The purpose of this study was to investigate the effects of ply metric trainings on LEGS EXPLOSIVE POWER, velocity, agility and flexibility in taekwondo players. The subjects of this study were20 taekwondo players in Mashhad (18-23 years) who participated voluntarily in this study. Before doing of ply metric exercises, for each dependent variable, a pretest was taken from the participants. Then, the subjects were divided randomly into two experimental and controlled groups. The experimental group were performed selected plyometric exercises for a period of 6 weeks, 3 session per week. Controlled group merely performed general taekwondo exercises. After doing of selected plyometric exercises, post tests were taken from both groups of study, again. Descriptive statistics was used to measure the averages and the standard deviation, kolmogrov- smerenov test for normality. In inferential statistics, t-test was used to compare averages of two groups in P£0.05 level, and Pearson coefficient of correlation was used to evaluate the relations among variables. Results: The results of the study indicated that plyometric exercises had significant effects on variables LEGS EXPLOSIVE POWER, velocity, agility and flexibility in taekwondo players.Conclusions: Studying the results of this study indicates that factors such as neuromuscular coordination, electro-reflexive activity improvement, enhancement of speed contraction and application of motor neurons, probably had influences in improvement of LEGS EXPLOSIVE POWER, velocity, agility and flexibility in taekwondo players.

In this paper, a novel risk-based, two-objective (technical and economical) optimal reactive POWER dispatch method in a wind-integrated POWER system is proposed which is more consistent with operational criteria.  The technical objective includes the minimization of the new voltage instability risk index. The economical objective includes cost minimization of reactive POWER generation and active POWER loss. The proposed voltage instability risk employs a hybrid possibilistic (Delphi-Fuzzy)-probabilistic approach that takes into consideration the operator’s experience, the wind speed and demand forecast uncertainties when quantifying the risk index. The decision variables are the reactive POWER resources of the system. To solve the problem, the modified multi-objective particle swarm optimization algorithm with sine and cosine acceleration coefficients is utilized. The method is implemented on the modified IEEE 30-bus system. The proposed method is compared with those in the previously published literature, and the results confirm that the proposed risk index is better at estimating the voltage instability risk of the system, especially in cases with severe impact and low probability. In addition, according to the simulation results compared to typical security-based planning, the proposed risk-based planning may increase the security and economy of the system due to better utilization of system resources.

Objective: The objective of this study was to explore the role of plyometric training in enhancing EXPLOSIVE POWER among sprinters. Methods and Materials: This qualitative research employed semi-structured interviews to gather data from 17 sprinters aged 18 to 30 years, with at least three years of competitive experience. Participants were recruited from local athletic clubs and universities. Data collectioncontinued until theoretical saturation was achieved, ensuring a comprehensive understanding of the impact of plyometric training. Thematic analysis was used to identify and analyze patterns within the data, providing detailed insights into the participants' experiences and perceptions. Findings: The study revealed significant physical improvements attributed to plyometric training, including enhanced muscle strength, increased speed, improved jumping ability, and reduced injury risk. Psychological benefits such as increased confidence, enhanced motivation, and improved mental resilience were also noted. Participants reported a better training experience with diverse and efficient routines, improved technique understanding, and strong peer support. Performance outcomes showed notable improvements in competition results, skill application, and recovery times. These findings align with existing literature, confirming the comprehensive benefits of plyometric training for sprinters. Conclusion: Plyometric training significantly enhances EXPLOSIVE POWER and overall performance in sprinters. The physical, psychological, and performance-related benefits make it a crucial component of athletic training programs. Despite limitations such as the small sample size and reliance on self-reported data, the study provides valuable insights into the multifaceted advantages of plyometric exercises.

Oxidative stress is one of the causes of fatigue and decreasing performance in athletes. Epidemiological studies have shown that antioxidant supplements reduce oxidative stress. The aim of this study was to compare the effects of Ajuga and Ertomol-Tendo supplements on balance and EXPLOSIVE POWER of soccer players. Methods: Thirty-nine soccerl players voluntarily participated in this study. The subjects were randomly divided into three groups of 13 people: Ajuga supplement, Ertomol-Tendo supplement and placebo. In the pre-test, at the first and 48 hours after the implementation of the training protocol balance and expolosive POWER were assessed. The subjects took the supplements for 4 weeks and at the end of the supplementation period, the post-test phase was conducted similar to the pre-test. Balance was measured using foot RSscan and expolosive POWER was measure using vertical jump instrument. The data were analyzed by the analysis of variance test with repeated measurements (P<0. 05). Results: Inspite that balance and expolosive POWER increased following using supplement, but the it was not significant (P>0. 05). No significant differences was found between groups (P>0. 05) in balance and expolosive POWER. Conclusion: It can be concluded that the use of Ajuga and Ertomol-Tendo supplements has no significant effect on balance and EXPLOSIVE POWER in youth soccer player

Background: Volleyball is known as sport that requires high physical fitness, including muscle POWER, agility and reaction; hence, body composition and anthropometric features play important roles in this field. The purpose of this study was to investigate the relationship between anthropometric and body composition indices with lower limb EXPLOSIVE POWER in female volleyball players. Method: This correlational study was conducted in which 16 semi-professional female volleyball players with an average age of 20. 4 ± 1. 34 years and BMI of 22. 09 ± 3. 42 kg/m2 voluntarily participated. All volleyball players had a history of participation in the Tehran province volleyball league. First, data were collected and recorded by demographic questionnaire. Then, the body composition (fat percentage, muscle mass, visceral fat) was measured and recorded in the 3-hours fasting condition by body analysis device (OMRUN Bf511). Finally, Sargent Vertical Jump Test was used to evaluate EXPLOSIVE POWER of the lower limb muscles. Results: Pearson correlation coefficient was used at the significant level p <0. 05 for statistical analysis. The results indicated a significant positive correlation between muscle mass and lower limb EXPLOSIVE POWER (P <0. 02) and a significant negative correlation between EXPLOSIVE POWER and fat percentage (p <0. 05). Also, a significant positive relationship was found between height and EXPLOSIVE POWER of lower limb. Conclusion: The results of this study show that resistance training along with volleyball specific POWER training can increase the muscle mass as well as it is at the same time.

The purpose of the present study is to investigate the effects of plyometrics and weight training on the performance (a60- metre sprint run and EXPLOSIVE POWER) of physical education students. 30 male P.E. students age between 21 and 23 were selected for this study. Height, weight, 60- m. sprint run, and sergeant jumping POWER of the subjects were measured in a pre - test. Then the subjects were randomly divided into 3 groups of 10 including: two experimental groups: plyometrics and weight training, and a control group. Maximal muscle strength (quadriceps, gastrocenemius and hamstrings) in the weight training group was also measured. The experimental groups did selected exercises for 8 weeks, 2 sessions per week. The plyometric group, performed deep jump, jump over the cone, lateral obstacle jump, and half - squat jump over the box. Weight training group exercises included weight lifting with leg press, knee flexion, knee extention and toe raise. The total time of training for both groups was 48 minutes. In this training protocol, the control group did not do any specific types of exercise. At the end of training, the "sergeant" jump test and 60-m. sprint run test were administered to the subjects. The data were analyzed through descriptive and inferential statistics (analysis of variance, ANOVA, correlated - T, Tokey's post - hoc test). The following results were concluded from this study: 1. weight training and plyometrics had significant effects on EXPLOSIVE POWER and running pace of the subjects (p£0.05). 2. No significant difference existed between the weight training and plyometrics in their EXPLOSIVE POWER and running pace (p£0.05). The results of this study indicated that no significant difference existed between the effects of plyometrics and weight training in EXPLOSIVE POWER and 60-m. sprint run; and both of trainings affected the mentioned variables equally.