Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 3 2 2017 8 1 Comparison of the Percentage Stance and Swing Phases and Ground Reaction Force between Young and Older Adults during Walking at different speeds 5 14 FA Neda Brooshak Department of Sport Biomechanics, Faculty of Sport Sciences, Mazandaran University, Babolsar, Iran Mousa Asadi Seyyed Hossein Hosseini Objective: comparing the effects of gait at different speeds on spatiotemporal and kinetic parameters can result in better perception of gait pattern differences between young and older adults. Thus the purpose of this study was to compare the percentage of gait stance and swing phases and vertical ground reaction force between young and older adults during walking with different speeds. Methods: 20 young and 20 older adult men with mean age of 25.73 and 66.54 years old respectively, were selected via nonrandom sampling. the percentage of stance and swing phases gait cycle and vertical ground reaction force (VGRF) in stance subphases including weight acceptance, midstance and push off during walking at a 10-meter pathway with slow, medium, and fast speeds, were measured by Kistler Force plate. The data were analyzed running ANOVA with repeated measures and Bonferronii tests. Results: The results showed that in both age groups, with increasing walking speed, the percent of stance phase would decrease and the percent of swing phase was increased (P<0.01), there was not a significant difference between two groups (P>0.05). Also, at slow speed, there was no significant difference in vertical ground reaction force between two age groups (p>0.05). But, there were significant differences in the VGRFs of weight acceptance and push off phases at medium and fast speeds, between two groups (p<0.01). In addition, there were significant differences at VGRFs of weight acceptance and push off phases between different speeds (p<0.01). Conclusion: In general, the percentage of stance and swing phases of a gait cycle is similar between young and older adults. Lower VGRFs of weight acceptance and push off phases in the elders reflects the weakness of the knee extensor, hip extensors and ankle plantar flexors. It seems that older adults reduce the rate of force production during fast gait to achieve the necessary capacity for power generation and thereby, overcome the weakness of the lower extremity muscles.

Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 3 2 2017 8 1 Effects of Proprioception Exercises in the Rehabilitation Process of Football Players after Arthroscopic Surgery Anterior Cruciate Ligament (ACL) 15 25 FA Manouchehr Haidary Department of Pathology and Corrective Exercises, Faculty of Physical Education and Sport Sciences, Razi University, Kermanshah, Iran.  Objective: The aim of this study was to test the effect of proprioception exercises in the rehabilitation process of football players after arthroscopic surgery on anterior cruciate ligament (ACL). Method: Data was collected from Specialist Hospital and Research Center in Rehabilitation, Medicine and Sports, Moscow, Russia. 20 patients with an average age of 16-25 years old with no historical records of neuromuscular diseases and injuries of the lower extremities. These were randomly divided into two groups: one experimental and one control. The experimental group were under monitoring for about five months, while they were doing proprioceptive exercises. Before and after the training period, the static equilibrium from the stork test and the dynamic performance of the star test were estimated and compared. Data were analyzed using Mann-Whitney and t-test with the significance threshold of (p<0.05). Results: through the proprioceptive exercise protocol, static and dynamic balance was significantly improved (p<0.001). Conclusion: This study confirmed that proprioception exercises classified from simple to complex according to sport fields in different phases of rehabilitation can positively affect the balance, the performance and quick return of football players to sports fields.

Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 3 2 2017 8 1 Principal Component Analysis Of Anthropometric and Biomechanical Variables In Adolescent Elite Karateka Athletes 27 41 FA Seyed Ehsan Naghibi Department of Sport Biomechanics, Shandiz Institute of Higher Education, Mashhad, Iran. Mehrdad Anbarian Mohammad yousefi Elham Shirzad Saeedeh Aziziyan Objective: Despite the importance of identifying people susceptible to sports, there is little documentation and studies related to karate talent identification.The purpose of this study was principal component analysis of anthropometric and biomechanical variables in adolescent elite karateka athletes. Methods: Subjects divided to adolescent elite karateka athletes (n = 19) and non-karateka athletes adolescent (n=20) by convenience sampling method. Besed on the previous literature, some  biomechanical and anthropometric variables including subcutaneous layeres, circumference and length of the limbs, limb velocity, agility, balance and strength of the limbs was selected and measured. The principal component analysis (PCA) was performed to reduce the number of variables and identify the principal component Analysis anthropometric and biomechanical variables. Results: The results of this study showed that the most important anthropometric and biomechanical variables of adolescent elite karate athletes were thoracic subcutaneous fat, height, Sarjent jumping, static balance, handgrip relative strength, chest circumference, ankle circumference, dynamic  balance, abdominal subcutaneous fat and apparent leg length. Conclusion: According to the results of the present study, the extracted anthropometric and biomechanical characteristics can be used for identifiying the talent karateka athletes.  

Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 3 2 2017 8 1 The Effect of Short-Term Use of Cold Spray on Strength and Ankle Joint Position Sense in Professional Wrestlers 43 50 FA Hamidreza Naserpour Department of Sports Biomechanics, Faculty of Physical Education and Sports Sciences, Kharazmi University, Tehran, Iran. Heydar Sadeghi Objective: The aim of this study was to investigate the effect of a short period of cryotherapy on strength and ankle position sense in professional wrestlers. Methods: In this semi experimental study, fourteen Professional wrestlers (age 24/2+3/5 years old, and weight 74/1+19/2 kg), all of whom had at least five years training experience with provincial and national championships participated in this study. Manual Muscle Tester was used to measure the strength of dorsi and plantar flexor muscle before and after cryotherapy that was simultaneously applied on medial-lateral of the ankle, with distance 30 cm. Meanwhile, performance accuracy of the ankle joint was assessed via Electrogoniometer that measures the active and passive regeneration error of ten and twenty angles of dorsi and plantar flexion respectively, before and after cold application. Shapiro-Wilk test was used to check the normality distribution, and a paired samples t- test was run to compare variables with a significant level of (p≤0.05). Results: The results showed that short-term local cooling by using cold spray does not significantly change the strength of dorsi and plantar flexor muscles and ankle joint position sense of professional wrestlers in active and passive form. Conclusion: Based on the results, it seems that applied cryotherapy only affects the skin receptors and it does not affect the body's protective factors, such as muscle spindle and Golgi organelles, and inner receptors that play a main role in the tension and joint position sense.

Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 3 2 2017 8 1 Investigation Stability of Upper Limb Function in Handballers with Glenohumeral Internal Rotation Deficit 51 59 FA Noorollah Javdaneh Department of Corrective Exercise and Sport Injury, Faculty of Physical Education, University of Kharazmi, Tehran, Iran. Amir Letafat kar Nazanin Kamrani Faraz Behnam Shokri Objective: Glenohumeral Internal Rotation Deficit is one of the important risk factors in throwing athletes that can cause adverse effects on glenohumeral joint biomechanics during throwing activity and overhead activity. Methods: In this descriptive study, 30 male student Hanballers (age=18 to 25 years) were categorized into healthy (n=15) and Glenohumeral Internal Rotation Deficit (n=15) groups. Upper quarter y balance test (YBT-UQ) was used for measuring functional instability of dominant shoulder. MANOVA test was run for comparing the performances of the two groups.  Results: In all directions, the stability of the shoulder in Hanballer with Glenohumeral Internal Rotation Deficit was significantly lower than that in the healthy group. Conclusion: Based on the results of this study, functional stability of the unstable shoulder of Hanballers with Glenohumeral Internal Rotation Deficit is lower than the functional stability of the healthy subjects; therefore, we suggest that the upper extremity stabilization exercises, specially the closed kinetic chain exercises be added to the shoulder rehabilitation programs.

Islamic Azad University, Hamedan Branch Journal of Sport Biomechanics 2476-4906 3 2 2017 8 1 The Effects of Shoulder- Girdle Muscles Fatigue on Ground Reaction Force, Elbow and Shoulder Joint Angle, and Accuracy of the Athletic Performance in Handball Penalty Throws 61 71 FA Mona Shiravand Department of Sport Biomechanics, Faculty of Physical Education and Sport Sciences, Islamic Azad University, Brojerd branch, Brojerd, Iran. Nader Farahpour Mahdi Majlesi Objective: Fatigue is an integral part of sports that can affect athletic performance. The aim of this study was to determine the effect of shoulder girdle muscle fatigue on ground reaction force, Elbow and shoulder angle, and accuracy in handball penalty throws. Methods: 10 healthy male handball player with no history of injury in the shoulder (mean age 9/18 years, weight 79/72 kg, height 179 cm, 6/5 year membership in the team) voluntarily participated in this study. The subjects with full respect for the laws took a total of 16 penalty shots before and 16shots after reaching fatigue. Ground reaction force, angle of elbow and shoulder, and accuracy of launch of the two phaseس (phase of preparation for throwing and phase of the release of the ball) were recorded before and after fatigue. Results: Results showed significant differences in ground reaction force and accuracy of the throws before and after fatigue (p<0.05), but significant differences were not observed in case of effect of elbow flexion and shoulder flexion and abduction (p>0.05). Discussion: As the subjects were professional, muscle fatigue did not have a significant effect on postural control, angles and angular velocity; but did affect the reaction force and accuracy of the throws before and after fatigue, which could ultimately affect the performance of athletes and competition results.