Rapporter
IDROTTSVETENSKAP
2012
Nr. 2
GÖTEBORGS UNIVERSITET
Institutionen för kost- och idrottsvetenskap
Swedish young peoples´
lifestyles with focus on
physical (in)activity and
overweight/obesity - a review of the research
literature
Göran Patriksson
Table of contents
General introduction to the problem area .................................................................... 2
Aim of the project ......................................................................................................... 3
Definitions and measurement problems of central concepts ....................................... 3
Physical activity recommendations and guidelines for youth ................................... 3
Definitions of physical and physical fitness .............................................................. 4
Measurement issues ................................................................................................ 5
Recommendations of children’s and adolescents´ dietary intake ............................ 5
Definitions of overweight and obesity ...................................................................... 6
Sedentariness .......................................................................................................... 7
The International context ............................................................................................. 7
Health Behaviour in School-aged Children (HBSC) study................................... 7
The 1997/1998 HBSC survey: Exercise and leisure-time activities ................ 8
The 2001/2002 HBSC survey: PA and Sedentarism........................................ 9
The 2005/2006 HBSC survey: Health outcomes, behaviours and risks ....... 11
The EYHS study .................................................................................................... 12
The literature search strategy .................................................................................... 13
The Swedish national context .................................................................................... 14
Physical activity and physical fitness ..................................................................... 15
Participation in organised and informal sports (and tracking tendencies) .............. 18
Overweight and obesity ......................................................................................... 21
Target groups for the interviews in the next phase of the projects ............................ 25
References ................................................................................................................ 26
1
General introduction to the problem area
The health benefits related to physical activity in all ages have more and more gained
acceptance and recommendations of physical activity (PA) have been developed for
maintaining and improving health in most countries. Physical activity is an important
factor, although difficult to measure, for young peoples´ health development. It is
documented that children and adolescents who participate at higher levels of physical activity are less likely to display risk factors for early mortality, cardiovascular disease, type 2 diabetes mellitus, hypertension, stroke, metabolic syndrome, some cancers, osteoporosis and obesity in youth and adults. Even higher levels of physical
activity, particularly vigorous physical activity, have stronger correlations with lower
frequency of overweight and obesity, type 2 mellitus and lower levels of central adiposity (waist circumference). In addition, physical activity seems to have an influence
on academic performance, self concept and psychological/mental health.
It is increasingly more understood that these diseases and problems start their development in childhood and teenage years. What young people do in these years
may set the pattern for their future life as it is common that individuals establish many
of their lifestyle choices as they pass through their adolescent years (Hallal, Victora,
Azevedo, & Wells, 2006; Salmon, Booth, Phongsavan, Murphy, & Timperio, 2007;
Sisson & Katzmarzyk, 2008).
The prevalence of overweight and obesity has increased dramatically worldwide during the last decades in all ages and was/is considered as a serious public health
problem, even named as the “obesity epidemic”. It is estimated that – in general – the
prevalence of overweight in children and adolescents is 20%, one third of them being
judged as obese. Childhood obesity has adverse psychological, social and health
effects in early as well as in later life, especially when it comes to cardiovascular disease and metabolic syndrome and associated mortality. Furthermore, prevalence
levels have been rapidly increasing for more than two decades together with changes
in dietary and physical activity patterns. These unfortunate trends have also been
combined with an unequal distribution across socio-economic categories (Cattaneo
et al., 2010; Rokholm, Baker, & Sørensen, 2010).
Another - geographical - trend is that there is generally lower levels of overweight
found among children in central and eastern Europe, a higher prevalence of overweight in the southern countries of Europe, with the Scandinavian and western countries (Great Britain is an exception) in between (Brettschneider & Naul, 2007; Lobstein & Frelut, 2003).
Assuming unchanged relationships between obesity, associated health problems and
mortality, such a prediction would cause big public health problems that could threaten several sectors in society and may also reduce the hitherto increasing life expectancy chances (Rokholm et al., 2010).
However, since the early 2000s there have been several studies around the world
indicating that the rapid increase of overweight and obesity among children seems to
have levelled of and in some countries even minor decreases have been reported
(Rokholm et al., 2010; Waling, Lind, Hernell, & Larsson, 2011) These tendencies
could perhaps be traced to the growing interest by international organisations (such
as WHO) and national governments to handle this phenomenon concerned with its
future impact on health on both individual and population levels (Daugbjerg et al.,
2009; Monteiro & Victora, 2005; WHO, 2010).
2
Aim of the project
A major issue in most modern societies is an increasing gap between different social
groups, which also affect the possibilities to live an active and healthy lifestyle. A
large number of reports also depict a growing amount of children and adolescents in
Europe as a high-risk group with regard to a healthy development. This group is often
characterised as too fat and physically unfit and has additionally adopted unhealthy
nutritional patterns as part of a sedentary lifestyle, which in turn will lead to negative
consequences for the individual development and the social health care systems.
The detailed relationship between physical activity, fitness, fatness and health in adolescence is still lacking and remains to be clarified (Moreno et al., 2007). This (and
other) research projects are needed in order to try to deepen our knowledge of these
relationships.
We know, however, that all groups in society are not affected to the same degree by
this unhealthy development. There are clear differences according to socio-economic
status, gender, age, geographical location between and within countries and cultural
background of the individuals. Despite the existing knowledge about these differences, we can not yet explain the interplay between these (and other) factors and
their impact on active and inactive lifestyles. Therefore the common aim of this European project, which is lead and coordinated by Hans Peter Brandl-Bredenbeck at
University of Paderborn, Germany and includes sub-projects in Flandern, Belgium
(Jan Seghers), Great Britain (Kathleen Armour), Greece (Konstantin Kougioumtzis),
Italy (Attilio Carraro) and Sweden (Göran Patriksson), is (1) to know more about
which factors foster and hinder the development of an active and healthy lifestyle and
(2) if these factors are the same in different groups with regard to socio-economic
status, gender, age (children versus adolescents), geographic (rural – urban) and
ethnic-cultural background. The specific aim of this report is to systematically go
through appropriate recent Swedish research and other research with relevance to
Sweden (mainly from 2004 and onwards) in these areas and to find out the most vulnerable subgroups among young people: the target group for the next phase of the
project; a qualitative approach with group/focus interviews and in depth interviews.
Definitions and measurement problems of central concepts
In this section some of the most central concepts for the study will be discussed. This
is important since various definitions are used in different national contexts and in
cross-cultural/comparative studies, which can make it difficult to do comparisons and
to draw conclusions from data across countries, but also from studies within the
same country. Another problem is – independent of which definitions used – how
these concepts (for example physical activity, physical fitness, overweight/obesity
and dietary intake) are measured: which methods are used. These kind of problems
are also important since most countries have developed, based on expert committees, guidelines for young people’s physical activity and food habits (Armstrong &
Welsman, 2006; Brettschneider & Naul, 2007; Cattaneo et al., 2010; Waling, 2011).
Physical activity recommendations and guidelines for youth
The first formal physical activity guidelines for youth were formulated by the American
College of Sports Medicine (ACSM) 1988 (see Armstrong & Welsman, 2006). The
ACSM based their proposal on guidelines for adults and recommended 20-30minutes
of vigorous exercise per day for children and adolescents.
3
In 1993 an International Consensus Conference (ICC) presented the following recommendations based on a review of scientific literature:
All adolescents should be physically active daily or nearly every day, as part of play
games, sports, work, transportation, recreation, physical education or planned exercise, in the context of family, school and community activities.
Adolescents should engage in three or more sessions per week of activities that last
20 minutes or more at a time and that require moderate to vigorous levels of exertion
(Sallis & Patrick, 1994).
Although other guidelines were published, the ICC-recommendation was adopted in
many countries worldwide.
In 1998 a British guideline sharpened the time recommendation for physical activity
(of at least moderate intensity) to 1 hour per day (Biddle, Cavill, & Sallis, 1998), a
recommendation that has been accepted in many countries, including Sweden
(Becker et al., 2004). For small children younger than six years old physical activity
health-related guidelines recommend engagement in at least two hours of physical
activity a day, half in structural and the reminder in unstructured free play (Haerens et
al., 2010).
There have, however, been critical voices to these types of guidelines (see Twisk,
2001), which are considered too generally formulated, because there are different
patterns of relationship for different health outcomes. (Andersen et al., 2006) have
indicated that 60 minutes of daily physical activity seem to be too little to prevent a
clustering of cardiovascular disease risk factors including excess of fatness in children and adolescents. In their study they reported that 90 minutes of moderate to
vigorous physical activity was necessary to have such effects, results that are mainly
supported by (Ortega, Ruiz, & Sjöström, 2007), who concluded that 60 minutes or
more of daily physical activity, if enough vigorous activity is accumulated during such
a period, have strong correlations with lower proportions of overweight and lower risk
of central adiposity among young people.
Definitions of physical activity and physical fitness
An often used definition of physical activity is “a complex set of behaviours that encompass any bodily movement produced by skeletal muscles that result in energy
expenditure” (Caspersen, Powell, & Christenson, 1985, p. 126). Physical activity encompasses all bodily movements independent of aim or context including for example play, hobby activities, games and sports. The total energy expenditure is the sum
of the following items: basal metabolism which contribute about 60% of the total daily
energy expenditure, the effects of the digestive system (about 10%), and the average
physical activity level (30%).
Another closely related concept is physical fitness, which has been defined as “a set
of attributes that people have or achieved that relates to the ability to perform physical activity” (Caspersen et al., 1985, p. 126). Physical fitness is usually seen as a set
of different components. These include body composition, cardio-respiratory endurance/fitness (CRF), muscular endurance, muscular strength, balance and flexibility
(A. Westerståhl, 2003). Physical activity and physical fitness have a close and complex interrelation to each other (mutually affecting), but there is far from a one to one
relationship, because there are a lot of other variables (i.e. food, biological maturity,
4
illness, drugs, genetic structures and environmental factors) that can influence and/or
confound the relationship.
Measurement issues
There are several methods to measure physical activity. The assessment techniques
must in the first place be socially acceptable, should not burden the child or adolescent with cumbersome equipment and should as little as possible influence an individuals´ normal physical activity pattern. As an ideal the instrument should be able to
measure the frequency, intensity, duration and mode of activity (Armstrong & Welsman, 2006). Up to now, no single method/instrument can asses all these dimensions
in a highly reliable and valid way, but if using complementary methods/instruments it
is possible to increase the assessment qualities.
Different techniques may therefore be measuring different dimensions of physical
activity and this could, as least partly, explain for the often weak relationships between different assessment techniques. By these reasons the habitual physical activity patterns among European youth, measurement issues must be taken into account and the results evaluated in the context of the methodology used.
There are several methods to measure physical activity. The most common ones are
self-reporting subjective instruments like questionnaires and physical activity diaries.
However, there exist also more “objective” methods such as pedometer, accelerator,
heart rate registration and doubly labelled water (DLW). All methods/instruments
have their pros and cons concerning validity, reliability costs and suitability for young
people. It is important to conclude that no method is perfect for all aspects of physical
activity and for all ages. For example, questionnaires provide a cheap method and
are mostly used to measure physical activity among large scaled samples (such as
the European WHO study: “Health behaviour in school aged children (HBSC) study”),
but it has been found that the validity/reliability is rather low, especially among children when measuring physical activity of moderate intensity (Patriksson & Stråhlman, 2006).
Activity diaries should be avoided before the age 15-16 years and self administrated
questionnaires are not suitable below the age of twelve. On the other hand several of
the “objective” methods are time consuming, because they must be individually calibrated, do not function well for certain activities (cycling, water activities etc). DLW is
recognised as the reference method or “gold standard”. It is, however, costly and requires advanced equipment. As Armstrong and Welsman (2006) note: “Studies (using DLW, author’s comment) generally have very small sample sizes and no information is provided on the participants´ physical activity pattern, therefore making it
impossible to identify activity of moderate or vigorous intensity” (p. 1073). It could be
added that all “objective” methods are unable to identify what type of physical activity
that is performed and in what social context (school, sport club, community, family,
transportation, alone versus together with others etc). This inability is a serious drawback that is seldom mentioned in the studies using these kinds of methods.
Recommendations of children’s and adolescents´ dietary intake
In most European countries some kind of recommendations exist concerning the
consumption of various categories of foodstuff for particular age groups and that give
desired values for the percentage distribution of energy-supplying foodstuffs
5
(Brettschneider & Naul, 2007). Dietary intake of young people is a key determinant of
growth and development throughout the childhood and adolescent years.
Together with the other Nordic countries (Denmark, Finland, Iceland and Norway)
Sweden has recommendations on dietary intake with the aim to provide a base for
good health. The guidelines are based on current scientific knowledge with respect to
energy and nutritional demands for various groups of the population, but take also
food habits into account and provide some recommendations on meal planning as
well as physical activity (Enghart Barbieri & Lindvall, 2005; Weber et al., 2004).
How to assess the dietary intake among young people? The assessment methods
are usually categorised into retrospective and prospective methods and can cover
shorter or longer periods of time. Examples of retrospective methods are the diet history interview (DHI), 24 hour recalls and food frequency questionnaires. Prospective
methods are performed by the respondent each day in close connection to the consumption of food and beverage (Waling, 2011). The use of different measurement
methods makes it difficult to compare results from different studies. A recent review
of the literature concluded, however, that the most accurate dietary assessment
method for children 4-11 years old was a 24 hour recall repeated at least three times
and including parents as informants. For adolescents 16 years and older DHI was the
most valid method when compared with doubly labelled water (Burrows, Martin, &
Collins, 2010).
Definitions of overweight and obesity
An often used definition of overweight and obesity is the abnormal or excessive fat
accumulation that may impair health (WHO, 2000). The most common and easiest
way of classifying adults into underweight, normal weight, overweight and obesity is
to calculate the person’s body mass index (BMI) and use specific cut-off values. Adult
BMI 25.0-29.9 is considered as overweight and ≥ 30.0 as obesity. These values give
useful information of increased health risks on a population based level. However,
these BMI cut-offs can not be used in children since natural age and gender-specific
variations in body composition take place during different maturation phases. So far,
there is no worldwide accepted way of classifying young people into overweight and
obesity. The most commonly used categorization in Europe is the International Obesity Task Force (IOTF) definition, where the corresponding cut-offs as for adults are
used, but adjusted for age and sex (Cole, Bellizzi, Flegal, & Dietz, 2000; M. G. Neovius, Linne, Barkeling, & Rossner, 2004; Waling, 2011). Other commonly used cutoffs regard the 85-90th or 95-97th percentile of the BMI distribution as thresholds to
overweight and obesity respectively. But since the percentile values differ within these intervals in various European countries (and countries outside Europe) it is difficult
to make comparisons (Brettschneider & Naul, 2007; Waling, 2011).
Measurement of height and weight can also be done in different ways of objectivity
from using standardized equipment to subjective self-reports from either youngsters
themselves or their parents. Other measures are skin-fold thickness and different
kind of non-anthropometric based methods. Altogether, these methodological issues
must be taken into consideration when data from different studies are interpreted.
Overweight and obesity can mainly be seen as an imbalance between energy intake
and energy expenditure. Some individuals are partly predisposed to overweight and
obesity due to their genetic background and may respond differently to milieu factors
like dietary habits and physical activity. Some researchers propose that energy intake
6
is the primary cause, but there is little empirical evidence that overweight and obese
young people have a higher energy intake compared to their normal weight peers.
Brettschneider and Naul concluded that “…in spite of the abundance of food available and contrary to popular assumptions, young people adolescents do not eat too
much and their total energy intake has not increased over time” (Brettschneider &
Naul, 2007, p. 12). The total energy expenditure seems therefore at present to have
a higher explanatory power (Rodríguez & Moreno, 2006; Waling, 2011).
Sedentariness
A growing number of researchers think that increasing sedentary behaviour among
young people is a major determinant of reducing energy expenditure in a situation
where energy intake does not have changed. Sedentariness is usually described as
“sitting behaviour” in front of TV, video screens and computers, but also a lot of other
activities producing low energy expenditure as studying, talking with fiends and passive transportations with different vehicles (Rey-López, Vicente-Rodríguez, Bueno, &
Moreno, 2011).
Media consumption seems to play an important role in European adolescents´ daily
life, but look like to be stable over time (Brettschneider & Naul, 2007). There are also
contradictory findings between sedentary behaviours and physical activity that makes
it difficult to draw simple and straight forward conclusions (Todd & Currie, 2004). It is,
however, impossible to not include sedentariness as an important factor when analysing physical activity, energy intake and overweight/obesity among young people.
Inequality in health related issues
According to WHO and most national health policy documents (including Sweden) all
individuals should have access to the best possible health care irrespective of race,
gender, religion, political standpoint, economic condition or social status. In reality
this vision is not always fulfilled and there is a huge mass of data showing that inequality in health related matters exist – to different degrees – both in Europe and the
rest of the word. Consistent relationships have been found between health outcomes,
including its correlates such as physical activity, sport participation and overweight/obesity, and socio-economic status (SES), age, disability, gender, ethnicity
and geographical location (Currie et al., 2008; Whitehead & Dahlgren, 2006).
The International context
Health Behaviour in School-aged Children (HBSC) study
The Health-Behaviour in School-Aged Children (HBSC) study is a cross-national
project in collaboration with the WHO Regional office for Europe aiming to increase the understanding and to gain new insights into health behaviour, lifestyles and their context in children and adolescents. Taking a social than a purely
biomedical perspective, HBSC data focuses not only trends over time both within
and between countries but as well the relationships between health, health behaviour and factors affecting them. On of the earliest international reports was
published 1996 with data from the 1993-1994 survey, while the next international
report was announced year 2000 including information from the 1997/1998 survey Since then two more reports have been issued with data from the 2001/2002
7
and 2005/2006 surveys respectively. Additionally a plethora of articles with international comparison or country specific focus have been published.
The 1997/1998 HBSC survey: Exercise and leisure-time activities
The 1997/1998 HBSC survey questionnaire included among others demographic
characteristics, general health and wellbeing as well as health-behaviour such as
exercise and eating patterns and leisure-time activities (Currie, Hurrelmann, Settertobulte, Smith, & Todd, 2000). The focus areas included school experiences,
relationships with parents, SES and body image, while countries from all parts of
Europe, from Canada and from the United States of America participated. The
sample of the survey were young people aged 11, 13 and 15 and was drawn using cluster sampling with the class as the primary unit. The total number of respondents in Sweden was 3802 individuals, that is 1986 boys and 1816 girls or
1216 11-years-old, 1357 13-years-old and 1151 15-years-old individuals (Hickman, Roberts, & Gaspar, 2000).
A section of the 1997/1998 HBSC survey examined engagement in physical activities that are both beneficial during youth and adolescence and likely to encourage a lifelong active lifestyle. To estimate weekly cardiovascular activity
questions focused weekly leisure time frequency and duration of vigorous physical activity defined as “equivalent to at least slow jogging, which might expected
to leave the participant feeling out of breath and sweaty” (Hickman et al., 2000, p.
75). Furthermore, screen-based inactivity has been obtained using daily duration
of TV watching and weekly duration of computer game playing.
According to the results some overall trends can be seen across most countries.
Regular exercise is more common among boys than among girls and declines
with age especially for girls. Gender differences seem to be largest in Greenland,
Lithuania and Greece and especially in the age of 15 as girls exercise half that of
boys. Additionally, boys are more likely than girls to exercise more hours per
week at all three ages in all countries, while pupils in Germany and Austria are
more likely to report exercise of four hours or more. Regarding TV watching, in
most cases less than half of pupils reported a daily TV watching of 4 hours or
more. In the vast majority of cases boys are also more likely than girls to watch
television four hours or more daily. Large gender differences can be shown in
matters of weekly computer game playing, as more boys reported an engagement of four hours or more. Furthermore, further results and analysis indicated
positive correlations between TV watching and junk food consumption as well as
negative correlations between TV watching and participation in Physical Activity.
Swedish pupils’ answers are summarized in table 1.
Table 1. Swedish school-aged children’s exercise and leisure time activities (%)
11-years-old
Activity
15-years-old
Girls
Boys
Girls
Boys
Girls
Boys
twice or more
59
77
64
87
55
71
two hours or more
44
57
53
67
53
68
four hours or more
18
19
23
28
19
25
Weekly computer game four hours or more
6
28
7
39
3
34
Weekly exercise
Daily TV watching
Frequency or Duration
13-years-old
8
playing
As shown in table 1, Swedish boys are more physically active than girls in all the
three age groups. The biggest difference is among the 13 years old adolescents.
There are only small differences in TV watching (boys looking slightly more), while
boys spent much more time than girls in playing computer games, especially the 13and 15 years old groups, where there the differences are slightly over 30%.
According to the results, students in families with one or more cars are more likely to exercise. It seems that having access to leisure facilities and parents with
higher SES has an impact on pupils’ participation in physical activities (Hickman
et al., 2000). The 1997/1998 HBSC survey contained multiple indicators on SES
such as number of family cars, existence of own bedroom, participation in vacation with the family (not connected to parental occupation). The overall analysis
indicated a positive correlation between family affluence (material wealth) with
more regular exercise and more fruit eating. However, unhealthy behaviours
such as smoking did not patterned with the SES of the family.
The 1997/1998 HSCB survey highlighted the effect of school and parents in PA
activity patterns indicating that students report more physical activity if they are
satisfied with the school, they are involved in setting rules at school, thy feel supported by teachers and other students and the expectations by parents and
teachers are low.
The 2001/2002 HBSC survey: PA and Sedentariness
The 2001/2002 HBSC study was conducted in 35 countries of the Americas and
Europe and highlighted young peoples physical, emotional and psychological
aspects of health and the influences of family, schools and peers as well as socioeconomic and developmental factors. About 1500 respondents in each of the
three age groups were targeted in each country utilizing a clustered sampling
procedure with the school or the class as the primary unit. In relation to the previous HBSC report more clearly a salutogenic perspective on health is obvious,
while an emphasis is given to principles of empowerment, young peoples own
perspectives and definitions of their emotional and physical well-being and the
subjective aspects of health. As Currie et all put it: “subjective indicators have
objective behavioural consequences” (Currie et al., 2004, p. 55).
Within this survey, PA is associated with a corresponding increase in fitness
which influence not only sleep quality but good health and life quality as well. Additionally, a shift from at least 30 minutes to at least 60 minutes a day as the recommended PA can be seen as most young people are already active a day while
the concern is altered to the increasing levels of obesity. Thus, the levels of PA
activity are assessed utilizing MVPA (moderate to vigorous physical activity)
measure using questions connected to the past seven days or to a typical or
usual week. The MVPA is consistent with the definition of PA as presented previously in this report (see Roberts, Tynjälä, & Alexander, 2004), while the cut off point
of meeting the recommendations is set to minimum five days per week MVPA of at
least one hour.
The overall results indicated that about one third (34%) of all young people report
physical activity of one hour or more of at least moderate intensity on five or more
9
days a week. Despite differences between age groups some countries are consistently in the top (Canada, England etc.) or in the bottom (Belgium – Flemish – Estonia, France, Italy etc.). In all countries less girls that boys meets the recommendations, while the gender differences exceeds 10% in more than half of the countries,
and only 5% and 1 % in Italy and Netherlands respectively. In the vast majority of
countries the proportions of meeting the recommendations decline with age. In Sweden the decrease of requirement fulfilment is higher between the ages of 11 and 13
than between 13 and 15, while in Greece the decrease is vice versa. France, Netherlands, Switzerland, FYROM and US show no decline with age (Hickman et al., 2000).
Sedentary behaviours in the 2001/2002 survey have been obtain utilizing questions
on daily hours of TV watching, computer use and homework with a cutting point fοr a
high level at 4 hours or more, 3 hours or more and 3 hours or more respectively. Furthermore, patterns are differentiated in weekdays and weekends. In the majority of
countries slightly more boys than girls report a higher TV watching in all groups. The
absolute gender differences rarely exceed 10%. The largest difference between the
ages occurs in Austria, France and Germany where weekend use increases by about
20%. Regarding computer use, a gendered pattern is evident as more boys than girls
report a high use. Gender differences are lowest in Canada and USA, and highest in
Denmark and Finland where boys’ percentages are five or six times higher than girls.
Computer use increases mostly between the ages of 11 and 13. The average of
young people who exceed the cutting point for high levels of homework is approximately 19%. Regarding homework, there is a remarkable difference between Finland
and Greece as 2% and 60% of young people respectively do their homework for tree
hours or more during weekdays. Summarising the findings the correlation of PA and
sedentariness shows geographical and gender variations while the highest significant
correlation was 0.17. For girls a significant association is evident between TV use
and PA. For boys the correlation between PA and sedentariness is non significant.
The data connected to Swedish pupils are presented in table 2.
Table 2. Swedish young people’s PA and sedentary behaviours
11-years-old
Activity
15-years-old
Girls
Boys
Girls
Boys
Girls
Boys
Weekly Physical Activity Mean number of days
with one hour or more
4.0
(4.3)
4.4
(4.3)
3.8
(3.5)
3.9
(4.2)
3.6
(3.2)
3.9
(3.9)
Meeting MVPA recommendations (%)
36.4
(33.1)
43.8
(43.8)
29.5
(26.9)
31.2
(40.9)
26.3
(22.3)
32.7
(35.3)
four hours or more (%)
11.7
(22.1)
13.2
(26.5)
19.5
(27.2)
18.6
(30.5)
19.8
(23.4)
24.3
(28.0)
Weekday Computer Use three hours or more (%)
5.0
(6.2)
19.3
(17.2)
9.2
(8.1)
30.6
(21.8)
9.4
(7.7)
31.6
(23.6)
Weekday homework
4.1
(17.2)
4.0
(13.0)
6.4
(24.6)
7.8
(15.3)
15.2
(26.2)
7.0
(14.6)
Weekday TV watching
Measure
13-years-old
three hours or more (%)
Note: HSBC average in parenthesis
The physical activity level of Swedish adolescents is rather close to the average of
the participating countries. Compared to earlier results from HBSC the differences
10
between boys and girls have decreased (can partly be due to that the questions are
differently formulated). Swedish young people watch TV to a much lesser extent than
the average value, but 13- and 15 years old youngsters (particularly boys) are much
more frequent computer users than most other young people in corresponding ages.
There is a strong contrary trend concerning time devoted to homework. Swedish children and adolescents spent very little time to homework compared to the mean value.
The 2005/2006 HBSC survey: Health outcomes, behaviours and risks
The 2005/2006 HBSC survey is consistent with previous themes of the project, while
a focus is given on health inequalities on the basis of gender, age, geographic and
socioeconomic level. The sampling strategy as well as the sample size within the
2005/2006 survey follows the logic of previous HBSC surveys, while five more countries have been included. The total number of respondents in Sweden was 4392
individuals that is 2179 boys and 2213 girls or 1513 11-years-old, 1353 13-yearsold and 1526 15-years-old individuals (Currie et al., 2008).
The HBSC 2005/2006 survey international report (Currie et al., 2008) contains selected overview data, while details on both national and international levels can be
found in numerous scientific peer-reviewed articles, factsheets, briefing papers and
other reports. Furthermore, an increased attention has been given not only to methodological refinement, but to conceptual development, theory advancement and research dissemination as well. More specifically, the previously developed HBSC
Family Affluence Scale (FAS) intakes a central position indicating a composite measure on parents’ occupational status, family affluence (material conditions of the
household) and family poverty. A FAS score 1 is connected to low affluence, while 2
and 3 refer to middle and high affluence respectively.
The next table highlights HBSC FAS scores of the Active Lifestyles project countries
Table 3. Family affluence
FAS 1 (low)
FAS 2 (medium)
FAS 3 (high)
England
8
31
60
Sweden
7
38
56
Belgium (Flemish)
10
42
47
Germany
13
40
47
Italy
21
45
33
Greece
25
47
28
As is seen in table 3, where the countries that are involved in this project are taken
out separately, Sweden has a high FAS score and comes very close to England.
Belgium (Flandern), Germany, Italy and Greece are placed lower with regard to FAS
scores.
Within the 2005/2006 HBSC survey, physical activity has been obtained through the
number of days per week with at least 60 minutes of moderate to vigorous physical
activity (MVPA). Regarding sedentariness, the weekday television watching is highlighted. Furthermore, overweight and obesity is emphasized utilizing the BMI index.
11
Comparisons between the 2001/2002 and the 2005/2006 survey can cautiously be
done in aspects of PA activity as the former adopted 60 minutes or more MVPA for
five days per week while the later was based on recommendations of MVPA for at
least 60 minutes or more every day. The same regards even matters of daily TV
watching as the former survey used a cut of point of four hours ore more per day,
while a cut off point of two hours or more per day is used in the later survey.
The answers of Swedish young people’s are summarized in table 4.
Table 4. Swedish young people’s health behaviours and health outcomes
11-years-old
Activity
Measure
Weekly Physical Activity Meeting MVPA recommendations (%)
two hours or more (%)
Boys
Girls
Boys
Girls
Boys
20
(22)
23
(30)
14*
(15)
21*
(25)
10
(12)
11*
(20)
26
48*
(60)
Total HBSC average
Overweight or obesity
Reported weight / height
and BMI calculation (%)
Total HBSC average
15-years-old
Girls
Total HBSC average
Weekday TV watching
13-years-old
20
55*
(63)
66
(69)
61
8
(12)
16
67
(70)
59
(67)
70
9
(16)
9*
(10)
14
68
13*
(16)
13
61
(69)
9*
(10)
15*
(17)
13
Note: HSBC average in parenthesis, * indicates significant gender differences
Swedish children and adolescents reach to a little lower extent the recommended
time of physical activity than the average school children in this investigation. There
is also a diminishing tendency of physical activity related to higher ages. Girls are
less active than boys and only 10% of the 15 year old girls live up to the physical activity guideline of at least 60 minutes of moderate to vigorous activity every day.
Swedish young people watch TV to a somewhat smaller extent than their counterparts in other countries. Concerning overweight and obesity Swedish youngsters
have slightly lover levels of overweight/obesity than the HBSC average, especially
among the youngest age group. There are significant sex differences in the two oldest groups (more boys than girls were overweight/obese).
The EYHS study
The European Youth Heart study (EYHS) is an international school-based project
addressing the prevalence and causes of CVD risk factors including PA in children
aged 9 and 15 years (Riddoch et al., 2004). The aim was to establish relationships
between personal, environmental and lifestyle influences (Riddoch et al., 2005). A
sample of at least 1000 boys and girls from each one of the four participating countries 1 was collected. According to Armstrong and Welsman (Armstrong & Welsman,
1
Originally four countries participated (Denmark, Estonia, Norway and Portugal). Later on some other
countries entered e.g. Spain, Iceland and Sweden
12
2006) EYHS is one of the most substantial studies using accelerometer. Data from
the project has been published widely with national and international focus. Within
section representative articles are presented.
Andersen et al (2006) used data from 1732 9 and 15 years old school children from
Denmark, Estonia, and Portugal to describe PA and physical fitness. According to the
results, PA activity in girls is consistently lower than in boys at both ages and in all
three countries. However, significant differences existed between countries as Danish both boys and girls showed lower levels of PA.
Nilsson et al (2009) used data from 1327 9 and 15 years old children and adolescents from Estonia, Norway and Portugal to compare self reported MVPA and objectively measured MVPA. According to the results, the two methods differ significantly
regarding after school outdoor play, sports participation and MVPA time. Furthermore, self reported sedentary behaviour correlates are likely to disagree with self reported PA correlates. Furthermore, gender differences are significant as girls spend
less time in MVPA and more time in sedentary behaviours than boys do at both 9
and 15 years of age. The gender specific as well as the total MVPA is decreasing,
while time in sedentary behaviour is increasing with the age.
Riddoch et al (2004) published data related to 2185 9 and 15 years old children and
adolescents from Denmark, Estonia, Norway and Portugal. According to the results,
boys were generally more physically active than girls. The same pattern was evident
even in terms of the time engaged in moderate activity in both 9 and 15 years of age.
Additionally, more boys and girls met the health-related recommended level of PA at
the age of 9 than the age of 15. More specifically, the average daily MVPA in 9 years
old boys and girls was 192 (66) and 160 (54) minutes/day respectively, while the corresponding data in 15 years old children was 99 (45) and 74(32). At the age of 9,
97.4% of boys and 97.6% of girls met the recommendations, while at the age of 15
the only 81% of boys and 62% of girls did the same.
Vimaleswaran et al (2010) publish data related to 2062 children and adolescents
from Denmark, Estonia, Norway and Portugal. According to the results, PA in 9 and
15 years old boys was 745 (11.6) and 550(17.9) counts/minute respectively, while
the corresponding data for 9 and 15 years old girls was 617(8,9) and 452.7(101) indicating gender differences and a PA reduction over the years.
The literature search strategy
A systematic literature review approach consists of four areas: a) problem definition,
b) search strategy, c) study evaluation and d) data extraction (Badger, Nursten,
Williams, & Woodward, 2000). Regarding problem formulation, PA activity is the
main concept that has been established and defined earlier in this report. Furthermore,
it can be argued that physical or cardiorespiratory fitness, sedentary behaviour and
physically inactivity have an affinity with PA. Additionally, it seems that studies focusing
overweight/obesity contain often descriptions of physical activity patterns. Thus the
overall problem of this review is connected primarily to PA and complementary to physical fitness, cardiorespiratory fitness, sedentary behaviours, physical inactivity and
overweight/ obesity. Furthermore, three inclusion criteria was established, the first connected to studies published since year 2004, the second associated to young peoples
from primary to secondary school age and the third regarding peer-reviewed contributions.
13
Searching for a combination of “physical activity”, “adolescen* OR child*”2 and
“Sweden OR Swedish” in the main body of articles resulted in 79 to 109 hits in
SPORTDiscus, Academic Search Elite or ERIC. In MEDLINE and ISI Web of
Knowledge the hits were between 247 and 324 (see table 5). Refining the search in
SPORTDiscus, Academic Search Elite and ERIC using “physical activity” as a keyword, resulted in fewer hits. In MEDLINE via Ebsco, MEDLINE via PubMed and ISI
Web of Knowledge the refinement concerned “physical activity” as words in the title
because keyword-search were not supported. Further refinement by selecting only
peer reviewed accounts resulted in fewer hits in the first three databases, while the
later three databases do not include this use. Additionally, the hits connected to a
full text service were more limited. However, hits with no full text support could be
accessed via the journal site or in print form. In conclusion, articles referring to
“physical activity” in the text are much more than those connected to “physical activity” as part of a more indicative index such as keyword or word in the title. It is
obvious that articles targeting primarily overweight and obesity are many considering some aspects of physical activity as well. On the contrary, articles focusing first
and foremost PA are not so many.
Table 5. Children and Adolescents Physical Activity related publications in Sweden between 2004 and 2011
Hits
Peer-reviewed
Full text
All fields
Keyword
All fields
Keyword
All fields
Keyword
SPORTDiscus
79
20
79
20
58
15
Academic Search Elite
109
38
106
37
58
17
ERIC
109
34
106
36
60
15
All fields
Title Word
All fields
Title Word
All fields
Title Word
MEDLINE via Ebsco
247
115
-
-
95
40
MEDLINE via PubMed
324
19
-
-
-
-
ISI Web of Knowledge
160
47
-
-
-
-
As it can be seen in table 5, the sample of the relevant articles is between 79 and
160 articles, while the 247 and 324 hits in MEDLINE seem to indicate even books
etc. The evaluation of the abstracts of the 160 hits resulted in the articles which are
included in the present report.
The Swedish national context
In this section recent (mainly from 2004 to 2011) empirical research in Sweden about
physical activity, physical fitness and overweight/obesity and closely related areas
will be reviewed.
2
Star (*) to capture all suffixes e.g. adolescen-ts, adolescen-ce
14
Physical activity and physical fitness
How was the situation about 2004, where this review will approximately start? At that
time a similar EU-financed project was launched in Sweden (Patriksson & Stråhlman, 2006). The authors concluded about physical activity among children and
youth in Sweden. “In summary, these studies indicate on one hand that during the
covered time sport club participation increased – especially among girls – but on the
other hand that the number of inactive young people in sports appears to have increased. However, there are large variations among the studies reviewed, regarding
the proportion of young people that reach the recommendations of PA. The deviations may partly depend on which recommendations one is referring to (the demands
of what is satisfactory PA differ), which age groups are studied and which methods
are used to measure PA. The proportion not achieving the recommendation(s)
seem(s) to range from about two-thirds to one third in total. In certain subgroups the
results can vary to a very considerable extent from very high to very low PA”
(Patriksson & Stråhlman, 2006, p. 4) .
What has happened during the last seven years since the above mentioned review
was done? The literature search show that about 15 publications (not including the
HBSC project publications already discussed in this report) have appeared in peerreviewed journals with Swedish data during this period of time. Of these publications
a great majority was related to physical activity and only a few referred to physical
fitness. The studies include different age groups from preschool children to older
teenagers, but also adults in studies of tracking3 (Telama, 2009).
From a methodological standpoint the investigations have large variations in design
and measurement methods. Most of them are cross-sectional (one study uses historical data – over 50 years old – to compare with more current data), some are followup studies and a few are “pure” longitudinal studies: following the same individuals
over a long period of time. There exist no studies with national representative samples. Some studies have applied random sampling techniques, but on a local level
(for example a town). Generally the samples are rather small, especially when “objective” measures, such as pedometry and accelerometry, are used.
Dencker et al (2006) studied the daily physical activity among children aged 8-11
years. The study was done in Malmö, using the pupils who were enrolled in the
Bunkeflo study (a longitudinal study estimating the effect of daily physical activity).
However, only about half of the children, 248 (140 boys, 108 girls), took part in this
study. Physical activity was measured with accelerometers. Children were instructed
to wear the accelerometers for 4 days. The aim of the study was to measure the
amount of physical activity and estimate the proportion of children who reached the
recommended health related physical activity level(s). The results showed that the
mean daily activity was higher (22%) in boys than in girls. All children fulfilled for
moderate physical activity for 60 minutes or more per day. Ninety-two percent of the
boys and 86% of the girls performed vigorous activity for 20 minutes or more per day.
These proportions are a bit higher than in other studies using the same measurement
techniques (Riddoch et al., 2004) and much higher than studies where one applied
3
Defined both as a tendency of individuals to maintain their rank or position within a group over time
and the ability to predict subsequent observations on the basis of earlier values.
15
subjective methods (Currie et al., 2008). Possible explanations to the very high percentage of children who reached the recommendation may be the high drop- out frequency with elements of selection effects and that the whole group of pupils who participated lived in residential areas in the city of Malmö with a low proportion of immigrants and diverse ethnic background. By such reasons one can conclude that this
sample is representative neither for Malmö nor for Sweden. The results from this
study (and others) – again – raise the question of how relevant the current physical
activity recommendations are for particularly young children.
In another study by Dencker et al (2010) of 468 young children (6-7 years of age),
the purpose was to investigate the cross-sectional relationship between accelerometer-measured daily physical activity (both volume and intensity) and VO2 peak by a
direct measurement from a maximal treadmill exercise test. They found that the
amount of physical activity was associated with aerobic fitness, albeit weakly, in boys
(physical activity variables could explain 2-8% of the variance). No such uniform relationship was detected in girls.
The positive health effects of reasonably high levels of physical activity in early childhood seem to have emphasized the importance to know if these activity levels
change or remain rather stable. The limited knowledge about the determinants of
stability of activity in children was the reason behind the study of (Nyberg, Ekelund, &
Marcus, 2009). They examined the stability of physical activity in 6-10-year old children with a median duration of follow-up of 1.5 years. Accelerometers were used to
measure physical activity for 7 consecutive days. Baseline physical activity was significantly correlated with physical activity at follow-up (r = 0.59), with a stronger correlation for boys than for girls. High physical activity levels were more stable ((r = 0.74)
than low activity levels (r = 0.55). Physical activity at follow-up was explained by
physical activity at baseline and season (r2 = 0.46), whereas BMI SDS at follow-up
was explained by BMI SDS at baseline and age (r2 = 0.90). The results of this study
suggest that physical activity levels are fairly stable in children between 6 and 10
years of age. Interestingly, high levels of activity were more stable than low levels.
This may then indicate the importance of public health strategies to increase the
overall levels of activity in young children so that they can maintain high levels of
physical activity during childhood.
Public health programs and interventions can be designed in many ways and executed in one or more arenas. Sollerhed and Ejlertsson (Sollerhed & Ejlertsson, 2008)
argued that the school and its physical education program, in spite of the reduced
time in general in later years, is an important part of the society’s responsibility to
train and socialise its youth to be physically active. Therefore the purpose of this
study was to assess whether a school-based 3-years intervention program in primary
school with expanded physical education lessons was effective in increasing children’s physical capacity and in preventing excessive weight gain in children. The
study comprised 132 children, 73 boys and 59 girls at baseline 6-9 and in follow-up
9-12 years old, attending two different schools with similar size, appearance and
structure in a rural area in the south of Sweden. The norm school followed the stipulated curricular time, one to two lessons (40 minutes each) a week, while the intervention school increased it to four lessons. Most of the physical fitness tests used
were taken from the EUROFIT test battery. A physical fitness index was constructed
on the basis of the 11 tests.
The intervention had a positive effect .Which school the children attended was shown
to be decisive for the positive changes in the physical index, while the baseline BMI
16
ratio was not. The number of children who had an increase in BMI was higher in both
schools, but a lower increase could be seen in the intervention school. The limitations
of the study should, however, be considered. The small sample together with the lack
of information of socio-economic status limited the possibility to generalize the results. The authors´ conclusion was still:
“…our intervention study indicated that expanded PE-lessons could increase physical
status among both overweight and normal weight children. However, the dose of
physical activity in the physical education setting must be higher than 40 minutes a
day to reduce weight gain” (Sollerhed & Ejlertsson, 2008, p. 106).
Raustorp and co-workers have done a series of studies of pedometer-determined
physical activity using both cross-sectional data (different cohorts) over time and longitudinal data. In a study of time trends of physical activity in 7-to 9-year old Swedish
children, physical activity increased from year 2000 to 2006 (Raustorp & Ludvigsson,
2007), in contrast to the general secular trend in the world reporting of a decline in
the level of physical activity. In a tracking study (a 5-year follow-up), Raustorp,
Svensson and Perlinger (2007) explored tracking of pedometer-determined physical
activity in relation to BMI and sport club training. From the first study in 2000 consisting of 326 boys and girls 12-14 years of age they managed to identify 97 adolescents
who also participated in investigations 2003 and 2005, where the researcher used
the same methodology and instruments as in the first study. The main findings were
that physical activity seems to track lowly to moderately during adolescence and the
highly significant decrease seen in boys during early adolescence seemed to level
out in the later teenage years. Girls´, on the other hand, physical activity (steps/day),
with an exception in the baseline values, was slightly higher than the boys and the
decline in physical activity was much lower. In addition, youth training in sport clubs
maintained a higher level of pedometer determined physical activity throughout the
adolescent years. The shortcomings of this study are small not random samples
gathered in overall middle class dominated communities and from a generalisation
point of view geographically narrow.
In another study Raustorp and Ekroth (2010) made comparisons between two crosssectional cohorts of adolescents 13 to 14 years of age carried out 2000 (n = 235) and
2008 (n = 270). Data was collected with the same protocol and identical procedures
at the two occasions. Physical activity as average steps per day was stable in the
2008 cohort in comparison with the data from the 2000 cohort in both girls and boys.
This stable level of physical activity after a period of eight years is in opposition to
common consensus suggesting a decline of physical activity among young adolescents. The results are, however, in line with Raustorp and Ludvigsson (2007), but
also with a Danish study (between 1997/1998) and 2003/2004) of 8-to 10-year old
children (Möller, Kristensen, Wedderkopp, Andersen, & Froberg, 2009). The
Raustorp and Ekroth (2010) study has the same limitations as the other studies (see
above) conducted by this research team.
How is the physical activity level among older adolescents in Sweden? There is only
two studies published (F Rasmussen, Eriksson, Bockedal, & Schefer-Elinder, 2004;
M. Westerståhl, Barnekow-Bergkvist, & Jansson, 2005) during the time period covered (2004-2011). From earlier research in Sweden (Berggren, 2001; Bergren, 1998)
we know that girls were more physically active in leisure time than boys at low intensity level, whereas the opposite was the case at higher intensity levels. This study
followed 751 secondary schools pupils (15/16 year of age) in west Sweden for three
years. It was also found a significant difference among girls studying at theoretical
17
school programs compared to those in practical programs: to the advantage of pupils
at theoretical who were much more physically active in leisure time. No such difference was found in boys. In this study only one third of the pupils reached the recommendation from Sallis and Patrick (1994) to be moderately active 30 minute/day with
more intensive physical activity three times/week. It should be observed that school
PE was not included. In the follow-up, when the pupils were 18/19 year of age, similar physical activity patterns could be seen, but girls studying at practical programs
slightly increased their activity level, whilst boys went in the opposite direction.
Rasmussen et al (2004), in the Stockholm area, also found that 15-year old boys
were much more physically active than girls. Regarding vigorous physical activity half
of the boys were active 0.6 hours per day, while the corresponding figure for girls was
0.1 hour per day. Boys were also more often members of sport clubs (61%) than girls
(45%) and more active in unorganised physical activity. 78% of the boys and 64% of
the girls reached the recommended 60 minutes of at least moderate physical activity
per day. Another finding was that being involved in organised sports and being physically active in unorganised forms was a good indicator of reaching the recommended
activity level.
Westerståhl et al (2005) chose six regions in Sweden. One upper secondary school
was randomly selected within each area. The aim was to investigate physical activity
levels and factors related to physical activity among 16-year-old boys and girls in upper secondary school practical and theoretical programs (n = 585). Data was collected by questionnaires, specially designed to measure frequency, intensity and duration of physical activity. Only 7% of the sample failed to respond to the questionnaire.
Energy expenditure was expressed as MET min day-1.More than 70% of the adolescents failed to achieve the recommended 60 minutes per day and more than 40% did
not reach the lower guideline of 30 minutes per day. Young people studying at practical programs were less physical active than those attending theoretical programs.
Especially inactive were girls in practical programs, where 85% failed to achieve the
goal of 60 minute moderate physical activity per day. Pupils in practical programs
also exhibit less positive attitudes to sports activities, reported fewer positive influences to perform physical activity, were from lower socio-economic background, had
lower perceived health and lower average school marks.
The data from this study suggest that promotion of physical activity should focus on
pupils, especially girls, in practical programs. Because the differences in physical activity levels between educational programs was partly an effect of less positive influence by parents, schools may provide an particularly important setting to increase
participation in upper secondary school pupils. Parental influences on their children’s`
vigorous physical activity and sport involvement have been known for long (see
Patriksson, 1995) and was also verified in a new Swedish study by Eriksson,
Nordqvist and Rasmussen (2008), who concluded that the family should be a key
target for interventions designed to increase physical activity for young people. The
children’s weight status was, however, not modifying the associations between parents' and children's physical activity in this study.
Participation in organised and informal sports (and tracking
tendencies)
Since the end of the 1960s a variety of investigations have tried to survey how many
young people who are members of a sport club. Sometimes, but not always, the crite18
ria has been an active membership, but the criteria for sampling have also been different and the studies are thus somewhat difficult to compare, even though they generally showed that the proportion of members has increased over time. This is especially true for girls. Many studies showed that more than half of all young people are
members of sport clubs. In certain ages, particularly in 10-13 years of age, about two
thirds or more participated in organised sport. In a recent study it was found that
about 90% of all Swedish children and adolescents have at some time been active in
a sport club (Wagnsson, 2009). The proportion of membership in sport clubs can,
however, vary strongly with residential areas , which means that background and environmental factors influence the disposition towards sport participation (Larsson,
2008; F Rasmussen et al., 2004).
Most of these studies, with Wagnsson (Wagnsson, 2009) as an exception, are crosssectional. There are, however, also some Swedish longitudinal studies that makes it
possible to see if there exist some tracking tendencies in physical activity in general,
physical fitness and sport participation. Of earlier studies, published before 2004, the
findings of (Barnekow-Bergkvist, Hedberg, Janlert, & Jansson, 1996a, 1996b) are
particularly important.
First, a short introduction of the underlying ideas of tracking. It is often assumed that
there is a high degree of integration between different phases through the life cycle;
the so-called continuity theory. Mainly through the socialisation process individuals
are thought to develop habits and preferences that become integrated into their lifestyle and as they grow older they are predisposed to maintain parts of their habits. In
accordance with such ideas it is also a common assumption that sport and physical
activity during childhood and adolescence has a critical influence of lifestyle later in
life. These rather simplistic ideas have, however, their limitations. Firstly, a rather deterministic view of human behaviour is assumed. Secondly, there is an enormous
spectrum of sports and physical activities which make it difficult to predict future behaviour, especially if there is a big difference of sports offerings in childhood (in
school PE and sport clubs) and in adult life. Thirdly, the continuity theory underestimates the importance of concurrent environmental factors that influence physical activity patterns.
In a short time perspective – following the same individuals 3-8 years – Swedish and
Finnish research (Telama, 2009) has given some support to the continuation theory.
There are rather high correlations between experiences of sport and physical activities in childhood and adolescence and physical activity as young adults.
When longitudinal studies cover a longer time perspective, the picture becomes more
complicated. Barnekow-Bergkvist et al (1996b) studied the same group (n = 425) at
two occasions (ages 16 and 34). At the second measurement the respondents were
also asked to answer retrospective questions about their physical activity when they
were 16-20, 21-25, 26-30 and 31-35. The correlations for self rated physical activity
two adjacent 5-year periods varied between .42 and .62 and were statistically significant. However, between the first and the last age period there was no significant relationship. More women (44%) than men (37%) changed their pattern of physical activity form inactive at the age of 16 to active at the age of 34. Around 40% of both sexes,
who had been inactive at the age of 16 were inactive when they were 34 of age. A
logistic regression analysis revealed that membership in a sport club significantly decreased the risk of inactivity at the age of 34 and also showed a complex relationship
between environmental factors and physical activity. Family situation (single-married,
19
children-no children) had a consistent influence on of physical activity patterns for
both men and women, but mostly for women.
The same team of authors (Barnekow-Bergkvist et al., 1996a) have also presented
data from the same subjects from a battery of physical fitness tests at the same ages
(16 and 34). The findings showed some tracking tendencies. They studied the proportion of men and women who remained in the lowest or highest quintile in the tests
of muscular endurance and strength. Among men there were 37% who stayed in the
highest quintile and 42% in the lowest, while the corresponding percentages for
women were 49% and 51%. It interesting to note that in a special follow-up made
twenty years later on a smaller group of women (36 women volunteered), the researchers (Barnekow-Bergkvist, Hedberg, Pettersson, & Lorentzon, 2006) could find
a statistical significant connection between being physical active and have a good
physical fitness at 16 year of age and bone mineral density (BMD) when they were
36 years old. These results support earlier findings that physical activity including
weight-bearing loading and strength exercises at young age are beneficial for bone
mass.
In a unique longitudinal Swedish study Engström (2008) has followed – from the beginning 1968 – more than 2000 15-year-old pupils every five years in almost 40
years. During later years Engström take his theoretical starting point in Pierre Bourdieu's conceptual framework, where sport habitus and cultural capital are key elements. The findings from the latest data analyses, when the respondents were 53
years of age, showed that neither membership of a sport club nor the amount of time
spent on sporting activities at the age of 15 had any significant associations with the
exercise habits displayed in middle age when the individual’s breadth of sport experience was used as a simultaneous control. Sport breadth was significantly connected
to later exercise habits. Also marks in physical education at age 15 had a significant
correlation with later physical activity patterns. An individual who was assigned the
highest sport habitus value at the age of 15 had a three times bigger chance of being
an exerciser in her/his middle age than a person with the lowest value. There is also
an almost five times greater chance that an individual with a very high cultural capital
as a 15-year old still will be an active exerciser 38 years later in comparison with individuals with a very low cultural capital. Another analysis showed that three current
environmental factors (place of residence, educational level and current friends'
physical activity habits) also had approximately the same correlations with physical
activity in middle aged persons.
Conclusions from the referred studies indicates that information of physical activity
from an early age is insufficient to get a good prognosis of physical activity levels of
middle aged persons, partly because the activities preferred often differ and that current circumstances – especially in adult life – also have an important influence on
lifestyle habits. These findings indirectly indicate that it is important to offer opportunities for young people to take part in different sports and recreational activities which
may be continued in adulthood.
Concerning aerobic fitness and cardiovascular status the following statement,
after reviewing research, was made about the situation around 2004: “A summary of
the reviewed studies in Sweden showed that aerobic fitness and cardiovascular status among children and youth are rather low. There is a tendency that MOU (maximum oxygen uptake, author’s comment) and other measures are somewhat decreasing and that an increasing number of young people have so low values that their cardiovascular health will be threatened if they do not change their lifestyle in a positive
20
way. This trend is especially clear among girls in practical programs in the upper
secondary schools” (Patriksson & Stråhlman, 2006, p. 5).
Only one peer-reviewed study was found after 2004 that could spread some light on
this complicated issue. This study (Hurtig Wennlöf, Yngve, & Sjöström, 2006) was,
however, very relevant and interesting. With the well-known background – already
discussed a lot in this report – of increased prevalence of overweight and obesity related to an unhealthy diet and insufficient physical activity the authors put the question “Whether this change in body size reflects lower physical activity levels among
young individuals, whether it is accompanied by a reduced aerobic fitness level, is
unclear. High aerobic fitness is considered to be among the most important healthrelated fitness components and is related to many biological health indicators…and
to lower all-cause mortality” (Hurtig Wennlöf et al., 2006, p. 79). Since reference data
on reliable physical activity is still insufficient for studying secular trends in a longer
time perspective, aerobic fitness data was chosen due to a longer scientific tradition
in that area. The aim of the study (the Swedish part of the European Youth Heart
Study, EYHS) was to present the levels of aerobic fitness in a random sample of
healthy schoolchildren (n =935) in central Sweden in grade 3 (age 9 to 10) and grade
9 (age 15 to 16) and to compare these data with corresponding data from early studies, especially from the Nordic Countries. The oldest Swedish study used as comparison was the classical one by Åstrand (1952), but also five other studies from 1961 to
1983 were included in the analyses. The difficult methodological issues that arise in
such comparisons over time were handled with great skills by the authors. The results showed that the aerobic fitness among 9- year old children had decreased
compared to earlier data, but in the 15- years old the result did not differ after adjustments for methodological differences. Further longitudinal studies are needed until
more accurate conclusions can be drawn in these manifold and complex issues.
Overweight and obesity
In a longer time perspective (two or three decades) there is no doubt that there has
been an increasing prevalence in Sweden of overweight and obesity among both
adults and young people. Also in Sweden researchers have called this trend the
“obesity epidemic” (A. Sjöberg et al., 2011) even if the prevalence is lower than in
most other countries and Sweden is still in the lowest tertile of obesity (M. Neovius,
Janson, & Rossner, 2006). Nationwide data for various age groups are scarce regarding overweight and obesity in children and adolescents. The most comprehensive reports stem from conscription records containing measured BMI on all 18-yearold boys each year (n = 50.000). These records showed that from 1971 to 1995 the
prevalence of overweight (BMI≥25 kg m-2) more than doubled from 6.9% to 16.3%
and obesity (BMI≥30 kg m-2) almost quadrupled to 3.2% in this group (F Rasmussen,
Johansson, & Hansen, 1999) . Later data from 1998, from the same registry, showed
a continued increase in overweight to 17.6% and obesity to 3.8% (F. Rasmussen &
Johansson, 2000).
Most of the available studies on younger age groups have been conducted on small
samples (n =‹1000). Strandell (2003) estimated, via a literature survey, that around
year 2000 about 4% of 10-year-old children were obese and 20-25% overweight. It
must, however, be stressed that Swedish studies of weight trends have been either
local as for example the study of Petersen et al (2003) or compared nationally not
representative samples over time as Ekblom et al (2004). In recent time some researchers have made efforts to collect national representative data. Werner and
21
Bodin (2007) sampled randomly all individuals that were born on the 15th of any
month in 1973 and 1981. Data for these two samples were collected from school
health records from all of Sweden, where trained nurses have taken all measurements. The data (height and weight) for both the 1973 cohort (n = 3579) and the
1981 cohort (n = 3107) were collected in three waves between 1989 and 2002 and
included all ages between 7 and 18. Comparing BMI-figures revealed a positive
secular trend at all ages. During the eight years covered by the study, the prevalence
of both overweight and obesity increased. Obesity grew more severe among both
boys and girls. It was also found that the average BMI of each age was reached one
year earlier in the 1981 cohort than in the 1973 cohort.
The latest studies in Sweden about overweight and obesity in young people are,
however, not national representative. Lissner et al (2010) have summarized data on
overweight and obesity rates among 10-11-years-old in different parts (including
Stockholm and Gothenburg) in Sweden, derived from available school records collected by various research groups in recent years. The findings indicated no significant increase in overweight or obesity in recently published studies of schoolchildren
in six municipalities. These studies offer a consistent picture of stabilizing obesity
rates, particularly in urban areas, but also with some evidence that the trend is reversing in girls and not in boys in the two biggest cities Stockholm and Gothenburg.
Ekblom, Bak and Ekblom (2009) followed a part of a sample randomly drawn from
the national register of schools in 2001. In the first study 508 (226 girls and 282 boys)
10-year olds were studied. In 2007 these children were contacted again at the age of
16. Of the baseline sample 53% of the girls and 63% of the boys accepted to take
part, a high drop-out rate, but no difference in baseline BMI was found between participants and non-participants. The results showed that the prevalence of overweight
plus obesity among 16-years olds was 17.9% in 2001 and 17.6% 2007.This finding
indicate that the earlier steady increase in body fatness may have eased off during
the studied period of time. It can, however, not be excluded that part of this result can
be influenced by the so called statistical regression effect: the tendency that extreme
values from a first measurement tend to come closer to the mean when measured a
second time. A stepwise logistic regression analysis displayed that neither 2001 values of gender, level of moderate or vigorous physical activity, nor geographic region
of the school explained the individual’s overweight/obesity in 2007. However, higher
physical fitness in 2001 lowered the risk as well as high BMI at that time.
The relations between physical activity, physical fitness (and other factors) are, as
already have been documented in this report, complex and the results are sometimes
contradictory. In a study of 557 Swedish children and 517 adolescents from the European Heart Study (Ortega et al., 2007) the purpose was to study the associations
of physical activity (measured by accelerometer) and other factors predisposing to
overweight, with overweight and central adiposity in children and adolescents. Young
people who had a low level (first tertile) of vigorous physical activity were more likely
to be overweight (including obesity) and to have a high risk waist circumference than
those with a high level (third tertile) of vigorous physical activity. Similarly, those subjects who had a low or middle of total physical activity tended to have more overweight than those who had high scores on physical activity. Only vigorous PA was
related to high total fatness. Birth weight (see also Monteiro & Victora, 2005; Stocks,
Renders, Bulk-Bunschoten, Hirasing, & Van Buuren, 2011)) and TV viewing were
also associated with higher odds of having a high-risk waist circumference, but these
associations were attenuated when PA-variables was included in the analyses. In
22
addition, vigorous physical activity predicted the risk of being overweight independent
of parental overweight, which also showed a strong connection to overweight and
high-risk waist circumference in children and adolescents. Even if the present study
was cross-sectional with its limitations it (and other studies) point in same direction:
especially vigorous physical activity seems to be a key factor to prevent overweight/obesity in young people. This conclusion has received further support in additional analyses of the same material (Ortega et al., 2010).
It has also been shown in a Finnish study of 4240 twin individuals (to control for genetic factors) followed up to about 25 years of age that there is a vicious circle between physical inactivity and obesity (Pietiläinen et al., 2008). The authors conclude
their findings with these words: “In summary, this study underscores the causal role
of low PA as a risk factor of obesity and especially abdominal obesity during the transition from adolescence to early adulthood. Further our results show that a physically
inactive lifestyle triggers weight gain and vice versa independent of genetics effect.
Thus, when it comes to the vicious circle of physical inactivity and obesity, genes
confer dispositions not destinies” (italics added, Pietiläinen et al., 2008, p. 413).
So far, focus has been on studies that have an ambition more to generalise the
trends in youth overweight/obesity in Sweden than to go deeper into certain subgroups. Many of the referred studies have as “side results” either divided their materials in categories like gender, age, socio-economic status and geographical area or
used such variables as controls in statistical analyses. The studies that will be discussed now have the purpose to investigate certain one or more subgroup(s).
From a systematic review of European studies on overweight/obesity in children from
migrant and native origin we have some knowledge of the problem (Labree et al,
2011). It appeared that in most European countries for which data were available,
especially non-European migrant children, were at higher risk for overweight and
obesity than their native counterparts. Knowledge is, however limited, why these
children are at even higher risks than native children. The authors mean that: “Not
only socioeconomic disadvantage, generational status and length of stay should be
taken into account, but also cultural factors, such as specific exercise and food habits, combined with parental factors”.
Is it the same situation in Sweden as in other European countries; gender, socioeconomic status, geographical location, ethnicity etc play a central role influencing overweight/obesity and physical activity? Sweden could perhaps be regarded as an egalitarian society from an international perspective. However, depending on dwelling
place and socioeconomic status (SES) of their parents, Swedish children experience
different conditions and prerequisites for health, which will continue into adulthood.
Overweight /obesity has been more prevalent in areas with a large proportion of inhabitants with low compared with high SES, and smaller towns, villages as well as in
the countryside (Sjöberg et al, 2011). A local study conducted in Stockholm illustrated
these tendencies. Rasmussen et al (2004) studied a random sample of more than
3000 pupils at grade 9 (mean age 15.2 years). He and his co-workers found that
obesity was strongly related to the educational level of the mothers. There were also
clear connections between Swedish and foreign/immigrant backgrounds and overweight/obesity. 14.6% of young people with foreign/immigrant background had overweight compared with 11.7% among adolescents of Swedish origin.
In a recent study (A Sjöberg et al., 2011) data from a nationally representative survey
of 7-9-year old schoolchildren was used. The aim was to investigate the importance
23
of social factors in prevalence of overweight and obesity. A special focus was the
impact of urbanization, level of education in the children’s living area and type of municipality on prevalence of overweight/obesity and waist circumferences. Concerning
overweight they observed higher prevalence in rural compared with urban that could
partly be explained by educational differences. In contrast, for obesity the urban-rural
gradient was observed in boys only and remained after adjustment for education.
This study support earlier reports of more local character the importance of identifying areas with low socioeconomic status, particularly vulnerable if situated in rural
environments.
As a lot of research has depicted (see above) low socioeconomic status and having
migrated from certain parts of the world have been pointed out as predictors for
overweight/obesity. Key mechanisms to change this situation include, primarily, alteration of the balance between physical activity and dietary intake levels. A study by
Magnusson, Hulthen and Kjellgren (2005) aimed to explore patterns of food intake,
physical activity and perceived relationships between lifestyle and health among children in a suburb with low socioeconomic status and a high prevalence of immigrants
and refugees. Children (n =112) in a local school, aged 11-12, took part in the study.
Nineteen nationalities were represented. The results deviated strongly from national
representative Swedish studies. Thirty-one percent of the children were obese or
overweight. Thirty-four percent spent more than 3 hours daily watching TV or using
computer, a behaviour, which clustered with excess intake of sweet drinks and habitually skipping breakfast together with physical inactivity has negative effects on
overweight/obesity and are likely to create other health problems.
Although there are signs that the overweight and obesity levels have reached a plateau or even decreased in certain categories in Sweden, the average trends may,
however, hide that in special subgroups within the population the problems with
overweight/obesity remain strong, especially if social inequality is accelerating. There
are also promising tendencies regarding physical activity. Several studies indicate
that physical activity in general, even if the polarization between active young people
and passive seem to be growing, is slightly going up.
The reasons for the changes in development of overweight/obesity are not known,
but during the last decade the paediatric obesity has been highlighted in commercial
media and scientific literature. It is also of interest to consider population-based
changes during the years of stabilized obesity rates in Swedish young people. National statistics of food consumption indicate some positive trends in food habits in
the population as a whole. The consumption of fresh vegetables and some fruits increased. Sweetened beverages and candies did not continue to go up (Lissner,
Sohlstrom, Sundblom, & Sjöberg, 2010). One could speculate that Sweden had/has
favourable condition for a change. Since about 2003 there has been enormous media attention to overweight, healthy food habits and physical activity, which may have
the effect of an increasing common awareness of the problem in Sweden. During this
period of time many local activities have begun in child health care, in pre-schools,
schools and sport clubs. Sweden has a long tradition of public health activities such
as official nutrition recommendations, food based dietary guidelines and campaigns
for physical activity. In the sport and physical activity area, the Swedish government
started 2003 to invest very large sums of money for promoting sport for children and
adolescents (the “Handshake”). The money was administrated and distributed by the
Swedish Sport Confederation to projects conducted in sport clubs with the aim of recruit more young people to the sports movement (S. Eriksson, Kristén, Patriksson, &
24
Stråhlman, 2008) . In 2006 the new government continued this investment in a new
national project – the “Sports lift” – where the money was doubled during the next
four year period. The purpose was to recruit more youngsters to the sports movement and to keep them there for a longer time. The primary focus of these huge projects has been (and is) to involve young people who are inactive and not members of
sport clubs. It is reasonable to think that these massive investments in children and
youth sports have had an impact on physical activity in young people.
Target groups for the interviews in the next phase of the
projects
In spite of the general trends and efforts described above there are still young subgroups in Sweden, where many are physically inactive, have a sedentary lifestyle
and are overweight or obese. The research review done in this report has given
strong evidence that there are more girls, especially in adolescence, who are physically less active than boys (M. Dencker et al., 2006; Engström, 2008; Larsson, 2008;
F Rasmussen et al., 2004; Wagnsson, 2009; M. Westerståhl et al., 2005), adolescence are less active than children irrespective of gender (Berggren, 2001; Engström, 2008; Hurtig Wennlöf et al., 2006; Raustorp & Ludvigsson, 2007; Raustorp et
al., 2007; Wagnsson, 2009; M. Westerståhl et al., 2005) and older girls in practical
educational programs have lower levels in physical activity and physical fitness
(Berggren, 2001; M. Westerståhl et al., 2005). There are also tendencies that young
children of both sexes coming from lower SES are less physically active (F Rasmussen et al., 2004; Wagnsson, 2009).
Concerning overweight/obesity, data show very clearly that boys, especially adolescent boys, have higher BMI than girls (Ö. Ekblom et al., 2004; O. B. Ekblom et al.,
2009; Lissner, Sohlstrom, Sundblom, & Sjöberg, 2010; Ortega et al., 2007; F
Rasmussen et al., 2004; A Sjöberg et al., 2011; Werner & Bodin, 2007). There is also
a clear association to SES, where those coming from low strata have higher values
on BMI and other measures of fatness (O. B. Ekblom et al., 2009; Magnusson et al.,
2005; F Rasmussen et al., 2004; A Sjöberg et al., 2011). Other subgroups that are
more heavily afflicted by overweight/obesity are immigrants and young people living
in rural areas (Magnusson et al., 2005; A Sjöberg et al., 2011). Children and adolescents who a low level of physical activity are at higher risk of being overweight/obese
(Ortega et al., 2010; Ortega et al., 2007; Pietiläinen et al., 2008; F Rasmussen et al.,
2004).
From this summary, it becomes evident that the target groups among young people
in Sweden to be approached in the next phase of this project should include overweight and obese individuals from low socioeconomic groups, inactive adolescents
from rural areas, immigrant children and adolescents with a background, primarily
from outside Europe.
25
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32
Idrottsvetenskapliga rapporter –
Institutionen för kost- och idrottsvetenskap
Göteborgs universitet
Adress:
Box 100
405 30 Göteborg
Redaktör: Owe Stråhlman
1. Stråhlman, O., (2004). Idrott – mål eller medel. Göteborgs universitet: Idrottshögskolan.
2. Patriksson, G., Eriksson, S., Augustsson, C. & Stråhlman, O. (2004). Utveckling och
förnyelse av idrottsverksamhet” - en utvärdering av projektverksamhet som fått medel ur
Allmänna arvsfonden. Göteborgs universitet: Idrottshögskolan.
3. Patriksson, G. & Stråhlman, O., (2004). Young peoples lifestyle and sedentariness - the
case of Sweden and Denmark. Göteborgs universitet: Idrottshögskolan.
4. Annerstedt, C. (2006). Framgångsrikt ledarskap inom elitidrott. Göteborgs universitet,
Idrottshögskolan.
5. Stråhlman, O (2006). Elite sport career process, career analysis of former Swedish elite
athletes. Göteborgs universitet: Idrottshögskolan.
6. Stråhlman, O., Patriksson, G. & Annerstedt, C. (2008). Arbete – livsstil – hälsa. Resultat
och analyser av AB Previas databas Arbetsliv och Hälsa. Göteborgs universitet,
Idrottshögskolan.
7. Stråhlman, O. & Patriksson, G. (2008). Att rätta mun efter matsäcken. Förutsättningar för
att bedriva projekt om kostnadseffektivitet. Utvärdering av Handslaget. Göteborgs
universitet, Idrottshögskolan.
8. Patriksson, G., Stråhlman, O., Eriksson, S. & Kristén, L. (2008). Handslaget – från idé till
utvärdering. Om projekt, ekonomi och verksamhet. Utvärdering av Handslaget. Göteborgs
universitet, Idrottshögskolan.
9. Annerstedt, C., Annerud, E. & Stråhlman, O. (2009). Hälsoform: en analys av ett
hälsofrämjande koncept. Institutionen för pedagogik och didaktik, Göteborgs universitet.
I samband med omorganisationen av verksamheten vid UFN år 2010 påbörjades ny
indexering:
2012:
1. Patriksson, G., Stråhlman, O. & Eriksson, S. (2012). Blev Idrottslyftet ett lyft? Analys och
utvärdering av Riksidrottsförbundet, Akademiska Idrottsförbundet, Flygsportförbundet och
Korpen – Svenska Motionsidrottsförbundet. Göteborgs universitet: Institutionen för Kostoch Idrottsvetenskap.
2. Patriksson, G., (2012). Swedish young peoples´ lifestyles with focus on physical (in)activity
and overweight/obesity - a review of the research literature. Göteborgs universitet:
Institutionen för Kost- och Idrottsvetenskap.
Reports in Sport Science
Department of Food, Nutrition and Sport Science
University of Gothenburg
Address:
Box 100
405 30 Göteborg
SWEDEN
ISSN 1404-062X