INTRODUCTION

An analysis of the literature of recent years shows that the attention of a large number of studies is focused on the health of schoolchildren and the insufficient level of their motor activity [1, 2]. During school years, a vital foundation of motor skills and abilities of children from the first grade is formed. Under the supervision of a teacher, students perform a fairly large number of physical exercises and different combinations at each lesson. The main task of physical culture at school is the comprehensive harmonious development of the personality of students [3]. The program strongly influences the development of basic physical abilities (endurance, speed, flexibility, strength, agility). It should be noted that physical abilities are interconnected and it is quite difficult to develop one quality in isolation. That is, if we develop endurance, then it affects other abilities, this has been proven by several studies [4, 5].

In previous studies, we have proven the effect of coordination training on indicators of other physical abilities [6]. However, coordination training and dexterity development are typical for children in primary school. And for middle-level schoolchildren, the high-speed, power, and endurance load will be relevant. Physical qualities such as speed and strength abilities are best developed at the adolescent age of 13 to 14 [7, 8].

In working with school children of any age, it is important to use a differentiated or individual approach at each lesson, while the criterion of differentiation may be the level of physical or technical training, the growth of students, or some other characteristics. This approach to working with children is quite effective and allows you to reveal almost the entire motor potential of each child [9-11]. Of course, a promising direction in the individualization of learning is the type of nervous system [12].

In this study, we set ourselves a new goal – to determine the effect of a set of exercises for the development of strength and speed for the flexibility of schoolchildren, taking into account the nervous system type.

MATERIALS AND METHODS

Participants

The academic experiment was attended by schoolchildren aged 13-14 years in the number of 40 people from class 7a (control group - CG) and class 7b (experimental group - EG).

Procedure

The study was conducted in 60 schools in Kirov (Russia). The study lasted from January 12 to March 20, 2020. There were 8 girls and 12 boys in the control and experimental groups. All the children were on health grounds of the main medical group and admitted to physical education. During the experiment period, 20 lessons in CG and 20 lessons in EG were conducted, each lesson lasted 40 minutes. Physical education classes were scheduled twice a week in class 7a (Tuesday 8.50-9.30, Friday 9.40-10.20), in-class 7b (Tuesday 9.40-10.20, Friday 8.50-9.30).

Children from class 7a were engaged in a standard program for students of grades 1-11 in physical culture at school [3].

Schoolchildren from grade 7b used the usual program and performed speed and strength exercises for 8-10 minutes after the warm-up. The simple set of exercises required maximum dedication from the students, it included such exercises as running, body turns, acceleration, pull-ups, push-ups, squats, working with dumbbells, and others. Physical activity for children in EG was different. Children with a strong nervous system work out faster, but get tired quickly, so they are characterized by frequent changes of exercises and fewer series, the contrary can be inferred from the children with weaker nervous systems [12].

All children took a tapping test, which differentiated schoolchildren by the strength of the nervous system.¹² According to the test results, the children were differentiated into subgroups.

Indicators of speed and strength abilities were determined by three tests:

long jump from a place with a push with two legs (leg strength) [13], lifting the torso from the supine position (torso strength) [14], flexion and extension of the arms at the stop while lying on the floor (arm strength) [15].

The flexibility of schoolchildren was determined using the test “forward-leaning from an upright position on a gymnastic bench” [3].

In the study, when calculating the results, we used the Excel program. According to the results of the study, the average values in each group, the standard deviation from the indicators were determined.

RESULTS AND DISCUSSION

After the tapping test procedure, children in grades 7a and 7b received 10 schoolchildren with a strong and 10 with a weak nervous system in the arousal process. Table 1 shows the results of the study in CG.

Table 1 shows that students from the CG improved their performance in both subgroups, although they studied according to the standard program, without taking into account the differentiated load. Indicators in the “leg strength” test of the stronger nervous system teenagers, increased by 3% as compared to the ones with weak nervous systems which increased by 4%. A similar phenomenon was seen in the “torso strength” with the indicators of weaker nervous system children increasing by 4% contrasted to the 2% increase in their counterparts, .3% was an increase in indicators in children with a strong nervous system in the test “arm strength”, and in children with a weak nervous system 2%.

Flexibility indicators also did not significantly improve showing a 6% (7.2±1.3 to 7.6±1.4) increase in the stronger nerved children as compared to the 8%(7.5±1.2 to 8.1±1.3) on in the weaker ones.

Well, the usual physical education program at school is not so bad, it has a positive but not significant effect on the physical qualities of students. Table 2 shows the results of the study in EG.