عنوان مقاله [English]
Nowadays, most of the championship coaches are looking for new methods of designing their athletes’ exercises; one of these methods is plyometric (explosive) exercise in which the stretch-shortening cycle is practiced. this exercise is done for mucle stretch (extravasation) and it is immediately followed by rapid shortening (Intra ventricular). Therefore, the effectivness of this type of exercise on muscle performance is evaluated using standard physical fitness tests. .The population of this study included 400 volleyball players from different clubs of Semnan city. Out of the mentioend population, 20 people were selected based on height, weight, age and volleyball talent tests, and they were randomly assigned to two groups incouding a cotnrol and an eperimetnal group (10 people in each group). The control group received no exercise, and the experimental group received standard plyometric training 3 sessions a week. In these sessions, the muscle performance (agility, endurance, leg flexor strength and explosive power) was evluated by digital devices at weeks 4, 8 and 12 (4 weeks of detrainig) as the pretest. The results showed that there was a significant difference between the effects of the plyometric exercise and detraining on endurance, leg muscle strength, and explosive power; however, there was no significant difference between plyometric training and detraining on the athletes’ agility. According to the results of the post-test compared to the pre-test, it can be stated that plyometric trainign and non-exercise training have respectively resuteld in the higehst increase of explosive power by 10.9%, endurance by 4%, and leg muscle strength by 3.8% with the mean of 3.8%. However, these exercises had not effect on agility.