EFFECTS OF LADDER TRAINING ON THE MOBILITY OF VOLLEYBALL PLAYERS

ABSTRACT Introduction: The step movement in volleyball is a fundamental skill that volleyball players must master, being the basis of the support of all other techniques of this sport. Objective: Explore the effect of ladder training on the mobility of high school volleyball players. Methods: Twenty high school male volleyball players aged 16-17 were selected as experimental volunteers. Randomly divided into experimental and control groups, 10 individuals in each group received a training intervention for 8 weeks, with ladder training added to the experimental group. Results: Both pieces of training resulted showed positive effects on the improvement of movement ability and speed and could effectively improve the athletes’ movement speed ability. Conclusion: Through systematic ladder training, the excitatory conduction time in the reflex arc of athletes was significantly reduced, leading to a faster response to various signal stimuli, bringing the athletes’ central nervous system to a state more prepared for sports practice. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.


INTRODUCTION
The movement of footsteps in volleyball is a basic skill that volleyball players must master, and it is the most fundamental guarantee to support the entire volleyball technique. 1The current development trend of competitive volleyball strengthens the prediction in advance and moves at a faster speed, more flexible footsteps are used to command the heights quickly, which requires athletes to have flexible steps to ensure that they can take an advantage in the game, whether in attacking or defending, in order to pose a greater threat to the opponent.And in college volleyball training, the training methods and means are often

METHOD Experimental method
Select 20 high school men's volleyball players aged 16-17 years old from middle school A as experimental subjects, the subjects are required to be healthy, without congenital chronic diseases and serious sports injuries, they are randomly divided into experimental group and control group, the members of each group are 10 people each. 3The experimental period is from October 12, 2020 to December 13, 2020, a total of 8 weeks.The experimental group added the ladder training experimental intervention in the 8-week training, while the control group adopted the traditional training method, and strictly controlled the variable factors during the experiment, it is sorted and analyzed, and finally a conclusion is drawn. 4ombined with the physiological characteristics and developmental characteristics of high school students, five test indicators were selected.Among them, the test indicators of the moving speed ability are the cross quadrant jump, the half-meter movement, and the 36m movement, and the test indicators of the reaction ability are the hexagonal ball response test during the starting reaction. 5

Mathematical statistics
The data obtained in this test were recovered and grouped, and the relevant data was imported into Excel, SPSS23.0 and other software for inspection and analysis, and a conclusion was drawn.

Logic Analysis
By summarizing the test data of the experimental group and the control group before and after the experiment, conducting scientific research and analysis, and earnestly summarizing whether the ladder training is effective in improving the mobility of high school volleyball players, the conclusions and suggestions of this paper are finally drawn.

Ethical Compliance
Research experiments conducted in this article with animals or humans were approved by the Ethical Committee and responsible authorities of Hebei sport university and Jiangsu Normal University following all guidelines, regulations, legal, and ethical standards as required for humans or animals.

Comparative analysis of the test index results of mobility between the experimental group and the control group before the experiment
Before the official start of the experiment, an independent sample t-test was conducted on the performance of the 20 volleyball players in A in the mobility ability index, the specific test data results are shown in Table 1.It can be seen that there is no significant difference in the cross quadrant jump index half-meter movement index 36m movement, the start reaction time, and the hexagonal ball reaction test index between the two groups of subjects. 6o sum up, the experimental group and the control group are divided into reasonable groups, and there is no significant difference between the test indicators, so experimental research can be carried out.
Comparative analysis of the test index results of mobility between the experimental group and the control group before and after the experiment 1. Comparative analysis of the test index results of the movement speed ability between the experimental group and the control group before and after the experiment The data before and after the experiment were compared and tested for differences.After inspection, the three test indicators of the movement speed ability of the experimental group were P<0.01 before and after the experiment, showing a very significant difference, indicating that the experimental group after training, the three indicators of movement speed ability have been significantly improved; The three test indicators of the movement speed ability of the control group, before and after the experiment, P<0.05, showed a significant difference, indicating that the control group after training, the three indicators of movement speed ability have also been improved, and the specific content is shown in Table 2 and Table 3.The comparison chart of the growth rate between the experimental group and the control group is shown in Figure 1. 7 The results show that the training of the experimental group and the control group has a good effect on the improvement of the movement speed ability, and can effectively improve the movement speed ability of the athletes. 8The reason for the improvement may be that the two groups of athletes have undergone systematic training, which has improved their physical abilities in all aspects, and can make better use of their physical functions during the test, which fully reflects the training effect.From the three test indicators of moving speed ability, it can be seen that the ladder training has a more obvious improvement effect on the test indicators related to the jumping ability compared with the traditional training.
2. Comparative analysis of the test index results of the reaction ability between the experimental group and the control group before and after the experiment Ladder training is more conducive to improving the ability of volleyball players to respond to this test at the start, after experimental intervention, the hexagonal ball response ability of the experimental group has been significantly improved, and the control group has also improved the hexagonal ball response ability after training. 9Ladder training is of great help to the improvement of lower limb gait rhythm, the coordination and development of the nervous system and the muscular system.Through systematic ladder training, the excitatory conduction time in the athlete's reflex arc is significantly shortened, and the athlete can quickly respond to various signal stimuli, so that the human central nervous system can reach an ideal state.Athletes in the middle of a volleyball match, need to be ready to accept external stimuli at all times, and make a quick response, the direction and trajectory of the volleyball flight and the change of the speed of the ball and other factors always test the volleyball player's reaction ability.

Comparative analysis of the test index results of moving speed ability after the experiment
After the experiment, it was found that the scores of both the experimental group and the control group improved after 8 weeks of training, through the difference test, it was found that the P values of the three movement speed ability test indicators were all less than 0.05, which proved that there was a significant difference between the experimental group and the control group after the experiment, that is, the ladder training could better improve the movement speed ability. 10he specific content is shown in Table 4.

Comparative analysis of the results of the post-experiment reaction ability test indicators
After the experiment, the difference test of the hexagonal ball reaction test results between the experimental group and the control group was carried out, and the result was P<0.05, there was a significant difference in the hexagonal ball reaction test between the experimental group and the control group after the experiment, it is proved that the ladder training method is more conducive to the improvement of the performance of the hexagonal ball response test.See Table 5 for details.

DISCUSSION
After a series of traditional mobility training, the control group, in addition to the test index of starting response, the scores of other test indicators have improved to varying degrees, but the improvement is smaller than the various test indicators of the ladder training.The reason may be because the body is in the process of training, it has corresponding adaptability to the stimulation, but cannot further stimulate and effectively improve the various qualities of the athlete's body, so this may be the reason why the traditional training does not have a ladder training performance.

Figure 1 .
Figure 1.Comparison of the growth rate between the experimental group and the control group.
2ingle, this requires coaches to use new training methods and means to improve the training interest of athletes, and achieve the best training effect with half the effort.As a new method of training athletes' agility, the ladder training method has a variety of training methods, it is not only interesting, but also can exercise the agility of athletes well, and it is a good training method for training volleyball players' footsteps.2

Table 1 .
Comparison statistics of the test data of mobility ability between the experimental group and the control group before the experiment.

Table 2 .
The comparison statistics of the movement speed ability of the experimental group before and after the experiment.

Table 3 .
Comparison statistics of movement speed ability before and after the experiment in the control group.

items Before the control group After the control group P Growth rate
Each author made significant individual contributions to this manuscript.Jing ZHOU: writing and performing surgeries; Yunrui Xu: data analysis and performing surgeries, article review and intellectual concept of the article.

Table 4 .
Comparison statistics of the movement speed ability between the experimental group and the control group after the experiment.

Table 5 .
After the experiment, the experimental group and the control group compared the results of the hexagonal ball reaction test.