The effect of eight weeks of volleyball training with and without prejumping on execution, delayed muscle contusion and scrambling

Master's thesis in the field of physical education and sports science, sports pathology

Abstract

Context: In plyometric exercises, simulated movements with the main skills of the desired sport are used with the aim of increasing the player's power. The aim of this study was to evaluate the effectiveness of 8 weeks of plyometric training with and without short hurdles on the jump height and the quality of the spike and serve skills of skilled female volleyball players. Methodology: 20 skilled female volleyball players aged 14 to 27 years were divided into two training groups with and without hurdles. The training program of the two groups was similar and included three training sessions of 1.5 hours per week for 8 weeks. In each training session, 30 minutes of time was devoted to plyometric exercises. The obstacle group performed these exercises using a cardboard obstacle (3 x 3 x 60 cm). The presence of an obstacle would make pre-jumping mandatory and jump in a more precise place. The amount of delayed muscle contraction and struggle of the subjects was measured by specialized scales once a week to ensure that the training pressure of the two study groups was the same. Jumping rate was measured by the modified Sargent jump test and the quality of spike and service skills was measured by specialized tests in two stages before and after the training period. Statistical analysis was performed through analysis of variance for repeated data. Findings: In three tests of vertical jump, spike skill, and service skill, the difference between the groups and interaction between the groups was insignificant (P ? 0.05). This means the similarity of the two experimental and control groups from the beginning to the end of the research. However, the intra-group differences of all three skill tests were significant and meant a significant improvement of the two groups. In vertical jump, the group with obstacle improved by 2.9 cm and the group without obstacle by 1.9 cm (P=0.006 and F=(1,18) 9.66). In the types of spikes, the group with the barrier improved by about 40% and the group without the barrier by about 22% (P?0.032 and F?(1,18) 5.41). In the service skill, the group with barrier improved by 47% and the group without barrier by 31% (P=0.000 and F=(1,18) 27.96). During 8 weeks of training, both groups were similar in terms of struggle and had done relatively hard struggle. None of the intergroup, intragroup, and interaction comparisons were significant for the struggle factor (P ? 0.05). In terms of bruises, two groups had the least possible bruises during 8 weeks of training. For this factor, only the intra-group comparison was significant (P=0.006 and F=(1,18) 9.66) and it showed that during the training, the concussion of both groups had a significant decrease.

Discussion and conclusion: The non-significance of intergroup and interactive differences between the two groups shows the success of the researcher in equating the two control and experimental groups at the beginning of the research. The high level of struggle and the low level of bruising also indicate the researcher's success in adjusting the load of training sessions. The results showed that, in all three skill factors, both groups had significant progress. Therefore, both training styles are recommended for trainers. In all three measured skill factors, the training group with obstacle had more progress, but this interaction was not significant at the 0.50 level. Therefore, it is still not possible to say with certainty that using a low barrier is more desirable. Increasing the sample size or the volume and training period in future studies may show the validity of this claim better.

Introduction

The power and ability of the legs in running, jumping or jumping is important in most sports, but this point is doubly important in some of them. For example, in volleyball, the ability to jump with a pair of legs contributes a lot to winning. Plyometrics is an exercise that relies on increasing a person's ability to combine speed and strength. Plyometrics creates a mechanism by which the athlete can have a faster start, a faster change of direction and a greater acceleration, which improves movement speed. Since plyometric exercises are new and effective, they have found their place in the training program of many sports that are somehow related to speed and jumps. In this research, if the role of pre-jump in vertical jump height is determined, based on the findings, it is possible to introduce superior jumping technique. In this case, knowledge is provided so that coaches can act in a better way to prepare athletes for their careers.

1-1. Description and statement of a research problem

Jumping higher has always been one of human dreams.In many sports, jumping in different directions is very important. In most ball games (volleyball, soccer, handball, basketball) and some non-ball games (martial sports, gymnastics, and diving) that include extroverted [1] and introverted [2] contractions, and after each extroverted contraction, an introverted contraction occurs in the muscles involved in movement, the ability to jump a pair of legs plays a determining role (1). Jumping is vital in performing many sports skills, including high jump, rebounding and blocking in basketball, and spiking and defense in volleyball. The coordination of movement and the speed of force transmission by the joints and muscles of the ankle, knee and thigh are the most important characteristics of performing vertical jump (46). Today, volleyball has become one of the most important and widespread sports in the world, and participation in this sport requires physical skills and execution, which often depends on individual abilities in jumping and landing. For example, according to the analysis of the game of female volleyball players, each player makes an average of 22 jumps in each game. These jumps are divided into single leg jumps with right or left leg and pair leg jumps. In the above research, it was reported that 84% of the jumps were performed with a pair of legs and 16% of the rest were performed with a single leg. Also, about 44% of defensive jumps were performed with a pair of legs and the rest with a single leg (87). In volleyball, jumping is an explosive movement in which the two factors of muscle strength and speed are involved; and proper jumping technique play a role. Meanwhile, jumping technique is more important than strength and speed. Correct jumping technique has two basic parts: 1) movements before the jump and 2) movements during the jump. Research has shown that jumping with pre-jump is better than standing jump (66).

Vertical jump is one of the essential skills for the success of an athlete in performing a jump pass, jump serve, defense and spike of volleyball players. The success of an athlete is not only in jumping a lot, but reaching the maximum jump height in the shortest time is the criterion. A volleyball match is played up to 5 sets, that is, a match lasts about 90 minutes, during which a player performs about 250 to 300 explosive movements by leg muscles (43). Therefore, many efforts have been made to increase the amount of vertical jump, and in this direction, many training methods have been invented, one of which is plyometric exercises [3]. Plyometric exercises are known as a method to improve explosive power (10). Plyometrics is a type of physical exercise that is performed with the specific purpose of sports to increase power or explosive power and enables the athlete to use maximum power in minimum time. Unlike the past, one should not have unreasonable expectations from this type of exercise. Plyometrics does not give the athlete extraordinary strength, but it strengthens the explosive power of the muscles (32). Plyometric exercises are those activities that allow the muscle to achieve maximum explosive force in the shortest possible time. From the point of view of performance, plyometric movement includes a fast and powerful movement using pre-jump or stretching before the movement, which is performed using reflex-stretching force. The purpose of plyometric exercises is to increase the power of movements performed using the natural elastic components of the muscle (tendons) and stretch reflex (75). Many sports and bodybuilding activities (such as plyometric exercises) require landing from jumps, which leads to the return of force to the body and can increase the possibility of injury (28).

Although plyometric exercises have been shown to improve performance variables, they also have the potential to cause injury. Especially when athletes are subjected to new exercises or training pressure. Exposure to new exercises, especially in external exercises, increases force production in the skeletal-muscular system and can lead to delayed muscle contusion[4]. Although the use of plyometric exercises leads to an increase in the height of the vertical jump, the possibility of muscle contusion and damage following such exercises has been shown (90). In this research, the focus is on the movements before the jump, and the researcher will try to answer the following questions: 1) Does the pre-jump increase the vertical jump or not? 2) Does pre-jump improve volleyball skills (spike and serve)? 3) Does training with pre-jump increase delayed muscle contusion?

1-2.