درخت حوزه‌های تخصصی

Introduction: Nowadays, the use of artificial turf fields has become widespread. Given the high prevalence of noncontact injuries among female soccer players and high contribution of the Anterior Cruciate Ligament (ACL) injury, this research was conducted to compare biomechanical risk factors in the incidence of ACL injury for elite female soccer players during shearing maneuver and header on the natural grass and artificial turf fields. Methods: Sixteen players were selected from U-14 women’s national team by the convenience sampling method and started to perform the skills. Knee joint information was calculated by a 3D imaging system and a force plate. Statistical differences were reported using the dependent t-test at a significant level of 0.05. Results: The findings showed that the biomechanical behavior of the lower extremity while performing soccer skills on the natural grass was affected differently from that on the artificial turf. Results also demonstrated that the torque applied to the knee joint on the natural grass was higher than that on the artificial turf (P=0.039). Angular velocity on the artificial turf was also higher than that on the natural grass (P=0.006). Conclusion: The higher knee joint torque and the lower angular velocity on natural grass may result in a higher risk of ACL injury on the natural grass than on the artificial turf. Therefore, the use of prevention programs for ACL injury is crucial to minimize the incidence of lower extremity injuries.

Present research is considered applied-developmental in its objective and qualitative concerning the research nature of data, and the research design was the interpretative structural model (ISM). In order to gather data, semi-structured in-depth interviews with experts in the consumer behavior domain, selected by theoretical sampling, have been utilized. The statistical population includes all sports managers, sports specialists, and fans, and sampling continued until theoretical sufficiency was achieved. After research completion, results were sent to two participants, and their opinions were approved by identifying indices related to football fans' superstitious behavior to draw the interpretative- structural model of factors influencing football fans' superstitious behavior. The result indicated the level of dependence and influence power of each index according to which individual characteristics and environmental conditions in the region under the influence include inculcation index in the autonomous region (independent) and indices of relief, the transmission of evil, coercion, and deterrence in the dependent region.

Purpose: The present study was done to specify the impacts of a protocol called “living high, training low and high (LHTLH)”on serum ET-1 and EPO levels as well as the 3000-m performance of endurance runners in Iran’s national team. Method: eight male runners (aged24.4±3.1, height of 180.5±4.2, weight of66.7±3.4 and BMI of20.1±5.0kg/m2) who cooperated voluntarily with regard to middle distance and marathon running (R2M system training) at high and low altitudes. All case studies did 3000-m test and blood samples were taken at a time period of 24-hours before and after the test. The intended tasks consisted of continuous, interval, aerobic and resistance exercises. The runners were to take part in 16 training sessions each week. It should be noted that the training lasted for 11 weeks according to (LHTLH) protocol. Variance with repeated measures (P≤0.05) was utilized as the method to analyze the collected data. Results: It was shown that 3000-m time underwent significant decrease with regard to the time of impact both before and after the training. However, there were not significant changes in EPO (P≥0.05). On the contrary the amount of ET-1 demonstrated significant increase (P≤0.05). Conclusions: The results indicated that 3000-m time at lower altitudes will decrease on account of certain training programs. The reason is not directly related to the level of EPO. It is through hematological and metabolic changes as well as increase of ET-1 levels that performance under hypoxic and normoxic states happens to improve in the real sense.