Purpose: This study was accomplished to investigate the electromyographic activity of 3 PLYOMETRIC EXERCISES (tuck jump and single leg hop in sagittal and frontal planes) to find out the appropriate procedures for strengthening biceps femoris and gluteus medius muscles.Methods: The kind of study is applied and data were collected from the supervised EXERCISES of 15 male athletes without injury of lower extremity from Tehran University, which participated voluntarily in this research. It was assumed that subjects expend the extreme potential during their activities. Statistical analysis was made using repeated measures ANOVA to investigate the muscle activity in feed forward and feedback phases of landing with SPSS 20.Results: Significant differences (P£0.05) were found between treatments in relation to feed forward and feedback phases of muscles activities. Single leg hop in sagittal and frontal planes showed the highest activity of biceps femoris and gluteus medius in feed forward phase, respectively. Nevertheless, tuck jump demonstrated the lowest activity of these muscles in both phases.Conclusion: According to the results, single leg hop in sagittal and frontal planes could be the most appropriate EXERCISES for improving strength and neuromuscular system of gluteus medius and biceps femoris. We should take special attention to these 2 PLYOMETRIC EXERCISES in exercise programs. However, tuck jump in comparison with 2 other EXERCISES show less effectiveness.

Purpose: Despite the widespread use of cryotherapy in sports, there is no specific evidence of its impact on muscle activation, especially following fatigue-induced EXERCISES. This study aimed to assess the impact of cryotherapy alone and after PLYOMETRIC EXERCISES on knee muscle activation during the drop jump task. Methods: A total of 35 active female subjects (Mean±, SD age of 22. 74±, 2. 10 years, mean body mass index [BMI] of 20. 02±, 2. 55 kg/m2) participated in this quasi-experimental study with a pretest-Post-test design. There were three experimental groups (20-minute cryotherapy, PLYOMETRIC, and PLYOMETRIC-cryotherapy) and a control group. Electromyography (EMG) amplitudes of knee muscle activation (rectus femoris [RF], biceps femoris [BF], tibialis anterior [TA], medial gastrocnemius [MG]) were measured and compared in three phases of the dropjump task (one feedforward preactivation and two feedback eccentric and concentric phases). Skin temperature was recorded before and after cooling intervention as well. For comparisons, repeated measure analysis of variance (ANOVA) was used at a significant level of 0. 05. Results: The results showed that the skin temperature decreased significantly after cryotherapy and was maintained for 20 minutes. No significant changes were observed in the EMG of knee muscles in the feedforward and concentric phase of the drop jump task in any groups (P>0. 05). However, RF activation decreased following cryotherapy immediately and after 20 minutes as an eccentric phase (P=0. 01) and had a significant difference from the control group (P=0. 01),besides, EMG activation decreased in cryotherapy, PLYOMETRIC, and PLYOMETRIC-cryotherapy groups immediately (P=0. 01). However, no significant differences were seen between them and the control group (P>0. 05). Conclusion: According to the present results, cryotherapy alone and after fatigue-induced PLYOMETRIC training had a minor effect on the knee muscle activation during a functional jumping movement, but the impact of these changes on knee biomechanics is insignificant, hence, further studies are essential for a better conclusion.

Background: Varieties of exercise therapy methods are used in rehabilitation in order to improve muscle function. Optimal function of muscles results in improvement of functional activities; as a result, these activities would be achieved in a shorter time with the reduction of energy wasting. The purpose of this study was to evaluate the effects of PLYOMETRIC and strengthening EXERCISES on the quadriceps muscle strength in girl students of Zahedan University of Medical Sciences.Methods and Materials: This experimental study was performed in Zahedan in 2005. Thirty six girl students aging 20 ± 1.2 years among residents of Mojtameh dormitory of Zahedan University of Medical Sciences were studied through simple non-probability sampling. Subjects were randomly assigned to either a PLYOMETRIC EXERCISES group or a strengthening EXERCISES group. The quadriceps muscle strength (kg) was measured using hand-held dynamometer before and after 10 sessions of intervention. The first group received PLYOMETRIC EXERCISES. Strengthening EXERCISES were given to the second group. Independent and paired t-tests were used for comparison between the pretreatment and post treatment results between groups and within groups, respectively.Results: The strength of quadriceps muscle was increased from 12.1 ± 3 to 14.7 ± 3.8 (kg) in the PLYOMETRIC EXERCISES group and from 12.4 ± 3.1 to 14.9 ± 3.9 (kg) in the strengthening EXERCISES group (P<0.0001). No significant difference was seen between two groups after and before intervention. Independent-samples t-test identified that there was no significant difference between two groups with respect to mean difference of the quadriceps strength.Conclusions: The results, in spite of conventional opinions, showed that there was no difference between PLYOMETRIC and strengthening EXERCISES regarding quadriceps muscle strengthening. Both types of EXERCISES increased the quadriceps muscle strength. Therefore, according to patient conditions, either type of these EXERCISES can be used for exercise therapy in knee pathologies and the quadriceps muscle strength deficit.

Introduction: Obesity and how fat is distributed in the body, especially in the middle part of the body, is a good predictor of future diseases, and exercise is one of the best non-pharmacological methods in the prevention and treatment of obesity. Therefore, the aim of this study was to determine the effect of de-training following PLYOMETRIC EXERCISES on obesity indices and physical fitness factors of male students. Methods: In the present quasi-experimental study, 20 male students from Alborz University physical education students were selected voluntarily and studied in 2 groups of PLYOMETRIC training 10 people and control group 10 people (homogenized based on body mass index). To collect data, a demographic questionnaire, to evaluate the aerobic power of "Astrand Test", to evaluate the anaerobic power of "Sergeant Jump Test" and to measure the percentage of fat by "Jackson and Pollock Skinfold Test" were used. Also, the subjects' body mass index was measured by dividing weight by height squared (m) and (waist-hip ratio) by dividing waist circumference by pelvic circumference. After evaluating and recording the initial data of the subjects in the intervention group, PLYOMETRIC EXERCISES were performed for 6 weeks and the post-test data were recorded in the same conditions as the pre-test and after the end of the training period. After evaluating and recording the initial data of the subjects, the intervention group performed PLYOMETRIC training for 6 weeks, including 3 and 4 sessions per week with one day in between. In the same conditions as the pre-test, the data related to the test phase and after 6 weeks data related to the post-test phase were recorded. Data analysis was performed in SPSS. 23. Results: Findings showed a significant effect of performing PLYOMETRIC training for 6 weeks on aerobic (34. 67±, 2. 43_39. 58±, 2. 58 ) and anaerobic capacity (104. 23±, 8. 07_132. 25 ±, 6. 49 ), waist to hip ratio (0. 84±, 0. 17 _ 0. 91±, 0. 13 ), body fat percentage (14. 54±, 2. 18_11. 49 ±, 2. 75 ) and body mass index (23. 01±, 1. 68_ 20. 08±, 1. 93 ) in PLYOMETRIC group (P<0. 05). However, after 6 weeks of de-training, almost all training achievements for the subjects in the training intervention group disappeared, which indicates the principle of long-term training in performing PLYOMETRIC training. Conclusions: Findings confirmed the effect of PLYOMETRIC training on cardiorespiratory function (significant increase in aerobic capacity) as well as improving health indicators. Therefore, due to the principle of diversity in training and the ease of using the gradual overload process in performing PLYOMETRIC training (due to the nature of PLYOMETRIC training), PLYOMETRIC training in the field of health is recommended as an alternative training method for continuous aerobic training. However, it should be noted that the gains of PLYOMETRIC training will disappear after a period of non-training.

Introduction: The rate of football-related traumas is high. However, greater levels of fitness may decrease the probability of these injuries. Researchers believe that PLYOMETRIC training can have significant short-term results. This study aimed to investigate the effects of PLYOMETRIC EXERCISES on athletic performance (speed, balance, and vertical jump ability) of male amateur futsal players. Materials and Methods: Thirty male amateur futsal players were randomly divided into control and PLYOMETRIC groups. All participants went through 15 minutes of standard warm-up activity, and then they were asked to perform the tests. The athletes of the PLYOMETRIC group also completed three rounds of PLYOMETRIC jumps and then were assessed 3, 10, 15 and 20 minutes after the warm up. The athletes of the control group were evaluated 3, 10, and 15 minutes immediately after the standard warm-up activity. Results: The study findings indicated an overall improvement in balance and vertical jump scores of amateur futsal players following PLYOMETRIC EXERCISES (P<0. 05). However, there was no significant effect on athletes’ speed. Speed, vertical jump, and balance did not significantly change in the control group. Conclusion: Vertical jump and balance ability may improve immediately after PLYOMETRIC EXERCISES. Further studies are necessary to reassess speed test results.