Improving the physical qualities of professional boxers by considering their personality traits

The study analyzes the development and improvement of physical qualities in modern sports and examines the optimal parameters in general and individual training of boxers. The paper describes a pedagogical experiment to explore the effectiveness of the author ’ s methodology for the development and improvement of physical qualities considering boxers ’ personality traits. The experiment involved 30 boxers from the national team of the Republic of Kazakhstan, which is among the strongest teams in the world (15 people in the experimental and 15 people in the control group). The experimental group demonstrated a statistically signi ﬁ cant improvement in 7 out of 9 dimensions: pull-up on the bar ( t = 2.927; P ≤ 0.01), bench press from the chest ( t = 2.253; P ≤ 0. 05), weight push from the chest in front ( t = 3.467; P ≤ 0.01), 100 m run ( t = 3.100; P ≤ 0.01), jump from a place ( t = 2.444; P ≤ 0.05), 1st 400 m run ( t = 2.654; P ≤ 0.01) and 2nd 400 m run ( t = 2.354; P ≤ 0.05). The experimental group signi ﬁ cantly surpassed its background results and the control group ’ s results in seven indicators of physical ﬁ tness out of nine. This fact suggests that the author ’ s experimental technique effectively improves the physical qualities of highly skilled boxers. A two-way analysis of variance showed higher ef ﬁ ciency of improving physical qualities when using the author ’ s methodology and the absence of differences between different weight categories. The study can be of practical use for sports coaches and psychologists who want to improve the physical qualities of athletes, following the methodology proposed by the author. In addition, the materials of this work can be useful in studying the management of performance and creating a favorable psychological climate for improving physical qualities of boxers, considering the characteristics of an athlete ’ s personality.


Introduction
O ne of the most important research questions in sports is physical fitness. It is relevant to most sports. Researchers examine it through different lenses. Some researchers separate general and special endurance in the structure of physical fitness, considering general endurance as the base on which the whole process of physical improvement is built (Kapo et al., 2021). Other authors give priority to special physical training (Aktaş et al., 2019;Muller et al., 2019).
Boxing occupies a special place among modern sports. The variety and intensity of motor activity distinguish this sport from others and emphasize its special status in physical improvement. However, the intensity and activity of motor actions are not only determined by a boxer but also by the behavior of their rival in the ring. In other words, there is a close correlation between a boxer's action intensity and an opponent's action intensity during the fight. The situation is different in the training process. Here, the intensity parameters are planned and programmed in advance based on a competitive activity simulation that considers a boxer's capabilities and unique features (Shum et al., 2016). These features should be considered both in general and specific physical training.
Scientific and educational literature on boxing presents various methods of development and improvement of general and specific physical fitness. Some approaches recommend using the methods of volitional training and the development of psychomotor qualities. However, very few authors offer specific methods and techniques for developing general and specific fitness based on the personal traits of boxers, including highly qualified boxers (Andruschishin, 2011).
The main task in the physical training of a high-level boxer is the development of technique and combat tactics, which should correspond to the physical and physiological development of the body. Furthermore, according to some authors, stress tolerance is also a vital component of training. All the above factors contribute to a balance between using different methods of attack and defense during combat. Depending on the combat tactics, boxers can use the right and left halves of the body according to the situation. It is known that the effect of attacking actions may depend on a boxer's ability to deliver strong blows with the greatest possible speed. At the same time, the balance of the whole body must be maintained, and a certain precision in the movements has been shown in a study involving fighters from Thailand (Tong-Iam et al., 2017). The researchers used software and modern optoelectronic equipment to create a model of the movements performed by a boxer during direct strikes. An athlete's axis of support was also considered. The model allowed the authors to identify three basic body positions in dynamics. The first is when a boxer transfers their weight to a leg distant from their opponent. It involves the detachment of the toes from the surface. This creates a situation where there is an opportunity to increase the distance of the blow and move the torso on an angular trajectory. The second stage is when the weight is transferred to the near lower limb, which had zero support force until that moment. At this stage, the beginning of a direct blow to an opponent occurs. The second stage takes approximately onethird of the total time used to strike. Finally, there is a complete transfer of weight and the actual striking at the third stage. Depending on the individual qualities of a boxer and their professionalism, the third stage takes from 30 to 45% of the total time needed for the punch. This stage is important for the performance of direct-type punches in terms of both sports and physical patterns. Such studies are now prevalent. They are state-ofthe-art in the science of studying sports and athletes. Aktaş et al. (2019) established specific muscle force values for arm and leg muscles in highly skilled boxers. They found that the muscles responsible for the rotational movements of the shoulder joint are much more developed in boxers than in other athletes, which provides them with the ability to deliver fast and accurate punches. To improve the effectiveness of boxers' training and their endurance, these authors recommend developing these muscles during training, particularly those responsible for the external rotation of the shoulder joints. Buśko (2019) found that the biomechanics values of ten muscle groups in total are almost 3100 N m. The author also established the maximum power output values of boxers and the results of upward-running and plain jump tests. The study also found asymmetry in the indicators of the hands, occupying near or far position to an opponent, on the example of a direct strike or hook. The far hand is hit with greater force than the near hand. The author recommended exercises that involve jumping or quick heavy physical exertion (Buśko, 2019).
El-Oujaji et al. (2019) used a special biomechanical suit to measure body stability indicators in French athletes. They found that this indicator equaled 50% for high-level boxers, which was due to the rational distribution of weight falling on the two legs. For lower-level boxers, such as juniors, the body stability indicator did not exceed 50%, which was associated with less control over the movement of their weight at the moment of the blow.
Thus, current studies of the physiological and physical foundations of boxing focus on the development of effective training methods that improve the performance of boxers. This trend concerns both European and Asian countries. At the same time, testing original training methods by comparing the athletes' results before and after the training cycle remains relevant and relatively underdeveloped. This determined the motivation and necessity of this paper. The present study focused on boxers in Kazakhstan. In recent years, Kazakh boxers have been showing increasingly better results. For example, Temirtas Zhusupov and Saken Bibosynov became world champions in 2021, whilst Makhmud Sabyrkhan and Serik Temirzhanov received silver medals at the World Boxing Championship held in Belgrade (Serbia) (TengriNews, 2021). Kazakhstan supports its athletes by providing them with funding depending on their level of sporting achievements. It gave an impetus for boxing development in Kazakhstan, and scientific research can focus on Kazakh boxers' achievements.
The research aims to study the development and testing of a new method for improving the physical qualities of professional boxers. The research objectives are to (a) develop the method that considers the individual qualities of boxers; (b) test the method; and (c) evaluate the results of the method's application in the experimental group using statistical analysis.
The study's authors have developed a methodology for improving the physical qualities of highly skilled boxers and conducted formative and ascertaining pedagogical experiments to evaluate its effectiveness. The authors assume that the experimental group of boxers will have better results at the end of the experiment than the control group in many physical performance tests.

Research methods and structure
Methods. The study took place in 2021 in Kazakhstan. The following methods were used in the experimental study. 1. Observation of educational and training process during the performance of exercises included in the original method for improvement of physical qualities of boxers. 2. Pedagogical testing, which included measuring nine indices of physical preparedness of highly skilled boxers before (background data) ARTICLE HUMANITIES AND SOCIAL SCIENCES COMMUNICATIONS | https://doi.org/10.1057/s41599-022-01348-5 2 HUMANITIES AND SOCIAL SCIENCES COMMUNICATIONS | (2022) 9:321 | https://doi.org/10.1057/s41599-022-01348-5 and after the experiment: push-ups in a prone position, pulling up on the bar, bench press, pushing the barbell from the chest in front of oneself, running 100 m, long jump from a place, first attempt to run 400 m, second attempt to run 400 m, third attempt to run 400 m. 3. Statistical methods, which included calculation of the arithmetic mean of physical fitness (), standard deviation (σ), Student's t-test (t), confidence level (P) for comparative statistical analysis and two-way analysis of variance (Han et al., 2020).
Research design. The pedagogical experiment consisted of two parts. The first part included a formative experiment to identify the effectiveness of the original method for improving physical qualities, developed considering the athlete's personality traits. The second part consisted of a two-factor analysis of variance to verify the technique's effectiveness for light, medium, and heavyweight categories. The participating boxers were selected based on their professional qualities. All participants were randomly divided into two equal groups of highly qualified boxers with similar levels of sports skill: an experimental group (15 persons) and a control (15 persons) group. The experimental group trained during the entire annual macrocycle using the author's method to improve general and special physical qualities. The control group trained in the usual mode according to the prescribed program for the entire sports season. Both groups were tested for physical preparedness before and after the beginning of the sports season using methods accepted for use in boxing and serving as informative and valid indicators. In the testing process, all requirements and conditions of the tests included in the examination program were observed. Both groups received identical training, identical accommodations, and identical meals.
The experiment was conducted during the sports season. Trained assistants carried out testing under the experimenter's supervision and Kazakhstan's national team coaches. The assistants were not informed about the purpose of the experiment.
Sample. Highly qualified boxers and members of the first and second squads of the national team of the Republic of Kazakhstan took part in the experiment. All boxers were men of the average age of 24.1 ± 1.3 years. The sample included 30 boxers, of which six people were honored masters of sports, 19 were highly skilled fighters of international class, and the remaining 5 were masters of sports. The 30 participants included three Olympic champions, six prize winners of the Olympic Games, and eight world champions. There were also prize winners of world championships, champions and prize winners of Asia and Asian Games of different years. All selected boxers corresponded to the criterion of the research: high professionalism, availability of prizes or master of sports title (at least), and high level of physical training.
For statistical analysis, the authors used the program Statistics 10 version to calculate the arithmetic mean of each parameter, standard deviation (S x ), results of using Student's t-test (t), and significance level of differences (P).
Consent to participate. All athletes gave their written informed consent to participate in the study. The participants got acquainted with the peculiarities of the experiment by reading the agreement.

Results
The data obtained in the initial and final tests for different types of physical activity are shown in Table 1.
Comparative analysis of the experimental and control groups' indicators showed that there was no statistical difference in the level of physical fitness between the two groups before the experiment. For all nine test indicators, Student's t-criterion does not reach the necessary critical values, although, in six tests, the control group has slightly better background indicators than the experimental group. This applies to the bench press, the barbell push press from the chest, the long jump, and all three attempts of the 400 m run.
The training process of the experimental group according to the method developed considering personality traits showed that after the experiment, the situation changed. These changes are reflected in Table 2. The experimental group improved results on all nine test indicators. For seven indicators Student's t-test results were significant, which means that these improvements were reliable: bench press (t = 2.535; P ≤ 0.05), pull-up bar (t = 3.278; P ≤ 0.01), bench press (t = 2.486; P ≤ 0.05), 100 m run (t = 2.437; P ≤ 0.05), 1st attempt at 400 m run (t = 2.891; P ≤ 0.01), 2nd attempt at 400 m run (t = 2.531; P ≤ 0.05).
3rd attempt at the 400 m run (t = 3.059; P ≤ 0.01). The improvement was not significant in the barbell push and the long jump. The t-test values were not of the required significance level for both cases. In general, it can be said that the original method tested in the experimental group had positive effects.
However, to be fully convinced of the method's effectiveness, it is necessary to compare the background results of the experimental group at the beginning of the experiment with those obtained after the experiment. These data are presented in Table 3.
The test results after the experiment significantly improved in the following seven indicators out of nine: pull-up on the bar (t = 2.927; P ≤ 0.01), bench press from the chest (t = 2.253; P ≤ 0.05), barbell pushing from the chest in front (t = 3.467; P ≤ 0.01), running 100 m (t = 3.100; P ≤ 0.01), jump from a place (t = 2.444; P ≤ 0.05), first attempt at running 400 m (t = 2.654;

R E T R A C T E D
A R T I C L E P ≤ 0.01), and the second attempt at running 400 m (t = 2.354; P ≤ 0.05). For the bench push-up and the third attempt at running 400 m, the improvement was random because the values of the Student's t-test did not have the required level of reliability (0.352 for bench press and 1.549 for running). This is due to a large standard deviation (S x = 59.19 and S x = 8.05) in the results of the boxers from the experimental group before the experiment, indicating that there was a significant dispersion of the last two indicators among athletes. For example, the best result in the bench push-ups from the prone position of subject C (305 pushups) was 4.9 times more significant than that of subject K (65 push-ups). Similarly, in the third attempt at 400 m run, the best result of subject S was 60 s, while the lowest result of subject T was 98 s. After the experiment, there was no such variation in performance. Boxers lagging behind improved their results, and the standard deviation normalized. Positive changes in the experimental group regarding the improvement of their physical qualities are shown in Fig. 1.

L E
The results of the two-way analysis of variance are presented in Table 4. The analysis showed that the actual F value (13.47) of factor A is greater than the standard F value (7.82) with a p-value < 0.01. Thus, the experimental and control groups demonstrated different physical fitness results after the experiment. The experimental group, which followed the new author's method demonstrated better results (actual F value = 13.47 > standard F value = 7.82).
For factor B, no significant differences were found for all weight categories of the boxers. All tested boxers, regardless of weight category, achieved approximately the same results in physical fitness (actual F value = 0.097 < standard F value = 3.5). The p-value is ≤0.05. The interaction of factors A and B indicates that boxers of different weight categories performed quite well both in the control and experimental groups when developing and improving physical fitness.

Discussion
The experiment showed that the better physical fitness of the test group, in the end, was due to the application of the author's methodology, as demonstrated through statistical analysis (see Fig. 1). The approach was tested on boxers from different weight categories. It had been suggested at the beginning that the technique's effectiveness might be different for different weight categories. For this purpose, a two-way analysis of variance was performed. The first factor (factor A) in the analysis was the training method (the traditional method of improving physical qualities and the original method, which considers athletes' personality traits). According to the classification used by the International Boxing Association (FIBA), all boxers are divided into light, medium, and heavyweight categories. The experimental group was divided into these categories (5 people in each). These groups served as the second factor (or factor B) in the analysis.
Due to different physical fitness measurement units, the authors decided to measure each boxer's integral physical fitness index. The solution to this problem was achieved using the standardization of test results. Standardization of physical fitness indicators was based on the ten-point Cattell scale (Ayan, 2020). The research found that anthropometry parameters in both boxers and athletes, in general, are significant initial characteristics that determine the degree of success in sport. Boxers' traits define their tactics and techniques later. Han et al. (2020) analyzed the anthropometric characteristics of boxers over 130 years. The researchers found that these parameters tend to increase in high-class boxers at the peak of their careers. The study covered the period from 1889 to 2019. The sample included 237 prizewinning and losing boxers from the four most representative boxing competitions. Most of the sample consisted of representatives of the Caucasian race (125 people), followed by the Ethiopian race (93 people). The present study focused on the Mongoloid race (which includes the Kazakhs). This contributes to the study's significance since few include this group. Han et al. (2020) also found that prize-winning boxers were slightly taller (by 3.5 cm) and heavier (by 3.5 kg) than the defeated. Moreover, they had greater arm circumference (also by 3.5 cm), a wider neck (by almost 1 cm), biceps muscles (by 1 cm), and forearm muscles (also 1 cm). It was also found that a body index corresponding to 28-30 kg per 1 m 2 was the norm for heavy and superheavy weights. Kumar and Tyagi (2019) continued these studies and found a correlation between the frequency of boxers taking prizes and height, the proportion of body fat, and limb lengths (arms, legs, and forearms). The authors suggest that arm length is one of the most predictive indicators. In this paper, boxers of different weight categories were considered. The data obtained confirmed the previous results-heavyweight fighters had significantly better results than boxers from lighter categories.
One of the main training goals in boxing is to increase the power of muscles and muscle groups (Frey, 2000;Han et al., 2020). This is a condition for developing such characteristics as endurance and accuracy of blows (Chen et al., 2019;Cunniffe et al., 2017). In this regard, both sports medicine scientists and coaches are constantly searching for new techniques to develop power, speed, and accuracy (Ayan, 2020;Issurin and Shkljar, 2001;Kim et al., 2018;Sienkiewicz-Dianzenza and Maszczyk, 2019). This paper proposes a new successfully tested technique applied to boxers from other regions. Loturco et al. (2018) found that bench presses and other barbell exercises can significantly improve a boxer's power, given the training frequency of 14 sessions in 7 weeks. The applied load can be increased by 5-10% of a boxer's weight index. A break of 5 min is recommended between each exercise. These exercises have also been known to significantly improve boxers' results from Brazil.
It is well-established that any boxer will become fatigued during a fight, which is primarily characterized by a decrease in the intensity and speed of their movements. Malik (2019) Wandee and Benjapalakorn (2018) tried to classify athletes according to this parameter using a sample of amateur-level boxers. The analysis had an individual approach, which means it considered each boxer's strong and weak features. The original method proposed in this paper is also based on the individual approach, which provided positive results for the experimental group at the end of the experiment.
Further testing of the technique is necessary, considering the physiological traits of each of the tested boxers (heart rate, pulse, blood pressure of systolic and diastolic type). The method can be applied in practice to increase boxers' performance.

During the development and improvement of physical
fitness, it is necessary to take into account the following factors: (a) specific requirements of a sport for the physical preparation of an athlete, (b) the development of certain physical qualities of an athlete, (c) functional capacities of an athlete (physique, age, and qualification), and (d) stages and periods of the training process. 2. The improvement of the physical fitness parameters of the experimental group can be reliably linked to the use of the original author's methodology. In the final series of tests, the experimental group demonstrated a statistically significant improvement in 7 out of 9 dimensions: pull-up on the bar (t = 2.927; P ≤ 0.01), bench press from the chest (t = 2.253; P ≤ 0.05), weight push from the chest in front (t = 3.467; P ≤ 0.01), 100 m run (t = 3.100; P ≤ 0.01), jump

R E T R A C T E D
A R T I C L E from a place (t = 2.444; P ≤ 0.05), 1st 400 m run (t = 2.654; P ≤ 0.01) and 2nd 400 m run (t = 2.354; P ≤ 0.05). 3. Similarly, seven out of nine indicators of physical fitness in the experimental group improved compared to the control group (P < 0.05 and P < 0.01). 4. The two-way analysis of variance showed higher effectiveness of the author's technique not finding the superiority of any weight category in achieving higher results. Representatives of different weight categories of boxers interacted quite successfully both in the control and experimental groups to develop and improve physical qualities.