STUDY PROTOCOLOpen Access
“läuft.” - a school-based multi-component program
to establish a physically active lifestyle in
adolescence: study protocol for a
cluster-randomized controlled trial
Vivien Suchert1*, Barbara Isensee1, Julia Hansen1, Maike Johannsen1, Claus Krieger2, Katrin Müller2, Ingeborg Sauer3,
Burkhard Weisser3, James D Sargent4and Reiner Hanewinkel1,5
Background: Physical activity during childhood and adolescence is associated with substantial health benefits and
tracks into adulthood. Nevertheless, only 22.7% of German adolescents are sufficiently physically active. Thus, the
promotion of an active lifestyle in youth is an essential issue of public health.
This study will evaluate the implementation and efficacy of the “läuft.” program to enhance physical activity in
adolescence. “läuft.” is a multicomponent school-based program developed on the basis of effective strategies for
health interventions and behavioral change.
Methods/design: The “läuft.” physical activity program targets four different levels. (a) Each student receives a
pedometer and documents his/her steps over 12 weeks using an interactive user account on the “läuft.” homepage.
(b) For classes there will be different competitions, with achieving the most steps in selected weeks, the highest
increases of steps and developing the most inventive ideas to promote physical activity in school. Besides, the
intervention includes four educational lessons. (c) The headmasters and teaching staff of the participating schools
will get information material with suggestions and encouragement to enhance physical activity in school.
Participating teachers will be invited to an introductory seminar. (d) Parents will be provided with informational
material about the program and will be invited to a parent-teacher conference about the benefits of being
physically active and how they can support their children in engaging in a physically active lifestyle.
To evaluate the efficacy of the “läuft.” physical activity program, a two-arm cluster randomized controlled trial will
be conducted in three waves: (1) baseline assessment, January/February 2014, (2) post assessment, June/July 2014
and (3) 12-month follow-up assessment, June/July 2015. Data collection will include physical and medical testing,
self-administered questionnaires, group discussions and document analyses.
Discussion: “läuft.” aims at fostering a physically active lifestyle in adolescence while a considerable decline of
physical activity is present. Physical activity programs based in the school setting and following a multicomponent
approach have been proven to be most successful. Furthermore, the use of pedometers is promising to enhance
physical activity during the entire day and targets a wide range of adolescents regarding fitness and weight.
Trial registration: Current Controlled Trials ISRCTN49482118.
Keywords: Physical activity, Cluster-randomized trial, Adolescents, School-based intervention, Pedometer
* Correspondence: email@example.com
1Institute for Therapy and Health Research, IFT-Nord, Harmsstrasse 2, Kiel
Full list of author information is available at the end of the article
© 2013 Suchert et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative
Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication
waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise
Suchert et al. Trials 2013, 14:416
There is extensive literature emphasizing physical activity
as an important and modifiable factor influencing physical
and mental health: being physically active on a regular
basis is associated with substantial health benefits [1-4],
including primary and secondary prevention of chronic
diseases, a reduced risk of premature death and better
Physical activity in childhood and adolescence prevents
a widespread variety of chronic diseases, including hyper-
tension, obesity and depression [5,6]. An active lifestyle
early in life is not just important for health outcomes in
adolescence but may also be a significant factor for the
level of activity in adulthood and health-related physical
fitness [7-10]. Global recommendations on physical
activity suggest that children and adolescents should
take part in physical activity of moderate to vigorous
intensity for at least 60 minutes per day to maintain
health . In consideration of epidemiological data,
only 17.3% of female and 28.2% of male adolescents in
Germany aged 11 to 17 years meet these recommen-
dations . Moreover, physical activity declines in
older adolescents compared to children and younger
adolescents . Nader et al. reported a decline of
moderate-to-vigorous physical activity from 180 minutes
per day at 9 years to only 42 minutes per day at 15 years
. Hence, the promotion of an active lifestyle and
physical fitness in early adolescence is an issue worthy
of intervention development.
Considering the access to a large adolescent population,
interventions based in the school setting are supposed
to be the method of choice for increasing physical
activity in youth . Meta-analyses and reviews indicated
positive impacts of school-based interventions for pro-
moting physical activity on health-related indicators,
namely an increase of rate and duration of in-school
physical activity as well as aerobic fitness and a decrease
of blood cholesterol and of physical inactivity [15-18].
Notably, multicomponent interventions involving peers,
parents and communities were assumed to be highly
effective . However, despite these encouraging out-
comes, almost no improvements in out-of-school physical
activity has emerged from studies to date, and increases in
activity level were rather short-term [17,18]. Therefore,
school-based programs which aim to enhance physical
activity and fitness in adolescents should also focus on
changing the everyday routine to increase out-of-school
physical activity and on establishing an active lifestyle
in the long term.
There are several options for interventions to induce
effects on physical activity throughout the entire day. One
promising approach could be the use of pedometers
which has already been shown to be effective in in-
creasing physical activity among adolescents [19,20],
not just in-school but also during out-of-school [21,22].
These findings are supplemented by studies emphasizing
self-monitoring and goal-setting as one of the most
effective intervention strategies to promote physical
activity [23,24]. Both strategies can be easily and effectively
combined with pedometer use . The “läuft.” program
integrates these strategies that have been proven to be
successful in the promotion of physical activity into a
multicomponent approach [15,18] that is school-based
[15,17,18] and includes social support from peers and
parents , goal-setting and self-monitoring through
pedometer use [23,24].
Objectives and hypotheses
The aim of the study is to evaluate the implementation
and effectiveness of the “läuft.” physical activity program
among adolescents in grade 8. Therefore, a two-arm three-
wave cluster randomized controlled trial will be conducted.
Expected effects on primary outcomes of the “läuft.”
program in the intervention compared to the control
group are defined as:
1. an increase in physical activity in general and in
different contexts measured by questionnaires;
2. a decrease of sedentary behavior measured by
3. an increase in cardiovascular fitness measured by
the 20-meter shuttle run test.
In addition to primary outcomes, the following second-
ary outcomes will be included in the evaluation study of
the “läuft.” physical activity program: body composition
(that is, Body Mass Index (BMI), percentage of body fat
mass and waist circumference), cardiovascular risk factors
(that is, blood pressure, heart rate after stress as well as
resting and recovery heart rate), mental health (that is,
general self-efficacy, psychological well-being, self-esteem
and depression), enjoyment of physical activity and sed-
entary behaviors, physical self-concept (that is, general
physical capacity and physical attractiveness), self-efficacy
towards physical activity, intention for physical activity
and physical well-being.
“läuft.” was designed by an interdisciplinary team of sport
medicine specialists, sport scientists, teachers, nutritional
scientists and psychologists.
The intervention operates at four levels: individual, class,
school and parents. The intervention period is 12 weeks.
An overview of all components of the intervention is
shown in Figure 1.
Suchert et al. Trials 2013, 14:416
Page 2 of 10
The core components of the intervention are class
competitions. On the one hand, each individual student
in the class receives a pedometer and records the daily
amount of steps over a period of 12 weeks. Steps are
summed up to a class mean, documented on a class
poster and reported to the project staff in three selected
weeks. On the other hand, each class collects creative
and inventive ideas on how to increase physical activity
in everyday school life and keeps records of these ideas
on the “läuft.” homepage (www.laeuft.info). In addition,
the classes take part in four educational lessons: (1)
introduction to the “läuft.” program, distribution of
pedometers and informational material for students
and their parents, (2) introduction to the creativity
contest, (3) physical activity that combines running/
walking with exercises at environmental facilities (for
example, a bench, stairs or a jungle gym), and (4) re-
flection of strategies to take more steps in everyday
life and setting of physical activity goals for the time
period after the project. Besides, additional modules are
offered that can be flexibly conducted during the program.
The modules deal with topics such as the reflection of
student’s physical activity, motives for being physically
active or possible barriers to physical activity and how
to handle them. Each lesson takes 45 minutes and will
be conducted by teachers of the participating classes.
After the end of the competition period, classes with
the highest means of steps per week, with the largest
increases and with the most inventive and creative class
projects are awarded.
By using a pedometer, each student can evaluate his or
her daily physical activity objectively and compare it
to the class mean and common recommendations.
Additionally, students can document their steps as well as
their experiences during the program using a private and
interactive user account on the “läuft.” homepage. Based
on students’ entries, statistics (for example, mean of the
week or day of best performance), a diagram to follow
daily step totals over time and feedback will be delivered.
Furthermore, the homepage provides opportunities to
share experiences with other participating students and
compete on step totals. The homepage is optimized for
online use with smartphones.
The headmaster and entire teaching staff of each partici-
pating school will receive information material, including
background and description of the program, activity-
promoting teaching methods, suggestions on how to
improve the school environment to stimulate physical
activity, and related links leading to further information.
All participating teachers will be offered an introductory
seminar to learn more about the concept and components
of the “läuft.” program.
A parent-teacher conference will take place at the class
level to emphasize the importance of physical activity
throughout the entire life and give parents ideas of how
to support their children in establishing a physically active
lifestyle. In addition, parents will receive information
material about the program and the assessments. To
take parents with a foreign background into account,
materials will also be available in Turkish and Russian as
the most frequently spoken foreign languages in Germany.
The effectiveness of the “läuft.” physical activity program
will be tested in a two-arm three-wave cluster randomized
controlled trial. Data of the different waves are hypothe-
sized to be clustered at the individual, class and school
level. Schools are the units of randomization and will
be randomly allocated to the intervention and control
group. In intervention schools the “läuft.” physical activity
program will be implemented, while schools of the control
group run through the usual curriculum and will receive
no further intervention. In both groups, fitness, medical
and questionnaire data will be collected for three times:
“baseline” (immediately before the intervention), “post”
(immediately after the intervention) and “follow-up”
(12 months after the end of the intervention) assessment.
In addition, after the intervention, qualitative analyses will
be conducted in classes of the intervention group to gain
insight into interactive processes within the classes and to
reconstruct subjective experiences and interpretations of
Process evaluation of the planned trial will be realized
through questionnaires and interviews during and after
the study, respectively. The study design is presented in
Figure 1 Overview of intervention components.
Suchert et al. Trials 2013, 14:416
Page 3 of 10
Sample size calculation
There are specific constraints for analysis of cluster
randomized trials  since the responses of individuals
within a cluster tend to be more similar than those of
individuals of different clusters. This clustering effect can
be defined as 1+(m-1)p, where m is the average number
of subjects per cluster and p the intraclass correlation
coefficient (ICC) . The ICC for physical fitness and
adiposity was taken from another cluster randomized
controlled trial, the Kindersportstudie (KISS) [28,29]
and estimated with approximately 0.05 (p). Assuming
an equal average cluster size of 20 pupils with parental
consent (m=20), a clustering effect of 1.95 was determined.
Without taking into account the clustering of the data,
assuming a small to medium effect size of the intervention
(Cohen’s d = 0.30) on physical activity as one primary
and the most important outcome being still detectable at
follow-up, applying a significance level of alpha = 0.05
and power=0.80, it can be estimated that N=350 pupils
are required to detect a difference between two inde-
pendent sample means [30,31]. Taking the cluster effect
into account, a required sample size of N=683 students
and 34 classes was determined. A computerized sample
size calculator for cluster randomized trials was used to
confirm this estimation .
Based on earlier experiences [33,34], a drop-out rate of
25% over the study was hypothesized. Hence, a total
sample size of 911 pupils and 46 classes will be recruited
for baseline to detect possible differences between the
groups at follow-up. In order to recruit the estimated
sample size of 46 classes while assuming a participation
rate of 20% and an average of at least two participating
classes per school, about 100 schools will be invited to
Procedure and participants
The study has been approved by the ethics committee of
the German Psychological Society as well as the Ministry
of Education and Science of Schleswig-Holstein. It targets
8thgrade classes with students aged 12 up to 15 years in
secondary schools in the federal state of Schleswig-
Holstein in Germany. Schools will be selected from a
complete list of all secondary schools in Schleswig-
Holstein obtained from the Ministry of Education. All
types of schools will be included, except schools for
disabled students. In order to recruit a study sample of
46 classes, about 100 schools will be invited to participate.
An invitation letter and information sheets about the aims,
methods and requirements of the study will be sent to the
head of each school. Copies of the letters of approval by
the Ministry of Education and the ethics committee will
be attached. Schools agreeing to participate must send
back their written consent indicating the acceptance of
study characteristics (including randomization), number
of grade 8 classes eligible for the study, names of the class
teachers, and number of students per class. All students of
participating classes will be included in the study. Schools
not agreeing to participate are requested to explain their
denial. In order to conduct non-responder analysis, all
invited schools will be asked to provide some basic data
about type and size of school, number of grade 8 classes,
gym and sports equipment, sports facilities on the school
ground and offered sports events, projects and courses.
Participating schools will be stratified (type of school and
number of grade 8 classes) and randomly allocated to the
intervention and the control groups. Furthermore, parents
will receive information sheets about the study and will be
asked for informed consent to the storage and use of
assessed data of their children. Teachers will register all
names of students with no permission in a list which they
keep throughout the entire trial. Students with refusals
will take part in the assessment but their data will not
To avoid interference between the intervention and the
control groups, stratified randomization will be carried
Figure 2 Study design.
Suchert et al. Trials 2013, 14:416
Page 4 of 10
out on the school level (according to the type of school
and number of grade 8 classes). Expecting a higher drop-
out of schools in the intervention group, randomization
follows a 3:2 ratio, that is, each school will have a 3:2
chance of being assigned to the an intervention group.
Randomization will be performed with a computer
From October 2013 to January 2014 the recruitment and
randomization of schools will take place. In the interven-
tion as well as in the control group, baseline data will be
obtained in January and February 2014. The intervention
program is scheduled for the period of March to May 2014.
During this time the control group runs the usual curricu-
lum. After 12 weeks, in the period of June to July 2014, post
assessment data will be obtained. The follow-up assessment
is planned for June and July 2015.
The program has been tested, evaluated and adapted
during a pilot study. From April to June 2013 a pilot
study with a shorter intervention period (eight weeks)
was conducted, including two schools with four classes
and 89 students (41 female students; Mage= 13 years,
SD =0.50 years). To evaluate and improve the “läuft.”
physical activity program, different qualitative and quan-
titative methods were employed: participant observation
of the educational lessons, questionnaires for students
and teachers to evaluate these lessons, and the assessment
as well as interviews with students and teachers about
the entire intervention. Based on the insights gained with
respect to feasibility, comprehensibility and acceptance
from the obtained data and experiences, the program was
modified. The intervention was followed by one assess-
ment in order to evaluate the feasibility of physical and
medical testing as well as the comprehensibility of the
questionnaire. The assessment was adapted in accordance
with the experiences and results.
The outcomes will be measured anonymously with self-
administered questionnaires, physical testing and medical
testing on the individual level as well as qualitative
methods on the individual and the class level. An overview
of all outcomes that will be assessed is presented in
To permit a linking of individual information on sub-
sequent assessments while assuring anonymity, each
assessment-booklet will be labeled with a seven-digit
individual code generated by the student .
Standing height will be determined using a portable
stadiometer (Seca 213, Basel, Switzerland) and body
weight as well as body composition (fat mass) using
Table 1 Overview of measures
Body weight and height (BMI percentiles)
Body composition (fat mass)
Waist circumference 
Resting heart rate
Heart rate after stress
Recovery heart rate
Cardiovascular fitness 
Socio-economic status 
Physical activity* [38-40]
Sedentary behavior 
Use of tobacco 
Use of alcohol [42,43]
Food pattern 
General self-efficacy 
Self-efficacy towards physical exercise 
Self-concept for general physical capacity
and physical attractiveness [47,48]
Enjoyment of physical activity 
Enjoyment of sedentary behavior 
Sensation seeking 
Physical well-being 
Psychological well-being 
Intention for physical activity 
Parental support for physical activity 
Friends physical activity*
Environmental situation to be physical active*
Activating-strategies (group discussion,
Interactive processes (group discussion)
Suchert et al. Trials 2013, 14:416
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bioelectrical impedance analysis (Omron BF-511, Omron
Healthcare, Mannheim, Germany). Students’ BMI will be
calculated and converted into age- and gender-specific
percentiles using the Coles LMS-method  on the
basis of a representative German sample . For further
analysis, the standard deviation scores will be determined.
Blood pressure and resting heart rate will be measured
with an automated oscillometric device (M5-Professional,
Omron Healthcare, Mannheim, Germany). A flexible tape
will be used to determine waist circumference at the
medial axillary line half-way between the lowest rib and
the iliac crest . For measuring heart rate after stress
as well as recovery heart rate after three minutes, re-
spectively, pulse watches with chest belts will be used
(Polar FT1, Polar Electro GmbH, Büttelborn, Germany).
The entire medical testing will be conducted under a
For measuring cardiovascular fitness, the 20-meter shuttle
run test will be conducted . In this progressive running
test, the students have to run between two lines for a
distance of 20 meters. The required running pace of an
initial 8.0 km/h increases continuously by 0.5 km/h
each minute. Students have to cross the opposite line
in a given time interval indicated by prerecorded audio
signals. The test stops when the student fails to reach
the line by the sound for the second time. To determine
aerobic capacity, the number of one-minute stages will
be counted with a precision of 0.5 stages. The 20-meter
shuttle run test allows a validated estimation of max-
imal oxygen uptake as an indicator of cardiovascular
Data about socio-demographic characteristics, lifestyle
behaviors well as psychological and social variables will
be collected by self-administered questionnaires. The items
and scales used are based on published and validated
questionnaires and the international literature. The entire
questionnaire was tested for feasibility and comprehensi-
bility during the pilot study with 89 students. Based on the
experiences in the pilot study regarding comprehensibility
and acceptance of items and conducted item analyses,
the questionnaire has been revised and shortened. Con-
sidering item analyses, items have been excluded if (a)
item difficulty was smaller than 20% and larger than
80%, respectively, (b) item-rest correlation was smaller
than .40 and (c) their exclusion either led to higher internal
consistencies or did not substantially decrease internal
consistency of the particular scale.
Table 2 summarizes item characteristics and internal
consistencies of the scales that have been modified
based on the results of the pilot study and that will be
employed in the planned study. Furthermore, for self-
constructed items and scales seven-day retest-reliabilities
were determined on a subsample of 38 students.
Socio-demographic characteristics Socio-demographic
characteristics like school type, age, gender and migra-
tion background will be assessed as well as the socio-
economic status asking for the parents’ highest educational
Lifestyle behavior Adapted items of the MoMo-activity-
questionnaire  will be used to assess physical activity
in different contexts (school, sports clubs and leisure time)
and in different dimensions (duration, frequency and
intensity) as well as the mode of commuting to school.
These questions provide information about physical
activity during a regular week. Besides, students in the
pilot study were asked with which activities they choose
to spend their recess time in school. The three activities
that were named the most (sitting or standing while talk-
ing to others, walking through the school or schoolyard,
and sports such as football or basketball) will be included
in the final questionnaire. Students will be asked how
often they engaged in these activities during the recess
times of the last week. Overall moderate to vigorous
physical activity will be determined by a reliable and
validated two-item screening measure . The survey
method for leisure time sedentary behavior was modified
from Zabinski and colleagues . Students will be asked
how much time they spent on the most recent school
day and the most recent Sunday with different sedentary
behaviors. Different physical activities were added to the
list providing insights into the distribution of sedentary
and active leisure time during a specific day. The list of
activities is based on the original questionnaire, categories
for physical activity (active transport, household activities,
physical activity in sports clubs, in school and in leisure
time), and extended by answers of students in the pilot
study. Lifetime smoking and current smoking  as
well as lifetime alcohol use, current alcohol use and fre-
quency/number of previous binge drinking [42,43] will
be assessed. Finally, students will be asked how often
they consume different foodstuff in a usual week, namely,
fresh fruits and vegetables, sweets or chocolate, soft
drinks, fast food and water  (retest-reliability (r)
ranged from 0.39 to 0.63).
Psychological variables Items of published and vali-
dated scales selected with respect to item analysis during
the pilot study will be used for the assessment of general
self-efficacy , self-efficacy towards physical activity
, physical self-concept for general physical capacity
and physical attractiveness [47,48], enjoyment of physical
activity PACES (Physical Activity Enjoyment Scale) ,
Suchert et al. Trials 2013, 14:416
Page 6 of 10
sensation seeking  as well as physical and psycho-
logical well-being . The enjoyment of screen-based
and non-screen-based sedentary behaviors will be assessed
with four adapted items of the PACES  (non-screen-
based sedentary behavior: r=.59). The scale “depressed
affect” of the German version of the Center for Epidemio-
logical Studies Depression Scale for Children CES-DC
[52,59] and three items to assess the intention for physical
activity were added to the questionnaire after the pilot
study. Thus, students will be asked how much they agree
with three given statements, (for example: “I plan to be
physically active for at least 60 minutes per day on most
days of the next week.”; seven-point semantic differential
scale from “likely” to “unlikely”) .
Social variables Parental support for physical activity
will be assessed by an adapted version of a scale used by
Trost et al.  (r= .80). Furthermore, students will be
asked how many of their friends are physically active
regularly (5-point scale: “none” to “all”, r=.72), how
many are in a sports’ club (5-point scale: “none” to “all”,
r=.69), how important it is in their circle of friends to
be physically active (4-point scale: “not important” to
“very important”, r=.50) and how often their parents
were physically active without them in the past week
(5-point scale: “never” to “more than five times”, r=.78).
Two items will be used to obtain information about the
environmental situation to be physically active: “In my
neighborhood there are many facilities in which for
being physically active.” (5-point scale: “strongly disagree”
to “strongly agree”, r=.60) and “When I want to do sports,
facilities and equipment are lacking.” (5-point scale:
“never” to “always”, r=.70). Finally, normative expecta-
tions of physical activity and screen time will be assessed.
Therefore, students will be asked for their estimation of
the portion of adolescents that are physically active for
60 minutes on a daily basis (r = .60) and how many
hours per day adolescents spend watching TV or on
the computer (r = .61).
In addition to and in combination with quantitative
methods, a qualitative analysis of processes and outcomes
of the “läuft.” program will be performed. During the
program, document analyses of students’ entries on the
homepage will be conducted. Group discussions with
students will be carried out in the course of the post-
Document analysis To gain insights into processes of
the intervention immediately, a qualitative document
analysis of activities on the “läuft.” homepage will be
conducted. The homepage can be used by students to
take part in the creativity contest, compete with their
amount of steps, share their individual experiences in
the program, discuss program associated topics and
participate in weekly tasks. Students’ activities and entries
on the homepage will provide information about the
activating-strategies that will be used and developed
during the intervention.
Group discussion (students’ perspective) In order to
obtain a deeper understanding of students’ experiences,
motives and interpretations of given impulses and acti-
vating-strategies during the program, group discussions
with selected members of each intervention class will be
conducted in the course of the post-assessment. On the
basis of a theoretical sampling , five to seven students
differing with regard to (a) gender, (b) interest in and
commitment to the “läuft.” program and (c) athleticism
Table 2 Item characteristics and internal consistencies of modified scales in their final version
Pilot study (N= 89)
Scales Number of ItemsCronbach’s α
Item-rest correlationItem difficulty (in%)
General self-efficacy5 .83.58 to .6660.8 to 68.2
Self-concept: general physical capacity5.92.78 to .8350.6 to 70.5
Self-concept: physical attractiveness5 .84.58 to .7157.9 to 76.1
Sensation seeking2 .8641.0, 43.6
Self-efficacy for physical activity8 .87 .56 to .7842.9 to 70.5
Physical activity enjoyment10 .92.58 to .8553.9 to 75.6
Sedentary behavior enjoyment (screen-based)*4
Sedentary behavior enjoyment (non-screen-based) 4.89 .57 to .8454.2 to 66.4
Parental support for physical activity2.7931.3, 34.8
Psychological well-being5.80 .46 to .7255.3 to 74.4
Physical well-being2 .7059.8, 66.1
*In the pilot questionnaire there were two separated scales for TV/DVD time and computer use. Both scales will be combined as overall screen-based sedentary
behavior. Hence, there are no item characteristics available for this combined scale.
Suchert et al. Trials 2013, 14:416
Page 7 of 10
will be asked to participate in the group discussions. These
will follow a thematic compendium and will be carried out
in accordance with the principles of Bohnsack , which
emphasize the self-deployment of the group and the
minor impact of the researcher on group processes.
To evaluate the quality of implementation, teachers will be
asked to fill in questionnaires about the realization of each
intervention component during the program. Information
about acceptance, feasibility and suggestions for improving
the program will be provided by another questionnaire
for all participating teachers after the intervention and
interviews with selected teachers. The latter will addition-
ally enable a more profound and case-oriented analysis of
interaction processes, barriers and success strategies. The
teachers will be selected using theoretical sampling based
on results of the questionnaires as well as formal criteria
(for example, gender and type of school).
Statistical analysis will be conducted with StataV13.1 (Stata
Corp, College Station, TX, USA) following the intention
to treat principle. To evaluate efficacy of the program,
multilevel analysis with the levels: schools, classes, individ-
uals and waves, will be performed. Random intercepts will
be included for schools, classes and individuals taking the
clustering effect into account. Group and covariates will
be taken as fixed effects. Differences between intervention
and control group at baseline as well as attrition analysis
will be examined using a t-test for independent samples
and Fisher’s exact test.
Qualitative data will be analyzed using ATLAS.ti software
(ATLAS.ti GmbH, Berlin, Germany). Following basic
methodological principles of the qualitative content ana-
lysis  and coding strategies of the grounded theory
approach , relevant categories will be generated,
systemized and summarized to permit thorough inter-
pretations of participants’ opinions and experiences.
The described study protocol is intended to evaluate the
efficacy of the “läuft.” physical activity program to enhance
physical activity of adolescents using a two-arm three-
wave cluster randomized controlled trial. “läuft.” is a
school-based program addressing an age group - ado-
lescents aged 13 to 15 years - in which the level of
physical activity declines dramatically [13,14]. Thus, to
accomplish an increase of the basic physical activity
level in everyday life the intervention is targeted on
four different components: individual, class, school and
In the promotion of physical activity in adolescence, a
multicomponent approach and interventions in the school
setting have been proven to be most promising and
successful strategies . Considering the easy access
to students from all levels of society and the long
period of time they spend in school, health programs in
the school setting can effectively reach a large number
of adolescents. On the other hand, many school-based
interventions were insufficient in enhancing not just in-
school but also out-of-school physical activity [17,18].
The “läuft.” physical activity program tries to overcome
this shortcoming by changing students’ everyday routine
by using pedometers throughout the entire day. Moreover,
pedometers have been proven to increase physical activity
also in low-active adolescents [21,22] who are at high
risk of adiposity, and poorer cardiovascular health and
fitness . The implementation of a follow-up assessment
12 months after the program ends, takes into account that
interventions for promoting physical activity in adolescents
are mostly limited to rather short-term effects .
Considering four educational lessons over a period of
12 weeks, time and effort for participating teachers are
rather low. Indeed, the intervention might not be intensive
enough to lead to major improvements in cardiovascular
risk factors, such as BMI or blood pressure, but the low
threshold for successful participation might also cause
better acceptance. Students do not need to be athletic
or of normal weight to achieve a high number of steps.
Nevertheless, universally applied programs also include
students that are already sufficiently physically active.
Thus, not all resources will be used efficiently. As the
main limitation of the presented study, physical activity
will be assessed by using self-administered questionnaires
and will not be measured objectively through accelerome-
ters. Even though, with respect to adolescents, reliability
and validity of self-administered recall-questionnaires
are acceptable to good ; aiming for triangulation of
quantitative and qualitative research methods, the qualita-
tive results pose an opportunity to reach a better and
deeper understanding of the barriers and prospects of
a “successful” intervention and aspired sustainability.
Suitable strategies and options can be deducted from
the quantitative-qualitative data and lead to concrete
recommendations for future implementation.
At the time of manuscript submission (September 2013),
the school recruitment was about to begin and will finally
be started in October 2013. First data assessment will start
BMI: Body mass index; CES-DC: Center for epidemiological studies depression
scale for children; ICC: Intraclass correlation coefficient; PACES: Physical
activity enjoyment scale; r: Retest-reliability.
Suchert et al. Trials 2013, 14:416
Page 8 of 10
The authors declare that they have no competing interests.
RH is the principal investigator. RH and BI supervise the study. RH, BI, JH, CK,
BW and JS took part in the study concept and design. RH, BI, JH, MJ, KM, VS,
IS and CK were responsible for the intervention concept. IS, MJ and BW were
responsible for determination of the medical assessment procedure. MJ and
IS were responsible for the determination of physical testing. VS, BI and RH
constructed the questionnaire. KM and CK determined the qualitative methods.
MJ, VS, KM, IS, BI and CK acquired the data during the pilot study. VS and BI
analyzed the statistical data of the pilot study. KM and CK analyzed the
qualitative data of the pilot study. VS, KM, MJ, IS, BI, CK and RH interpreted the
data of the pilot study. VS and JH drafted the manuscript. RH, BI, MJ, KM, CK, IS,
BW and JS performed the critical revision of the manuscript for important
intellectual content. All authors read and approved the final manuscript.
Acknowledgements and funding
IFT-Nord is responsible both for development and evaluation of the program
The “läuft.” physical activity trial is funded by German Cancer Aid in the
Priority Program Primary Prevention of Cancer (Nutrition and Physical
Activity, reference number: 110012). After a positive decision on applying for
study support, the German Cancer Aid does not influence the collection,
analysis or interpretation of data or the writing of the article and decision
to submit it.
We would like to thank our cooperation partners: Institut für
Qualitätsentwicklung an Schulen Schleswig-Holstein and Landesvereinigung
für Gesundheitsförderung in Schleswig-Holstein e. V.
Additionally, we would like to thank Annika Gröning, Sara Gotthard, Birte
Walther and Ansgar Deitert who supported us in data acquisition during the
pilot study, and the teachers and students that participated in the pilot study.
1Institute for Therapy and Health Research, IFT-Nord, Harmsstrasse 2, Kiel
24114, Germany.2University of Hamburg School of Education, Psychology
and Human Movement, Hamburg, Germany.3Christian-Albrechts-University
of Kiel, Institute for Sports Science, Kiel, Germany.4Geisel School of Medicine
at Dartmouth, Cancer Control Research Program, Norris Cotton Cancer
Center, Lebanon, NH, USA.5University Medical Center Schleswig-Holstein,
Institute for Medical Psychology and Medical Sociology, Kiel, Germany.
Received: 24 September 2013 Accepted: 20 November 2013
Published: 5 December 2013
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Cite this article as: Suchert et al.: “läuft.” - a school-based multi-component
program to establish a physically active lifestyle in adolescence: study
protocol for a cluster-randomized controlled trial. Trials 2013 14:416.
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