PhD, Associate Professor J. Herbert¹
PhD, Associate Professor K. Garwol²
PhD, Associate Professor L. Zareba³
1 Institute of Physical Culture Sciences, College of Medical Sciences at Rzeszów University, Rzeszów, Poland
2Institute of Sociological Sciences, College of Social Sciences, Institute of Sociological Sciences, Rzeszów, Poland
3Institute of Computer Science, College of Natural Sciences at Rzeszów University, Rzeszów, Poland

Corresponding author: jherbert@ur.edu.pl

Keywords: physical activity, accelerometery, children, young people, sedentary lifestyle.

Abstract

Objective of this paper was to determine the level of physical activity of children and young people based on the MVPA index, number of steps, as well as sedentary time to analyze the young people's lifestyles and make them aware of whether the level of physical activity is sufficient, or whether action should be taken in order to make children and young people more active in this respect.

Study methods and structure. A diagnostic test of physical activity of pupils and students aged 7-18 was conducted in the School Complex in Zarzecze (Podkarpackie Province, southern Poland) in 2018, from April to June 2018, with the written consent of the parents and the children themselves. 108 pupils and students (49 girls and 59 boys) took part in the study. Regular school attendance, teaching results, observations, interviews and teachers' opinions were taken into account as a basis for setting up the group. The criterion for a pupil or a student to be included in the project was regular attendance at all classes during the week. Within the framework of the study, anthropometric measurements were made, which took place between 8:00 and 10:00 am.  The ActiGraph WGT3X-BT accelerometer (Pensacola, USA), which is a 3-axis accelerometer, was used in this study. Nowadays, these accelerometers are used for the purpose of conducing analyses of physical activity levels. The study subjects were instructed to wear the accelerometer for seven subsequent days, 24 hours a day. They were also informed that they must not use the accelerometers for spraying or water-related activities, as it must not come into contact with moisture. The ActiGraph data was analyzed using Actilife 6.0 software. In addition, the values of weight and height were measured and the Body Mass Index (BMI) was calculated by squaring the body size (kg / m²) BMI (kg/m²). The following parameters were analyzed: BMI, Sedentary, MVPA (Moderate-to-Vigorous Physical Activity) and number of steps.

Results and Conclusions. For many generations, there have been changes in the course of the population's somatic development and these changes have been steadily speeding up. They are called 'secular trends'. One of their signs is the acceleration of biological development and adolescence period. These changes are primarily related to the constantly improving social and economic situation and the improvement of the population's standard of living. These factors are, among others: change of eating habits, an improvement in environmental conditions, an increase in the level of education and better quality of health care. Monitoring the physical activity of children and young people is the main indicator of health sustainability. Basic physical activity calculated by means of simple indicators in representative samples of children and young people should be the basis for health analysis. The relationship between physical activity and a sedentary lifestyle seems to be insufficiently researched, which is particularly unfavourable, among others, due to the significant increase in the number of young people with obesity. The analysis of the number of steps provides an objective assessment of the current state of physical activity of children and young people and is the basis for promoting daily physical activity among young people.

Keywords: physical activity, accelerometry, children, young people, sedentary lifestyle.

Introduction. An important part of the people’s lifestyle is regular physical activity. A wide number of epidemiological studies have confirmed that regular physical activity has a positive impact on reducing mortality and incidence of various diseases [5,6,16]. Participating in physical activity is the basis for maintaining health of children and young people who are at a critical stage of their physical and mental development [29].

According to the World Health Organisation (WHO) documentation, with regard to children and young people aged 5-17, it is recommended to take up at least 60 minutes of daily Moderate-to-Vigorous Physical Activity (MVPA) for the purpose of meeting basic development and health needs [12, 13, 29].

Taking all levels of physical activity intensity into consideration, MVPA has been best studied and, on the basis of these studies, MVPA is considered to be essential for health promotion and disease prevention [19]. The analyses conducted suggest that 4/5 of the world's population of young people does not reach the MVPA [10] level recommended by WHO. The reason is that many children spend most of their time in a sitting position [8] and that this time has been longer for the past 10 years [21].

Monitoring physical activity by means of an accelerometer provides a reasonable compromise between accuracy and feasibility and increases the reliability of the daily MVPA level [11, 25]. As a result, the use of accelerometers has become a reliable and correct method for the purpose of estimating children's physical activity [15, 18].

Objective of this paper was to determine the level of physical activity of children and young people based on the MVPA index, number of steps, as well as sedentary time. This is aimed at analysing the young people's lifestyles and make them aware of whether the level of physical activity is sufficient, or whether action should be taken in order to make children and young people more active in this respect.

Study methods and structure. A diagnostic test of physical activity of pupils and students aged 7-18 was conducted in the School Complex in Zarzecze (Podkarpackie Province, southern Poland) in 2018, from April to June 2018, upon receipt of the written consent of the parents and the children themselves. 108 pupils and students (49 girls and 59 boys) took part in the study. Regular school attendance, teaching results, observations, interviews and teachers' opinions were taken into account as a basis for setting up the group. The criterion for a pupil or a student to be included in the project was regular attendance at all classes during the week. Within the framework of the study, anthropometric measurements were made, which took place between 8:00 and 10:00 am.  The ActiGraph WGT3X-BT accelerometer (Pensacola, USA), which is a 3-axis accelerometer, was used in this study. Nowadays, these accelerometers are used for the purpose of conducing analyses of physical activity levels [14]. In order for a given day of research to be included in the statistics, the accelerometer wearing time is assumed to be ≥ 500 minutes/day and ≥ 4 days as criteria for a valid 7-day data collection period [24]. According to the WHO guidelines, 60 minutes of MVPA per day [29] is a minimum.

The study subjects were instructed to wear the accelerometer for seven subsequent days, 24 hours a day. They were also informed that they must not use the accelerometers for spraying or water-related activities, as it must not come into contact with moisture. The ActiGraph data was analysed using Actilife 6.0 software (ActiGraph LLC, Pensacola, FL, USA). In addition, values of weight and height were measured and the Body Mass Index (BMI) was calculated by squaring the body size (kg / m²) BMI (kg/m²).

The following parameters were analysed: BMI, Sedentary, MVPA (Moderate-to-Vigorous Physical Activity) and number of steps.

Results and discussion. In table no 1, BMI is divided into four age groups. The average BMI value of the sample group was 20.45 (minimum: 13.8 – maximum: 30.7), which is a very good result in each age group. In comparison with the Raustorp study [20], the average BMI value was 16.10-20.00 (group aged 8-14). In Russia, the average BMI value of two sample groups (sports and non-sports aged 6-10) was between 14.9-17.6 [1]. With regard to young people (15-18 years old), the average BMI value was 20.52-21.92 [9].

Table 1. BMI divided into four age groups.

Source: Based on author's own research.

In table no 2, the sedentary index indicating the time spent in lying, sitting or standing position - without body activity - was presented, which was 1167.4 minutes per day on average (minimum: 951.3 – maximum: 1335.1). From the aforementioned result obtained, about 8 hours of sleep (1167-480=687 minutes) should be subtracted, which means that the sample group spent only 273 minutes on average during a day on being active (walking, running, doing exercises). It should be mentioned that this index is increasingly being analysed in various studies on the whole world. In Aggio and research collaborators study [2], sedentary time of children and young people (group aged 5-15) was 354 minutes. In the subsequent studies (group aged 8-15) this time was 471-559 minutes per day [3]. In turn, according to the studies carried out in Germany (group aged 9-14), the average sedentary time was 561 minutes. [23]. According to Pfeifer and Rütten [17], maximum 2 hours of sedentary time for children and young people aged 6 - 18 are recommended. However, it should be mentioned that sedentary lifestyle becomes intensified at the time of puberty. Therefore, this is the period during which we need to pay particular attention to make young people more active. Minimising sedentary lifestyle is of key importance in preventive health strategies aimed at dealing with obesity and chronic diseases in children and young people.

Table 2. Sedentary index divided into four age groups.

Source: Based on author's own research.

Table no 3 presents one of the most important MVPA indices. The average value is 56.7 minutes (minimum: 19 – maximum: 133.6). This value corresponds to the WHO recommendation, that is at least 60 minutes of physical activity a day. The lowest MVPA average is at the age of 13-15 years (46.5 minutes), while the highest at 16-18 years (82.3 minutes). In Baskin and research collaborators studies [4], the sample group (aged 12-16) had an MVPA index of 40.4 minutes. On the other hand, in Aggio and research collaborators studies [2], the average MVPA index was 33 minutes. In a large-scale study conducted in 2017 (N=4123 study subjects aged 5-17 years), the average MVPA time was 53.5 minutes [22].

In relation to children and young people, Moderate-to-Vigorous Physical Activity (MVPA) has a positive impact on their physical and mental health in the short and long term [7, 13], so the analyses carried out are especially important for analysing physical inactivity.

Table 3. Total MVPA index divided into four age groups.

Source: Based on author's own research.

In table 4, the number of steps were indicated. The average value in this table is 8347 steps (minimum: 2630 – maximum: 19132). The analysis carried out by Vincent and Pangrazi [28] was one of the first studies assessing a large group of pupils aged 6-12 (N = 711). As a basis for physical activity, the authors suggested at least 11 000 steps for girls and 12 000 steps for boys. On the other hand, Tudor-Locke and research collaborators [27], suggested at least 12 000 steps for children aged 6-11 for girls and 15 000 steps for boys and for young people aged 12-19: 10 000– 11700 steps / day [26]. By comparison, the studies conducted by Tudor - Locke [25] indicated that children and young people made 9000 steps on average.

Table 4. Number of steps divided into four age groups.

Source: Based on author's own research.

Conclusions. For many generations, there have been changes in the course of the population's somatic development and these changes have been steadily speeding up. They are called 'secular trends'. One of their signs is the acceleration of biological development and adolescence period. These changes are primarily related to the constantly improving social and economic situation and the improvement of the population's standard of living. These factors are, among others: change of eating habits, an improvement in environmental conditions, an increase in the level of education and better quality of health care. Monitoring the physical activity of children and young people is the main indicator of health sustainability. Basic physical activity calculated by means of simple indicators in representative samples of children and young people should be the basis for health analysis. The relationship between physical activity and a sedentary lifestyle seems to be insufficiently researched, which is particularly unfavourable, among others, due to the significant increase in the number of young people with obesity. The analysis of the number of steps provides an objective assessment of the current state of physical activity of children and young people and is the basis for promoting daily physical activity among young people.

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