic fields in that Kumite has a higher impact on plantar pressure due to higher mechanical loads. Furthermore, the unequal use of the legs may affect plantar pressure because of leg dominance. Thus, further and more comprehensive studies are necessary to prevent exercise-induced adaptations in professional levels and their treatments.

Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 2 2 2016 8 1 The Comparison of two models of marker – placement for identifying the rear foot angle in normal people with and without shoes during the stance phase of walking 31 41 FA Department of physical education and sport science, Faculty of physical education and sport sciences, Birjand, University, Birjand, Iran. Objective: The purpose of this study was to compare the two models of marker placement for identifying of rear foot angle in normal people with and without shoes during the different stage of stance phase of walking. Methods: Fifteen male students in Birjand University were selected based on Navicular Drop Index. After marker placement based on Clarke and Nigg models, the rear foot angle were recorded with two-dimensional analysis (Panasonic Camera) from behind position while subjects walked with 1.7 m/s on a treadmill with and without shoes. For statistical analysis, independent samples t-test was used (p≤0.05). Results: The Results showed a significant difference in rear foot angle during the stance phase between the two models of Clarke and Nigg during walking with and without shoes (p≤0.001). Conclusion: Based on the results of the present study, due to their specific features care must be considered when using any of these two models to investigate the angular kinematics of the foot.

Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 2 2 2016 8 1 Effects of 8 Weeks of Resistance Training with Traband on Dynamic Balance in Young Soccer Players 43 53 FA mahmoud khodabakhshi Department of Corrective Excercises and Sports Pathology, Faculty of physical education and sport sciences Ferdowsi University , Mashhad, Iran. Sayyed Aliakbar Hashemi Javaheri ahmad Ebrahimi Atri majid Ebadi Fara Objective: Keeping one's balance is a basic part of daily activities and it is an important factor in the performance of the athletic. The goal of this study was to study the effect of resistive exercises on young soccer players dynamic balance. Methods: Forty young soccer players voluntarily participated in this study and were randomly divided randomly into two groups of experimental and control. Subjects' dynamic balance in pre-test and post-test was measured using Biodex balance system. Experimental Group took part in an eight-week designed program of resistive exercises. Results: The average age (18.22±0.83 year), height (173±5.73 cm), Weight (62.1±6.88) were measured and independent sample t-test were run to compere the data collected in the pre-test and posttest. To see if there were meaningful differences in the performance of the groups following the training. The result indicated positive effect of the training of the overall balance (p= 0/001), lateral (p=0/001) and anterior-posterior (p=0/001) balance in the experimental groups. Conclusion: Results confirmed the significant influence of these exercises on subjects’ dynamic balance. Based on the results, using resistive exercises can be recommended in order to improve athletes’ dynamic balance.

Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 2 2 2016 8 1 Investigating Knee Alignment and Foot Structure in Futsal Players with and without Hamstring Shortness 55 63 FA Homan Minoonejad Reza Manteghi Ehsan Tasoujian Department of Sports Injury and Corrective Exercises, Faculty of Physical Education and Sport Sciences, Kharazmi University of Tehran, Tehran, Iran. Hossein Amiri Objective: The purpose of this study was to investigate knee alignment and foot structure in futsal players with and without hamstring shortness. Methods: In this descriptive - comparative study, 30 men athlete (18- 25 years) were recruited. They were assigned into two groups of 15 subjects with and without hamstring shortness. The hamstring shortness, knee and foot alignment were respectively measured by the goniometer, the ruler and caliper. After checking the normality of the data, (with Shapiro-Wilk test) independent samples t-test, were used to analyze of data at a significance level of P < 0.05. Results: The findings indicate that there is a significant difference between the navicular drop in both groups, with and without hamstring shortness with the difference being lower in athletes with hamstring shortness (P= 0.002); but there is not any significant difference between the distances between Femur Condylar in both groups (P> 0.05). Conclusion: It seems that, navicular drop is not common among athletes with hamstring shortness.

Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 2 2 2016 8 1 Determining the Optimum Training Conditions for Selective Strengthening of Vastus Medialis Oblique Muscle over Vastus Lateralis through Using Musculoskeletal Modeling 65 76 FA Farzam Farahmand Seyyed Hosein Hoseini Department of Sport Biomechanics, Faculty of Physical education & Sport Sciences, University of Guilan, Rasht, Iran Mohamad Mahdi Seifi Objective: The purpose of this study is to find the optimum training conditions for selective strengthening of the vastus medialis oblique muscle over vastus lateralis. Methods: For this purpose, a musculoskeletal model of lower limb was developed by OpenSim software. Using a detailed tibiofemoral and patellofemoral joint modeling and six muscular branches for components of quadriceps femoris muscle on the other hand, training conditions were simulated in isometric, isokinetic and isotonic modes. For each training condition, the motion kinematic and external force was applied to the model. After analyzing the inverse dynamics, the force of each component of quadriceps femoris muscle was obtained through the statical optimization. Impact of knee angle, speed of movement, external loading level and axial tibial rotation on activity rate of vastus medialis oblique to vastus lateralis muscle was investigated based on the model. Results: The results showed that the knee angle affect on this ratio and the highest ratio could be obtained in angles close to full extension of knee. Speed of movement and external load level would not affect the ratio. Meanwhile axial tibial rotation could affect this ratio in a way that increasing tibial external rotation was associated with increasing the ratio. Conclusion: The results indicate that high-speed isokinetic training with highest levels of tibial external rotation in angles close to full extension of knee can resulte in increasing the maximum activity ratio of vastus medialis oblique to vastus lateralis muscle.