نشریه پژوهش در طب ورزشی و فناوری
پیاپی 17 (بهار و تابستان 1398)

Using appropriate devices and scientific methods can accelerate the process of sport talent identification and development to achieve championship level, and could also provide condition in which capable and talented athletes obtain highest level performance rapidly, so they will have long life championship. Former researches in scope of sport talent identification usually have been done in order to determine or normalize effective parameters. The purpose of this study was to design football talent identification algorithm based on fuzzy logic which classifies the football athletes. Due to expert opinion, essential parameters of football talent identification which also used in this software are; Cardio respiratory capacity (Physiology), Agility (Ability of motion), Dribble (technical skill) and Motivation (psychology). Norms of elite football player teenagers (14-16 yrs) are also used as index. Then with considering parameters and index, a fuzzy algorithm is designed which classifies football players in Unmatched, Semi-matched, Matched, Brilliant and Rare class. These results can help trainers and coaches in order to select talented and capable football players. In validation and reliability, records of elite junior Brazilian and Portuguese soccer have compared with norms of Iranian elite soccer.

The purpose of this research was to determine the acute effects of plyometric training with changing of height landing on the electromyographic activity during preparatory phase land-jump in male students. The population of this research were 10 physical education male students of Kharazmi University, which selected as sample. (21/10±1/286yrs, 173±6/467 height, 68/2±7/42 weight). In four different days subjects Performed as single leg one of four protocols plyometric training and land - jump from a height of 40 and 60 cm. EMG activity of the quadriceps and hamstring muscle group 150 milliseconds before foot contact with the ground was recorded. Analysis of variance with repeated measures and Bonferroni post hoc test was used. The results of this study showed that muscle activity after changing of height landing in preparatory phase (from 40 to 60 cm) has increased significantly (P=0/002, P=0/001, P=0/001) respectively. Activity of muscles (rectus femoris, vastus lateralis, biceps femoris) during landing after performing plyometric and changing of height landing in preparatory phase has increased significantly (P=0/039, P=0/001) (P=0/006, P=0/000) (P=0/001, P=0/014) respectively. Jump height has increased significantly (P=0/007, P=0/002) respectively. The results showed that acute perform plyometric training with changing of height landing result in significant changes in the electrical activity of muscles and also the height of the jump in the preparatory phase.

Although to improve balance and grasp the proprioception, recommended balance exercises, but there is not clear mechanism for the effectiveness of equilibrium training on healthy subjects. Suitable interaction of varios system of body and environment are necessary to maintain of the balance. Balance exercise is prescribed to improve balance and proprioception. There is not clear mechanism about the effectiveness of these exercise on healthy subjects. So The purpose of this study was to the Effect of 8 weeks of ankle-specific balance training on the balance and knee and ankle proprioception of adolescent volleyball players. the statistical sample of this study was 30 adolescent volleyball players in the league Golestan Which were selected as accessible and were randomly assigned into experimental and control groups. The experimental group performed 8 weeks and 3 sessions per week of ankle-specific balance. The results showed that there was a significant difference in the mean of balance and errors in reconstructing the angles of knee and ankle after exercise in the experimental group, while in the control group it was not significant. Results of this study showed that Balance Training can improve balance and proprioception in the knee and the ankle.

Nowadays there is no specific and effective standard for evaluating the helmets in martial arts which it has caused a lot of brain damages. The purpose of this study was designing and modeling a helmet assessment machine in martial arts, based on dynamic’s parameters and criteria. SolidWorks, Adams and Catia softwares were used for designing this machine. Also, In order to build this machine, an artificial head that equipped with force and acceleration sensors and a mechanical arm for applying impact to the head were used. The validation of the machine was done by comparing its results (impact force, linear acceleration and rotational acceleration) with the results obtained from the simulated model in the computer. The Pearson correlation coefficient of 0.9 that obtained from this comparison indicates that the results of this machine are correct. To confirm the reliability of the machine, an Intraclass Correlations was used, the results showed values of 0.7 and greater than that and it also confirmed the appropriate repeatability of the machine. According to the results of this study, due to the considering the important parameters of linear and rotational acceleration and the impact force in evaluating helmets and investigating the mechanism of head injury in the conditions close to competition ones, the device can be an appropriate equipment for more accurate measurement of helmets in martial arts.

Balance is a complex concept, especially when one wants to do complex motor skills. Therefore, the balance during activity is more important than the static and dynamic balance that is performed without the skill. The aim of this study was to introduce a new activity-based balance index of elite soccer players. 27 young soccer players (12-14 years) whom participated in Iranian premier league were selected. To assess their balance, activity and skill, four functional tests consisting one leg stance, dynamic Y balance, running and dribbling tests were administered. During these tests, besides their relative scores, the acceleration of body center was also recorded using an accelerometer and a new activity-based balance index (ABI) were calculated from these available data. The Results showed a significant positive correlation between ABI and both static and dynamic balance scores(r=0.6, p=0.002). Also, a significant negative correlation was found between ABI and dribbling scores(r=-0.45, p=0.026), which could be interpreted as the necessity of agility of the players. It could be concluded that this new activity-based balance index was found to be successful for evaluating both the balance and the skill level of soccer players.

Osteoporosis is characterized by low bone mineral density resulting into an increased risk of fracture (9). The aim of the study is determine the effect of aerobic exercise with blood flow restriction (BFR) and vitamin D supplementation on ostosis metabolic markers (OMM) among middle aged females. In this study 30 females with age of 42.76±7.44, height of 157.90±5.74, weight of 70.55±9.68 and BMI of 28.33±3.87, divided in three groups of 10 subjects, randomly. Two empirical Groups with and without BFR, both with vitamin D supplementation, one hour before training, performed aerobic exercise during eight weeks, three days a week, one hour a day, with 50 - 70% intensity of maximal heart rate. Density of OMM, calcium, phosphorous and alkaline phosphate examined in lab, 48 hours before and after training period in saving status before breakfast. Aerobic power of empirical groups determined with 12 minutes run/ walking cooper test. For data analysis used descriptive statistics, ANOVA and analysis variance with repeated measures. Results showed that eight weeks exercise with BFR and vitamin D supplementation, the density of calcium and phosphorous increased significantly. The density of Alkaline - phosphate did not show variation significantly. In the other hand, only the rate of calcium showed variation significantly, which increased in without BFR more than others. In conclusion, aerobic exercise with and without BFR and vitamin D supplementation can increase the density of OMM, calcium, phosphorous and alkaline- phosphate. But only the density of calcium showed increasing significantly.

The aim of this study was to investigate the effect of muscle soreness due to the plyometric exercises on leg muscle EMG activity after concentric and eccentric contractions in untrained people. 20 students from untrained male students (at least 6 months out of practice), were randomly assigned to experimental (n=10) and control (n=10) groups. At  pre-test, surface electromyographic activity of gastrocnemius muscle were recorded using by the Biovision 18 channel device during the both concentric (squat / plantar flexion of the ankle) and eccentric (wirepuller / ankle dorsiflexion) contractions. Then, in order to build muscle soreness, experimental group exerted 10 minutes selected plyometric exercises, while the control group did not have any training. Finally, immediately after protocol training and also after 48 hours the same record was done. Data were analyzed by Dasylab and Matlab software, and the ANOVA Repeated Measure and Bonferroni post hoc also were used for statistical analysis at a significance level of P≤0/05. The results showed that fatigue resulting from plyometric exercises, could have significant reduction in activity of gastrocnemius muscle immediately and 48 hours after exercise during eccentric contraction (P=0/001), while it was not true for concentric. According to the results, the risk of eccentric contraction could be considered for untrained people during training.

Considering the important role of the scapula in the glenohumeral joint movements, its position on the thorax can affect the function of the joint. Therefore, the purpose of this study was to investigate the predictive relationship of the strength and glenohumeral rotation range of motion (ROM) with scapular dyskinesis (SD) in female athletes with overhead-throwing pattern. The present study was a descriptive-correlational research on 60 athletic female in volleyball, handball, basketball and badminton. The Lateral scapular slide test was used to examine SD. the dynamometer and goniometer were used to measure the strength and glenohumeral rotation ROM respectively. Data were analyzed using Spearman correlation and multiple regression tests. The correlation coefficients between SD and the glenohumeral internal rotation ROM (r=-0.734; p=0.000), the glenohumeral external rotation ROM (r=0.693; p=0.001), the glenohumeral internal rotation strength (r=0.674; p=0.005) and the glenohumeral external rotation strength (r=-0.719; p=0.001) were significant. Analysis of the research model showed that about one-third (30.1%) of total changes in SD were dependent on the independent variables mentioned in this regression model. therefore, screening of  athletes with overhead-throwing pattern must be taken into consideration in order to recognize SD, and participate in corrective exercises to increase the glenohumeral internal rotation ROM and the glenohumeral external rotator muscles strength.