Physical activity of Czech adolescents : Findings from the HBSC 2010 study

and negatively related to health complaints and smoking (Iannotti, Kogan, Janssen, & Boyce, 2009). In addition, there is evidence that increased physical activity improves academic and cognitive performance (Strong et al., 2005; Tomporowski, Davis, Miller, & Naglieri, 2008). Numerous studies have documented factors associated with young people’s physical activity (Bauman et al., 2012; Ding, Sallis, Kerr, Lee, & Rosenberg, 2011; Haug, Torsheim, Sallis, & Samdal, 2010; Sallis, Prochaska, Taylor, Hill, & Geraci, 1999), suggesting that the key determinants include demographic factors Introduction


Introduction
Extensive reviews of the literature on children and adolescents indicate that moderate-to-vigorous physical activity (MVPA) improves both short and long term physical and mental health status as general health, bone health, health related quality of life and positive mood states have all been associated with higher levels of daily physical activity (Annesi, 2005;Hallal, Victora, Azevedo, & Wells, 2006;Iannotti, Janssen et al., 2009;Strong et al., 2005).Negative relationship between physical activity and obesity was also confirmed (Fleming-Moran & Thiagarajah, 2005).In early and mid-adolescence 1 , physical activity is related to self-image and quality of family and peer relationships 1 A thorough understanding of adolescence in society depends on information from various perspectives, including psychology, biology, history, sociology, education, and anthropology.Within all of these perspectives, adolescence is viewed as a transitional period between childhood and adulthood, whose cultural purpose is the preparation of children for adult roles (Larson & Wilson, 2009).In this publication we adhere to definition used by WHO as period between age 10 and 19.
(younger age, male), psychological factors (such as perceived barriers, competence and enjoyment), social factors (such as encouragement from parents, siblings and peers) and the physical environment (such as the availability of facilities and programmes).
Recommendations for physical activity at population level, for example in terms of intensity and duration, have been widely debated in recent years (Andersen et al., 2006;World Health Organization, 2010).Based on their extensive review of the literature, Strong et al. (2005) developed the recommendation that children participate in at least 60 minutes of moderate to vigorous physical activity daily2 .These recommendations are consistent with recommendations of governmental and professional organizations (Center for Disease Control and Prevention, 2000; Department of Health, Physical Activity, Health Improvement and Protection of the UK).Andersen et al. (2006) suggest an even longer duration of daily moderate intensity physical activity is necessary to affect the pattern of cardiovascular risk factors.As a secondary recommendation activities improving muscular strength, flexibility and bone health should be undertaken on two or more days a week are suggested (Department of Health, Physical Activity, Health Improvement and Protection of the UK, 2011;WHO, 2010).
The post-communist bloc countries (e.g. the Czech Republic) appear to have a tendency to replicate the "negative" health trends that had been previously witnessed in economically developed Western countries: a decrease in PA and an increase of overweight and obesity (Branca, Nikogosian, & Lobstein, 2007).Indeed, Central and Eastern European countries could learn from such "negative" Western European and global experiences (Knai, Suhrcke, & Lobstein, 2007).The adolescent population represents one of the most physically active subpopulations (Le Masurier et al., 2008).Monitoring the levels of PA together with motives to perform is critical for future programs aiming to enhance PA in youth and young adults in the Czech Republic and further afield in other Central and Eastern European nations that are in transition.

Aim
The aim of this study is to provide basic overview about moderate-to-vigorous physical activity, vigorous physical activity and motives to physical activity of Czech adolescents on the basis of gender and age group.

Sample and procedure
We used data from the Health Behaviour in Schoolaged Children (HBSC) study conducted in May-June 2010 in the Czech Republic.Self-completion questionnaires were administered in school classroom with requirements in terms of sampling, questionnaire items and survey administration being set out in a standardised research protocol.All of the questions used in the HBSC survey must have evidence of reliability and validity when used in multiple countries before they are considered for inclusion (Roberts et al., 2009).
From a list of schools based on information from the Institute for Information on Education, a contributory organization of Ministry of Education, Youth and Sport, 91 schools from all 14 regions of the Czech Republic were randomly chosen to create a representative sample.We contacted 91 schools, and 86 schools took part in our survey, representing a 94.5% school response rate.According to the protocol of the HBSC study classes from the 5 th to 9 th grades were selected randomly, one from each grade per school.We obtained data from 5,284 adolescents from the 5 th , 7 th and 9 th grade of elementary schools in the Czech Republic (response: 87%).Non-response due to absence was 13% (786 pupils).We did not compute how many of them was absent because of illness.For the purpose of the paper were analysed adolescents in the age of 11 years (n = 1,418), 13 years (n = 1,449) and 15 years (n = 1,518).The final sample consisted of 4,385 Czech pupils (48.5% boys) (Table 1).
Participation in the study was fully voluntary and anonymous with no explicit incentives provided for participation.Questionnaires were administrated by trained research assistants in the absence of a teacher during regular class time.Parents were informed about the study via the school administration and could opt out if they disagreed with it.Physical activity of Czech adolescents: HBSC 2010 study physical activity in their free time.For each reason please tick how important it is for you" with possible answers (1) very important; (2) fairly important; (3) not important for the following reasons: (1) to have fun, (2) to be good at sport, (3) to win, (4) to make a new friends, (5) to improve my health, (6) to see my friends, (7) to get in good shape, (8) to look good, (9) I enjoy the feeling of using my body, (10) to please my parents, (11) to be cool, ( 12) to control my weight, and (13) it is exciting.

Statistical analyses
To provide basic overview about HBSC data, frequencies and proportions according gender and age groups were calculated for all indicators.Chi-square test of independence was used to provide basic comparison on basis of gender and age groups.

Moderate-to-vigorous physical activity
Our findings show that substantial part of boys and girls are not participating in MVPA as recommended (Table 2).Sufficient daily MVPA is varying according age group from 24.8% to 29.5% among boys and from 14.3% to 23.3% among girls.It means that more than 3 quarters of adolescents did not reported recommended level of daily MVPA.In addition with increasing age the involvement in MVPA among girls became significantly lower (χ 2 = 38.765,df = 14, p < .001).Although there are also some age variations in MVPA among boys, the differences between age groups are not statistically significant (χ 2 = 12.112, df = 14, p = .597).This leads to gender differences with increasing age.While in 11 years age group the differences between girls and boys in participating MVPA were not significant (χ 2 = 4.948, df = 7, p = .666),in older age groups boys attended significantly more MVPA than girls (13 years: χ 2 = 40.161,df = 7, p < .001;15 years: χ 2 = 49.179,df = 7, p < .001).

Vigorous physical activity
According our findings, portions of adolescents which reported vigorous daily activity from 7 to 4 times per week varied according age group and gender from 23.7% to 47.4% ( The possible answers were "every day, 4 to 6 times a week, 2 to 3 times a week, once a week, once a month, less than once a month, never".2. Outside school hours: "How many hours a week do you usually exercise in your free time so much that you get out of breath or sweat?" The possible answers were "none, about half an hour, about 1 hour, about 2 to 3 hours, about 4 to 6 hours, about 7 hours or more".

Motives for physical activity
Motives for physical activity were assessed using a question in HBSC study consisting of 13 items examining why young people undertake leisure time physical activity (Wold & Kannas, 1993)."Here is a list of reason that some young people give for taking part in between age groups among boys were not significant (χ 2 = 16.830,df = 12, p = .156).VPA was more occurring among boys compared to girls.The difference was significant at age of 11 (χ 2 = 32.134,df = 5, p < .001),age of 13 (χ 2 = 50.071,df = 5, p < .001)and also at age of 15 (χ 2 = 68.141,df = 5, p < .001).
Similarly to MVPA and occurrence of VPA there is pattern of significant decrease of duration of VPA with increasing age (χ 2 = 19.093,df = 10, p = .039)(Table 4).For example, at age of 11 more than 35% of girls have at least 2 hours of VPA per week.This number goes down at age of 13 to more than 33% to finish at about 28% at age of 15.In addition decrease in duration of VPA is significant also among Czech boys (χ 2 = 31.165,df = 10, p < .001).It seems that major shift in duration of VPA among boys occurs between age 11 and 13.For example at least 4 hours of VPA was reported by 14.2% of boys at age 11, 9.1% at age 13 and 9.8% of boys at age 15.Similarly to occurrence of VPA among adolescents gender differences between boy and girls were found also for duration of VPA.Boys were involved in longer VPA compared to girls and the difference was significant at age of 11 (χ 2 = 17.240, df = 6, p = .008),age of 13 (χ 2 = df = 6, p < .001)and also at age of 15 (χ 2 = 87.814,df = 6, p < .001).

Motives for physical activity
Our study also focused on the motives for physical activity among Czech adolescents (Table 5).According reports both form girls and boys, most popular motives among Czech adolescents are "to have fun", "to make a new friends", "to improve my health", "to be cool" or "to see my friends".On the contrary, motive "to win" was reported as not important by the most of girls and boys.When comparing the preferences of particular age groups, motives like "to have fun", "it is exciting", "to look good" or "to see my friends" becoming popular in older age.On the other hand, motives like "make new friends", "to be good at sport", "to improve my health", "to please my parents" or "to control my weight" are less important for older adolescents than for the younger ones.Motives "to be good at sport" and "it is exiting" are much more important for boys compared to girls.On the contrary, motives "to be cool", "to see my friends" and "to make new friends" are more important for girls.

Discussion
This study provides basic overview about moderate-tovigorous physical activity, vigorous physical activity and motives to physical activity of Czech adolescents Table 2 Over the past 7 days, on how many days were you physically active for a total of at least 60 minutes per day?According our findings substantial part of boys and girls are not participating in MVPA as recommended.This is in line with previous other findings from the Czech Republic (Frömel, Pelclová, Skalik, Nováková-Lokvencová, & Mitáš, 2012;Vašíčková, Frömel, Groffik, & Chmelík, 2013) and Central European region (Bergier, Kapka-Skrzypczak, Bilinski, Paprzycki, & Wojtyla, 2012;Biddle et al., 2009;Hamar, Biddle, Soos, Takacs, & Huszar, 2010;Hoffmann, Bryl, Marcinkowski, Strazynska, & Pupek-Musialik, 2011;Soos et al., 2012).Although the minimum recommended daily step count is not achieved by a non-negligible part of the Czech adolescent population, they are still considered active walkers (Vašíčková, Frömel, Groffik, & Chmelík, 2013).According to Beets, Bornstein, Beighle, Cardinal, and Morgan (2010), boys and girls from European and Western Pacific region had We also found that with increasing age the involvement in MVPA among girls became significantly lower.PA promotion in adolescent girls might be enhanced by offering them their preferred activities, such as dance, aerobics, sport games (Sigmund, Sigmundová, Frömel, & Vašíčková, 2010).With regards to actions to address the gender differences in PA among adolescents Vašíčková, Groffik, Frömel, Chmelík, and Wasowicz (2013) recently published an interesting study.Their aim was to assess whether 4-week monitoring with pedometers can influence differences between the level of PA amongst adolescent girls and boys.As result of the four-week intervention the difference in the overall PA of adolescent girls and boys diminished, together with the difference between school and weekends among girls.The use of pedometers, motivational recording brochures and an Internet programme for maintaining PA for a longer period, supported the continuance for movement of an active and healthy lifestyle among girls significantly more than their use among boys.Another recent study with promising results uncovered the patterns of moderate-to-vigorous physical activity in normal weight and overweight/ obese children before, during, and after school lessons (Sigmund, Sigmundová, Šnoblová, & Gecková, 2014).They found that adding one physical education lessons or an equivalent amount of MVPA to the daily school routine appears to be a promising strategy to effectively increase daily MVPA, particularly among overweight/ obese girls.
On the other hand, boys usually prefer sports games (Sigmund, Frömel, Klimtová, & Tomik, 2000).However, despite the popularity of sports games, in boys, the current study found a negative secular change in time spent playing games.Achieving sufficient PA in adolescence appeared to be most beneficial in enhancing adult PA e.g.adolescents' (boys) participation in ball games increased their participation in ball games in adulthood (Tammelin, Nayha, Hills, & Jarvelin, 2003).
Particular age groups differed in some of the motives for PA.For example, motives like "to have fun", "it is exciting", "to look good" or "to see my friends" becoming popular in older age.On the other hand, motives like "to be good at sport", "to improve my health" or "to please my parents" are less important for older adolescents than for the younger ones.In addition, motives "to be cool", "to see my friends" and "to make new friends" are more important for girls.As the children grow the peer pressure increases and social motives strengthen.Especially girls appear to be more influenced by social motives.Camacho-Miñano, LaVoi, and Barr-Anderson (2011) recommend making physical activity enjoyable for girls by increasing the choices and offering a wide range of non-competitive and innovative activities.Social motivation could be the way to reduce difference in level of physical activity between female and male adolescents (Litt, Iannotti, & Wang, 2011).
It was expected and also in line with other previous studies (Iannotti et al., 2013;Litt et al., 2011;Wold & Kannas, 1993) that achievement is more important for boys and also is increasing with age.It is important to note that the study was conducted on the sample from a post-communist European country where adolescents report less health and social motives for PA and more motivation oriented to achievements than adolescent in Western Europe or North America (Iannotti et al., 2013).

Strengths and limitations
It is important to consider certain limitations and assets of this study.An important strength is that we collected relevant data from a nationally-representative sample of adolescents from two countries from the age groups relevant for establishing health-related behaviour.A limitation of our study is that the results are based on self-reported data.However, self-reporting has been shown to offer satisfying reliability in terms of health-related behaviour.Moreover, personal motivations are usually based on self-report and the items used to assess physical activity have been shown to have reasonable reliability and validity (Prochaska, Sallis, & Rupp, 2001).The questionnaires were filled out anonymously and with assurances of confidentiality.The main limitation, however, is the cross-sectional design of our study, which makes it impossible to formulate conclusive statements about causality in our findings.They therefore need to be confirmed in studies with a longitudinal design.

Conclusion
A substantial part of boys and girls are not participating in MVPA as recommended.In addition with increasing age the involvement in MVPA among girls became significantly lower.Girls differ in motivation for physical activity from boys.Better understanding of the motives for physical activity as well as gender-and age-based differences in physical activity levels can significantly contribute to better planning of national and local intervention promoting active living.
Physical activity of Czech adolescents: HBSC 2010 studyTable 3How often do you usually exercise in your free time so much that you get out of breath or sweat?How many hours a week do you usually exercise in your free time so much that you get out of breath or sweat?

Table 3 )
. It means that more than 50% of adolescents are not involved in VPA for more than half of the week.When comparing the age groups results differ for girls and boys.We can see statistically significant decrease of VPA occurrence among girls from age 11 to age 15 (χ 2 = 66.186, df = 12, p < .001).For example, every day VPA occurrence among girls decreased from 15.9% at age 11 to 11.4% at age 13 and to 6.2% at age 15.Differences in VPA occurrence

Table 1
General description of the study sample

Table 5
Motives for physical activity of Czech adolescents † Physical activity of Czech adolescents: HBSC 2010 study significantly more steps per day than their counterparts from the U. S. and Canada.