An all-Poland survey of physical activity and sedentary lifestyles for middle school, high school and university students

INTRODUCTION

Since the 1990s, a sedentary lifestyle has been more frequently observed in most countries, together with insufficient or nonexistent engagement in physical activities [1, 2]. According to experts, only one third of adolescents are estimated to undertake enough physical activity to ensure normal physical, mental and emotional development [3]. A UNICEF report has demonstrated that Polish adolescents aged 11, 13 and 15 years have higher BMIs compared to adolescents from economically developed countries; with this increase doubling during 2001 to 2010 [4]. On the one hand, this trend has arisen from modern-day developments linked to changing lifestyles, as well as ignorance of the necessity of physical activity for normal human development.
World Health Organisation (WHO) recommendations concerning levels of physical activity in children and adolescents point out that 60-minute daily levels of ‘moderate to vigorous physical activity’ (MVPA) are beneficial during adolescent development [5, 6]. In response to unsatisfactory physical activity levels in all global societies, the American College of Sports Medicine has likewise issued calls for achieving health and wellness through increasing physical activity [7]. Engaging in an active lifestyle and maintaining a normal body mass is the most effective means of preventing many modern-day diseases [8, 9], inter alia obesity and associated metabolic disorders, atherosclerosis [10], hypertension and cardiovascular disease [11]. Obesity is also linked to various types of cancer risk, including that of the colon, breast, endometrium, liver, kidney, oesophagus, stomach, pancreas and gall bladder [12]. Current studies show that the most effective way of dealing with obesity is through appropriate dieting and increased energy expenditure through physical activity [13, 15]. For these reasons, educational and health programmes need to be introduced to ensure adolescents are made fully aware that physical activity and a healthy diet are required for a healthy life during all of its stages [16-18].

STUDY AIMS

To establish how frequently the Polish study subjects (i.e. students) took part in PE (Physical Education) lessons and after-school movement activities, and how often they opted for sedentary activities.
To investigate the relationship between physical activity, TV watching and time spent on computers with the risk of overweight and obesity in these subjects.

STUDY METHODOLOGY

Students selected randomly from middle schools, high schools and universities in Poland were surveyed in 2011. A total of 15,868 study subjects were chosen from 569 schools in 379 local districts. Of these, 3,548 students from middle schools, 4,423 from high schools and 5,595 from universities were qualified for statistical analyses. Roughly 78% of all respondents correctly completed their questionnaires. The number of females and males were 1,742 and 1,806 in middle school, 2,275 and 2,148 high school, and 3,315 and 2,280 at university.
Middle and high school students were asked to fill in a questionnaire which had been devised by Poland’s Chief Sanitary Inspectorate (GIS) and based on previous GSHS studies (Global School-based Student Health Survey). Educational staff units of the State Sanitary Inspectorate conducted the survey. Questions concerned lifestyle behaviours.
Random sampling for the survey was performed in two stages: first by school, then by class. Subjects from the chosen classes who anonymously completed the questionnaire were enrolled for the study. These people were sampled according to randomly selected institutions taken from the Ministry of Education’s database of schools registered as of 30 September 2008. The schools thus surveyed were grouped by the population of their district, the type of community (i.e. urban, rural), the province (i.e. voivodeship, there being 16 of these in Poland) and type of institution (middle school, high school, technical school). Schools were randomised using the STATISTICA 12 system. The questionnaire for university students was slightly different, in that was conducted electronically by means of a website set up by the Institute of Agricultural Medicine in Lublin. Data on types of university and each student’s area of residence were collected, permitting sampling to become stratified as it was being performed, thereby allowing appropriate corrections to be made for specific groupings. Surveying the students in this way may have introduced certain systematic errors involving the reliability and completeness of responses. The correction procedure therefore used an ‘over-sampling’ process and excluded those questionnaires containing any errors or repetition, i.e. structural sampling adjustments were made.
In order to verify the questionnaire data, it was compared with data from Poland’s Central Data Statistical Office (GUS), where significant differences were found. It was thereby decided to correct the student sampling by ‘over-sampling’ a relatively small portion, whereby its structure fairly closely agreed with the categories of provinces (voivodeships), gender and age as found in the nationwide GUS data. Such corrections did not remove all differences, but did make the sampling significantly more representative, essentially a compromise between representativeness and numbers. Undertaking any further corrections would have lead to further reductions in the target sample size, thus worsening the ability for testing statistical hypotheses.
The paper-based responses were entered into a central database, thus allowing for analysis by the STATISTICA 12 system. Testing the dependence of variables on a discrete scale for multi-field tables was performed by the χ2 test. For continuous or sequential variables, the Kruskal-Wallis test or variance analysis test was used, depending on the nature of the variable (e.g. distribution compliance). Statistical significance was taken as p not greater than 0.05.

RESULTS

The survey data gathered from middle and high school students showed they most often undertook 2 to 5 hours of PE lessons weekly, as declared by half of these subjects (Table 1). In middle and high school subjects with excessive body mass, the highest rates of overweight and obesity were observed for those engaging in only 1 to 2 hours of physical activity per week (Table 2). University students demonstrated a greater unwillingness to take part in any obligatory PE lessons compared to their younger counterparts, with 54% declaring no participation whatsoever (Table 1). The highest rates of overweight and obesity occurred in those students spending only one hour per week on movement activities (Table 2).
This study demonstrated that normal body mass was dependent on frequency of participation in PE. The highest rates of optimal BMI were observed for those engaging in 5 to 7 hours of physical exercise weekly (Table 2). A decided majority of respondents did not take part in any extra after-school activities. Answers from the younger students on how frequently they engaged in defined sports were found to be unsatisfactory. In their free time, every fourth student from middle or high school spent one hour a week on a chosen sport (Table 1). This attests to a weak commitment in adolescents to engaging in movement activities, both at and after school. University students most often spent their free time with peers. It was however satisfying that subjects spent even five hours per week on movement and games. It was also found that 35% and 33% of middle and high school students, respectively, helped their parents with domestic chores. Even so, such help was limited to 1 to 2 hours weekly (Table 3).
Sedentary behaviour increases with age. This is supported by our study, where 54% of university students participated in no PE lessons. Furthermore, up to 84% did no extra movement activities organised by their institutions. In their free time, 35% abstained from doing any sport (Table 1), and on a weekly basis, half the subjects took no part at all in any games or movement activities with their peers. Similarly to their younger counterparts, 28% of these students most often devoted 1 to 2 hours per week to domestic chores (Table 3).
Subjects were asked how they most often commuted to school and how much time this took. This significantly affected estimates of their daily physical activity. Walking to school was undertaken by 41%, 36% and 25% of middle school, high school and university students, p (χ2) < 0.001. Correspondingly, 82%, 65% and 43% declared that commuting to school took 20 minutes (Fig. 1.). Subjects most often commuted to school by public transport, at rates of 41%, 46% and 45%, respectively. Commuting by bicycle was not popular, with only 5%, 3% and 1% doing so, p (χ2) < 0.001. More time was decidedly spent on activities associated with less energy expenditure, as demonstrated by commuting time being most often one hour per week (Table 3). More than a third of subjects in each grouping most frequently spent their free time watching TV or being on computers (Fig. 2).
It was often seen that overweight and obesity rates were directly related to increases in the time spent watching TV and being on computers. This was observed for each age grouping. Of those middle school (13%), high school (14%) and university (14%) students who were overweight, it was observed that 6%, 5% and 6% with excessive body mass most often spent 5 to 6 hours per day watching TV or being on computers. The corresponding obesity rates for spending this amount of time on such sedentary activities were 2%, 1% and 2%. The highest rates of subjects with normal BMI were those who spent two hours daily watching TV or being on computers (Table 4).

DISCUSSION

Like adults, adolescents increasingly demonstrate low levels of physical activity. This leads to higher rates of overweight and obesity, which in turn increase the risk of modern-day diseases. A 2013 HSBC study (Health Behaviour in School-Aged Children) conducted in Poland, showed that the recommended daily levels of one hour’s physical activity was achieved by only 28% of adolescents aged 11 to 12 years, 23% of those aged 13 to 14 and 13% in the 15 to 17 age group [19]. A study conducted in north-east Brazil on secondary schoolchildren aged 14 to 19 years, demonstrated that only 50% of subjects took part in PE lessons totaling over 300 minutes per week [20]. Different means of commuting to school influence overall activity levels [21, 22]. This all-Poland study shows that public transport dominates in this respect. It is estimated that it takes around 20 minutes for students to travel to school. Those commuting on foot constitute 41%, 36% and 25% of middle school, high school and university students, respectively. Only 5%, 5% and 1% opt to commute by bicycle. The HBSC study showed a journey time of 15 minutes in 60% of subjects, with the majority (47%) walking to school. Like our survey, the HSBC study showed a low rate (5%) of commuting by bicycle [19].
For the majority of children and adolescents, PE lessons at school constitute their only organised means of engaging in physical activity. Many international organisations for physical activity, and UNESCO, argue that physical education is an integral part of schooling and should be mandatory for at least one hour daily for all students [23]. In Poland, PE lessons are obligatory for a total of four hours weekly for elementary and middle school students and three hours for older students [24].
This study has demonstrated that only half of middle and high school students take part in PE lessons for 2 to 5 hours weekly. The Brazilian study on students aged 14 to 19 years shows only 35% engaging regularly in PE lessons [25]. Woynarowska found that almost every third pupil abstains from all or nearly all PE lessons [26]. In order for the needs of children to be satisfied in terms of performing regular physical activity at school, a diverse choice of such activities should be offered and tailored to the child’s stage of development, especially at the youngest ages. An important part of overall physical activity is having a diversity of movement and sporting activities chosen freely by students apart from PE lessons. This nationwide study found that every fourth middle and high school subject is engaged in a sport during their free time for one hour weekly, whereas every fifth subject never did this at all. Indeed, GUS data confirm our findings, where 30% of elementary schoolchildren undertake at least one hour of physical activity weekly [27]. During free time however, physical activity was not a popular option. In the majority of children, movement activities were limited to obligatory PE at school, which is itself inadequate. Nevertheless, it is encouraging to see that 25% and 20% of middle and high school students engage up to five hours weekly in games and movement games in the company of their peers. Furthermore, every third of these students does two hours of domestic chores per week.
As they mature, young people are less physically active. Our study shows that 54% of students do not take part in PE lessons, 84% abstain from after-school movement activities and 35% never undertake any sports at all. When comparing the free time university students actively spend with their peers, they diverge from the younger subjects of our study, and most frequently (15%) spend 1 to 2 hours weekly on chosen physical activities in the company of their peers. They also willingly help with domestic chores.
Subjects preferred spending 3 to 4 hours per day watching TV or being on the computer as opposed to engaging in sports or other forms of physical activities. This was observed in 35%, 39% and 37% of middle school, high school and university students. Numerous international recommendations stress that sedentary activities (e.g. ‘screen time’) should be confined to two hours daily [28, 29]. Studies conducted from 2002 to 2010 in 30 selected countries showed that watching TV declined only slightly. The largest decreases in weekday and weekend viewing were seen in males from the Ukraine, Latvia, Estonia, Russia, Norway and the US. For females, the greatest differences were observed in Finland, Norway, Ukraine, Wales, Estonia, Italy, Latvia, Spain and the US. Nonetheless, there has been a massive rise in computer use by both females and males in all the surveyed countries [30]. Brazilian studies show that 69% of teenagers spend weekday time watching TV and being on computers, whilst 80% do so at weekends [31]. Similar studies on Polish and Czech secondary school students have likewise found that more time is spent on screen time at weekends compared to weekdays [32]. A survey by Jodkowska on Polish 13-year-olds demonstrated that the most free time is spent watching TV, followed by being on the computer, jointly amounting to four hours per schoolday and six hours daily at weekends [33]. Our work has also shown that time spent on sedentary activities is closely related to how parents supervise their children; more supervision corresponds to less screen time. Furthermore, Fenner has demonstrated that those overweight teenagers motivated by their parents to pursue an active lifestyle do indeed engage in more physical activity [34].
Shortfalls in physical activity constitute an independent risk factor for obesity [35]. A Chilean study on teenagers showed that those who were obese and spent excessive time watching TV and being on computers (≥ 2 hours daily) had low levels of physical activity [36]. A Brazilian survey of teens 14 to 17 years old found that overweight rates were directly related to low levels of physical activity and increased screen time [37]. This is confirmed by our study, where the highest rates of overweight and obesity were observed in students who abstained from PE lessons and indulged in 5 to 6 hours per day of screen time. US studies on secondary school students showed that subjects spent at least 5 hours per day watching TV, which was linked to increased obesity [38]. A study from Cracow on middle schoolers who spent excessive time surfing the Internet found that 7% had become addicted to the practice [39]. An interesting solution is to take advantage of both the Internet’s popularity and its usefulness as a source of educational knowledge concerning healthy lifestyles, as has been exploited by Park et al. [4]. By such means, these researchers developed a ‘Teen-Friendly Health Education Program’ available on social media and networking service ‘Facebook’. Thus, by exploiting the benefits of the Internet, suitable texts can be promoted to help teenagers make informed choices for adopting healthy lifestyles.

CONCLUSIONS

Students, especially at university, are somewhat poorly committed to doing PE lessons and other forms of movement activities, preferring to engage in mainly sedentary activities.
Increased overweight and obesity rates found in subjects are directly related to engaging in physical activity less frequently, but also to increased hours spent watching TV and being on computers.

ACKNOWLEDGEMENTS

Editors would like to acknowledge the invaluable assistance of Mr. Scott Thompson in the preparation of the final version of this article.

DISCLOSURE

Authors report no conflict of interest.

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AUTHORS’ CONTRIBUTIONS

PWB, WŻŚ, AW prepared the research concept and design of the publication. TB, WŻŚ, MŁG and KJ collected data. PWB, TB, KW, MŁG and KJ analysed data. PWB and CW wrote the article. AW critically reviewed the publication. HK finally approved the publication.