Background
Among children and adolescents, there is a serious risk of obesity [
1], cardiovascular disease [
2], metabolic [
3], and mental disorders [
4]. Rapid decreases in physical activity (PA) occur during adolescence [
5‐
8] and continue later, in adulthood [
9,
10]. Similarly, there is a decline in level of vigorous PA [
11,
12] and growing lack of interest in physical education lessons in adolescence [
13]. Boys have been shown to be more physically active than girls during both school and weekend days [
14‐
16], while adolescents of both genders are less physically active on weekends than on school days [
17‐
19]. This is confirmed by results from Central Europe, with the most critical day for PA being Sunday, as shown in adolescents from Poland, the Czech Republic and Slovakia [
20].
The majority of adolescents in Central Europe do not meet the moderate-to-vigorous physical activity recommendation of 60 min a day or step count recommendations [
8,
21‐
25]. Indeed, in 2012, only 35 of 131 European studies reported that youth were meeting the daily PA recommendation [
26]. Given that PA in adulthood is linked to PA in adolescence, this period of life is critical for PA promotion [
27,
28]. Increase in PA among Central and East European adolescents is also essential because an alarming amount of time spent being sedentary was reported from these countries [
22,
29,
30].
Insufficient physical activity, together with excessive sitting time, is a leading risk factor for non-communicable diseases and has a negative effect on mental health and quality of life [
31]. Adolescents who maintain a high level of PA in their young adulthood are at significantly lower risk of cardiovascular disease and are more likely to maintain good mental health status compared to adolescents with consistently low PA [
32]. For these reasons, the at-risk adolescents typified by lack of PA, marked physical inactivity, and excessive sitting time deserve special attention. Therefore, we have long investigated the following research questions: what is the weekly composition of PA in adolescents with generally low levels of PA, and how should school environment reflect potential specific features of students’ weekly PA composition in the school lifestyle?
The aim of the present study was then to determine differences in the composition of weekly PA between less and more physically active adolescent boys and girls and to identify potential stimuli for change in lifestyle among adolescents at highest health risk.
Discussion
The key finding of the present study highlights the fact that the weekly composition of PA is analogous in more and less physically active girls and boys. This implies that girls and boys who accumulate less PA respond to varying in-school and out-of-school conditions on specific days of the week in a similar way to physically active adolescent populations. The lowest difference in daily step count between boys and girls with higher and lower PA was found on Mondays; efforts to decrease this difference even further might be especially important as a way to compensate for Sundays, as the most critical day with the lowest level of PA. The low level of PA on Sundays has been previously reported by numerous studies [
20,
38‐
41]. The unfavourable PA on Sundays in the least physically active adolescents has not been getting any better thus far. One of the main causes lies likely in the less tight daily schedule, compared with school days. School-based PA represents 33 and 34% of total daily PA in Polish girls and boys, respectively [
42], thus absence of this setting is to a large extent attributable for the low PA level on weekends. Extending the offer of popular organized physical activities, with competitions usually taking place on weekends, supported by successful interventions, could be beneficial. Increase in Monday PA in less physically active adolescents may also distort the consistently low level of PA among this population on other days of the week. These findings should be respected in the offer of physical activities for less physically active adolescents. This holds true for school programs, in-school extracurricular activities, comprehensive physical activity programs, but also for clubs and other institutions providing extracurricular physical activities. Such an approach would also require to develop a system of identification of at-risk adolescents, complemented by diagnostics of sport or physical activity preferences.
Mean daily step count on school days and weekends in less active girls equals 7717 steps/day (6040 steps/day at weekends), and in boys, 7707 steps/day (5821 steps/day at weekends); these low counts are alarming. Our study confirmed again that girls respond better to wearables than boys [
20,
43] (e.g. less missing data, interest in use of pedometers after the end of study period) and that the gender-differences in PA volume (as expressed by step counts) have been diminishing. According to [
44], the use of pedometers in less active adolescents might lead to an increase of roughly 2500 steps/day. In the current era of ubiquitous technologies, application of easy-to-use fitness trackers or mobile phone apps to track and motivate for PA could promote PA in adolescents [
45,
46].
Given recent trends in adolescents’ PA, one can infer that the most widespread recommendations of 10,000 steps/day [
47,
48], 10,000–11,700 steps/day [
34], 12,000 steps/day [
49,
50,
51], the 11,000 steps/day for both boys and girls promoted by our team [
41,
52,
53], or 13,000–16,000 steps/day focused on weight-reduction behaviours [
54], are not accepted well by adolescents with lower levels of PA. In Canada, Colley et al. [
50] suggested revising the recommendation from 13,500 to 12,000 steps/day among 6–19-years-old children and adolescents, which they found more appropriate benchmark for assessing the guideline of 60 min of daily moderate-to-vigorous PA. It needs to be further verified, if the recommended combination of goal-setting and walking exercise program [
55] works also for less physically active adolescents.
The pedometer-friendly value of 9000 steps/day, proposed by Adams et al. [
33], appears to be the most feasible for less physically active adolescents, while still being motivational. The recommended value of 9000 steps/day for adolescents is adequate given the number of <5000 steps/day as a step-defined sedentary lifestyle index for adults [
56]. Unfortunately, we lack evidence that would enable us to set a step-defined sedentary lifestyle index in children or adolescents. Moreover, it remains unknown if the finding of Anson and Madras [
57] – that university students with higher daily goals for steps reached higher step counts than those with lower goals – is applicable also to adolescents. We assume that feelings of satisfaction gained by meeting the 9000 as opposed to the 11,000 steps/day (which we observed in 13.4% of boys and 15.6% girls), could have a higher motivational effect, increasing daily PA and leading to a rise in the numbers of days when this recommendation is met.
Regardless of the specific daily step count recommendation, it is necessary to be aware of and respect geographic, socioeconomic, educational, national, and health specifics and sport preferences. The environment in Central Europe can be considered still acceptably walkable for adolescents, in spite of drawbacks related to transportation infrastructure and urbanism, such as heavy traffic, speeding, and lack of pedestrian-friendly crossings [
58]. Traditionally high rates of adolescents involved in organised leisure-time PA in Poland [
30] and the Czech Republic [
22] as well as in Eastern Europe (e.g. Estonia, Lithuania) [
21] are also a positive factor.
As there is a linear relationship between level of PA and adolescents’ health status [
59], physically active adolescents suffer from fewer psychosocial symptoms [
60], and as adolescents’ step counts decline as they grow older, less active adolescents are at high future risk of several diseases and medical conditions. At least it is positive, that the present study did not find a decrease in PA (expressed by steps/day) in group with the lowest PA level over the 8-year monitoring. School administration, in cooperation with parents and leisure-time institutions, including amateur sport clubs, should focus on less physically active adolescents in a similar manner to other socially marginalised and health-endangered populations, putting emphasis on the improvement of adolescents’ physical literacy [
61,
62] and more efficient use of information technologies for positive changes in their lifestyle [
44,
63]. In particular, prevention of cardiovascular diseases [
9,
64] and mental health promotion [
65] need to be prioritised. PA trends in representative samples of children and adolescents observed using simple indicators such as daily step counts are also essential in Central European countries. Awareness of these trends, as exists for example in Canada [
66], is crucial for the development of efficient health, school, and educational policies.
Strength and limitations
The eight-year monitoring period using the same methods under the consistent lead of the same research team is a strength of the present study. Achieving this will be more and more difficult in future studies, however, because of the rapid development and promotion of wearables and mobile technologies. The composition of weekly PA in adolescents with different level of PA, with special attention paid to adolescents at health risk, is much scarcer. The education effects of the research are inspiring for the adolescent physical literacy field because of the options for data analysis and feedback for participants provided directly by the Indares application. The main limitations of the present study include intentional quota sampling based only on type of school, where student teachers had their teaching practice, and size of the city. Due to the relatively small number of participants in each year of the research (182 to 253 per year), it was impossible to determine time trends in daily step counts. Moreover, we did not collect data on socioeconomic status or race/ethnicity. Even though Poland is a country with relatively small income inequalities (Gini coefficient = 0.28) [
67] and mostly homogeneous population [
68], lack of these nuisance variables could have affected our findings. Similarly, possession of more specific data on respondents PA (e.g. extracurricular sport or physical education lessons) could have better explained the weekly composition of adolescents’ PA.
It is likely that the findings on the weekly composition of adolescents’ PA are closely related to their education activities. Lower differences in step counts between groups with varying overall level of PA are perhaps related to increased education demands after the weekend. Adolescents’ higher PA on Fridays has been repeatedly observed throughout Central Europe (Czech Republic, Poland and Slovakia) [
20], and is probably linked to the end of the school week education process and subsequent decrease in school-related stress and school commitments. Traditional family activities on Sundays and preparation for school might be a factor in why adolescents’ PA is low on Sundays. Therefore, future research should focus on associations between weekly PA composition in adolescents by their overall level of PA and demands of the education process at various types of schools.
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