S T U D Y P R O T O C O L Open Access
Efficacy and cost-effectiveness of a
Transdiagnostic group-based exercise
intervention: study protocol for a pragmatic
multi-site randomized controlled trial
, Britta Seiffer
, Johanna-Marie Zeibig
, Jana Welkerling
, Leonie Louisa Bauer
Anna Katharina Frei
, Thomas Studnitz
, Stephanie Rosenstiel
, David Victor Fiedler
, Florian Helmhold
, Eva Herzog
, Keisuke Takano
, Tristan Nakagawa
, Saskia Kropp
, Sebastian Franke
, Stefan Peters
, Lena Zwanzleitner
, Leonie Sundmacher
, Ander Ramos-Murguialday
, Martin Hautzinger
and Thomas Ehring
Background: Mental disorders are prevalent and cause considerable burden of disease. Exercise has been shown
to be efficacious to treat major depressive disorders, insomnia, panic disorder with and without agoraphobia and
post traumatic stress disorder (PTSD).
Methods: This pragmatic, two arm, multi-site randomised controlled trial will evaluate the efficacy and cost-
effectiveness of the manualized, group-based six-months exercise intervention “ImPuls”, among physically inactive
patients with major depressive disorders, insomnia, panic disorder, agoraphobia and PTSD within a naturalistic
outpatient context in Germany. A minimum of 375 eligible outpatients from 10 different study sites will be block-
randomized to either ImPuls in addition to treatment as usual (TAU) or TAU only. ImPuls will be conducted by
trained exercise therapists and delivered in groups of six patients. The program will combine (a) moderate to
vigorous aerobic exercise carried out two-three times a week for at least 30 min with (b) behavior change
techniques for sustained exercise behavior change. All outcomes will be assessed pre-treatment, post-treatment (six
months after randomization) and at follow-up (12 months after randomization). Primary outcome will be self-
reported global symptom severity assessed with the Brief Symptom Inventory (BSI-18). Secondary outcomes will be
accelerometry-based moderate to vigorous physical activity, self-reported exercise, disorder-specific symptoms,
quality-adjusted life years (QALY) and healthcare costs. Intention-to-treat analyses will be conducted using mixed
models. Cost-effectiveness and cost-utility analysis will be conducted using incremental cost-effectiveness and cost-
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* Correspondence: email@example.com
Faculty of Economics and Social Sciences, Department of Education &
Health Research, Institute of Sports Science, University of Tuebingen,
Faculty of Science, Department of Clinical Psychology and Psychotherapy,
Psychological Institute, University of Tuebingen, Tuebingen, Germany
Full list of author information is available at the end of the article
Wolf et al. BMC Psychiatry (2021) 21:540
Discussion: Despite its promising therapeutic effects, exercise programs are currently not provided within the
outpatient mental health care system in Germany. This trial will inform service providers and policy makers about
the efficacy and cost-effectiveness of the group-based exercise intervention ImPuls within a naturalistic outpatient
health care setting. Group-based exercise interventions might provide an option to close the treatment gap within
outpatient mental health care settings.
Trial registration: The study was registered in the German Clinical Trials Register (ID: DRKS00024152, 05/02/2021).
Keywords: Exercise, Exercise therapy, Health economics, Outpatient care, Mental health, Mental disorders,
Depression, PTSD, Panic disorder, Insomnia
Epidemiological data from 2019 suggests that 15.6% of
the German population suffered from any mental dis-
order in 2019 (point prevalence) . Mental disorders
result in a considerable burden of disease, for example
accounting for 6.4% of overall disability-adjusted life
years (DALYS) assessed in the 2019 epidemiological sur-
vey . From 2008 to 2018, the proportion of mental
disorders among all causes of death increased from 2.2
to 6.1% . The most prevalent disorders in Germany
are anxiety disorders and trauma- and stress-related dis-
orders (point prevalence: 7.1%), major depressive disor-
ders (point prevalence: 4.3%), as well as insomnia (point
prevalence: 4%) [1,3]. Notably, these disorders often
occur comorbidly  and share common underlying
aetiological and even maintenance mechanisms, such as
high perceived stress [5–7], low self-efficacy [8,9], sleep
disturbances , elevated anxiety sensitivity [11–13], or
repetitive negative thinking [10,14].
Worldwide, 27.2% of the DALYS attributable to men-
tal disorders can be explained by major depressive disor-
ders and 16.3% by anxiety disorders . In 2015, health
care costs in Germany caused by mental disorders
amounted to 44.4 billion euros . Of this, 8.7 billion
euros can be attributed to major depressive disorders,
1.7 billion euros to phobic and other anxiety disorders,
and 1 billion euros to insomnia. Mental disorders ac-
count for 13.1% of total costs and represent the second
highest cost group after cardiovascular disorders (46.4
billion euros, 13.7% of total costs). Major depressive
(RR = 2.63) and anxiety disorders (RR = 1.41) have also
been shown to increase the risk of cardiovascular disease
. Besides direct costs (e.g., treatment costs), mental
disorders cause indirect costs on the German job mar-
ket. With 14.4 billion euros overall, mental disorders
caused the second-highest lost production costs of all
diagnosis groups in 2019 . They further caused 117.2
million days (16.5% of all days) of incapacity to work,
which is the longest absences per sick leave of all disor-
ders . Amongst mental disorders, major depressive
disorders accounted for the most days of incapacity to
work (33.9 million days), followed by trauma- and
stress-related disorders (21.6 million days). Anxiety dis-
orders accounted for 7.6 million days and insomnia for
0.5 million days.
Despite the severe negative impact of mental disorders,
it is estimated that in Germany only 10% of all affected
individuals receive evidence-based treatment and only
2.5% receive psychological treatment . In addition,
even those receiving psychological treatment often have
to wait before treatment initiation; for example, 40% of
outpatients waited three to nine months to start psycho-
therapeutic treatment in German health care settings
. Longer waiting times are associated with worsening
and chronicity of symptoms and the development of co-
morbid conditions . The high prevalence and severe
burden of mental disorders in combination with the
large gap between people in need for treatment and
those actually receiving it  illustrates the need to de-
velop alternative efficacious, effective and efficient
Exercise, defined as physical activity that is planned,
structured and repeated, with the primary aim to im-
prove or maintain physical fitness , has revealed
positive therapeutic effects for diverse mental disorders
. Most of the studied exercise interventions include
aerobic activities (i.e. running) or a combination of aer-
obic exercise with strengthening activities. Recent meta-
analyses on major depressive disorders and insomnia
have shown large effects for exercise that were compar-
able to those of psychological treatment and psycho-
pharmacological treatment [26,27]. A recent meta-
analysis on PTSD  found small to moderate effects;
however, in two of the four studies included, the inter-
vention comprised yoga. Looking at more recent evi-
dence from RCTs focusing on interventions including
aerobic exercise, large treatment effects were found [29,
30]. For panic disorder (with and without agoraphobia),
RCTs have revealed large effects on symptomatology
with both, acute exercise and structured multi-week aer-
obic exercise programs [31,32]. In addition, moderate to
large effects have been reported for exercise as an aug-
mentation to TAU for major depressive disorders, panic
disorder and PTSD [30,33,34]. Key components of
Wolf et al. BMC Psychiatry (2021) 21:540 Page 2 of 16
exercise interventions that have shown optimal thera-
peutic efficacy among patients with major depressive
disorders, insomnia, panic disorder with or without
agoraphobia and PTSD [35–38] include aerobic exercise
at moderate to vigorous intensity (MVAE) either or a
combination of MVAE with resistance training, con-
ducted two to three times per week, for 10 weeks with a
session duration of at least 30 min, supervised or par-
tially supervised by trained exercise therapists.
Exercise might not only be a promising efficacious
treatment but also carry the advantage of being highly
efficient, since it can be delivered in group settings
with relatively short durations , can be offered to
patients with heterogeneous and burdensome mental
disorders, can be expected to show a low likelihood
of adverse effects, comes at a relatively low cost, and
is suited to reduce the risk for cardiovascular diseases
that frequently occur comorbid with mental disorders
[39,40]. Furthermore, exercise can be performed and
continued independently without professional supervi-
sion or only remote supervision. However, individuals
suffering from mental disorders often have difficulties
to initiate and maintain a physically active lifestyle
, which may be related in part to deficiencies in
motivation and exercise-related self-regulatory skills
in this population . Reassuringly, there is evidence
showing that exercise adoption and maintenance are
mediated by motivational and volitional aspects, such
as intention strength, action planning and barrier
management . A recent meta-analysis shows that
especially self-efficacy in building intentions and ac-
tion planning is crucial for sustained exercise behav-
ior change . One possible way to promote such
motivational and volitional aspects are the application
of behavior change techniques (BCTs) [45,46].
Despite the promising evidence for MVAE as an inter-
vention for patients with mental disorders, exercise pro-
grams or professional exercise therapy are currently not
provided as regular health services within the outpatient
mental health care system in Germany. With the aim of
combining the current evidence on the efficacy of
MVAE and sustained exercise behavior change with spe-
cific demands of a real-world outpatient health care set-
ting, ImPuls was developed as a manualized group
exercise intervention [47,48] for physically inactive out-
patients suffering from major depressive disorders, in-
somnia, panic disorder with or without agoraphobia and
PTSD. ImPuls integrates recent findings about the opti-
mal modalities of exercise for therapeutic efficacy, such
as optimal frequency, intensity, time/duration and type
of exercise (FITT criteria) for the targeted disorders and
evidence regarding sustainable behavior change by inte-
grating behavior change techniques (BCTs). The compo-
nents of this intervention are further tailored towards
the specific needs of outpatients with mental disorders
in the current German mental health care setting. Spe-
cific features are 1) the inclusion of a broad range of
heterogenous diagnoses for which prior research has
demonstrated therapeutic efficacy, 2) intervention deliv-
ery in group format, and 3) short duration (i.e., only 4
weeks of supervised MVAE sessions carried out inhouse
in each study site). The aim of the current study is to in-
vestigate the efficacy and cost-effectiveness of imple-
menting ImPuls within the outpatient mental health
care setting in Baden-Württemberg, a representative
state in South-West Germany. The following hypotheses
will be tested:
1. Participants in the intervention condition, who have
received ImPuls in addition to TAU, will show lower
global symptom severity at post-treatment and follow-up
assessments compared to a control condition with TAU
2. Overall costs in the intervention condition will rep-
resent a significant saving for the public health system
compared to the control condition at post-treatment
and follow-up assessments.
3a. The intervention will lead to significantly higher
levels of MVAE at post-treatment and follow-up assess-
ments compared to the control condition.
3b. The effect of condition on the reduction of the pri-
mary outcome global symptom severity will be mediated
by an increase in MVAE.
4. Participants in the intervention condition will show
lower disorder-specific symptoms (major depressive dis-
order, insomnia, panic disorder with or without agora-
phobia and PTSD) compared to participants in the
control condition at post-treatment and follow-up
We will further assess, if participants in the interven-
tion condition show more instances of clinically signifi-
cant change compared to participants in the control
condition at post-treatment and follow-up assessments
(Additional analysis to Hypothesis 1 and 4).
The study will be led by researchers based at the Univer-
sity of Tuebingen in Germany, and will be conducted in
10 different study sites across Baden-Württemberg, a re-
gion in South-West Germany. The entire project will be
conducted between September 2020 and February 2024.
The study has been registered at the German Clinical
Trial Register (ID: DRKS00024152, 05/02/2021) and has
been approved by the local ethics committee for medical
research at the University of Tuebingen (ID: 888/
A pragmatic multi-site block-randomized controlled
trial with two treatment arms (ImPuls + TAU vs. TAU)
Wolf et al. BMC Psychiatry (2021) 21:540 Page 3 of 16
and three points of assessment (pre, post, follow-up) will
be conducted (see Fig. 1). All outcomes will be included
at all assessments. Study completion and reporting will
be carried out in accordance with the Consolidated
Standards of Reporting Trials (CONSORT), the Tem-
plate for Intervention Description and Replication
(TIDieR)  and the Consensus on Exercise Reporting
Template (CERT) .
Patients will be recruited mainly via inpatient psychiatric
departments, family practices, general practitioners and
psychiatric and psychotherapeutic outpatient units. The
project will be conducted in collaboration with two
health insurances, the AOK Baden-Württemberg (AOK)
and the Techniker Krankenkasse (TK), who will support
the recruitment with a targeted approach of general
practitioners, psychiatrists and psychotherapists. All hos-
pitals, clinics and practices will receive information ma-
terial, such as flyers and posters, to inform their patients
about the project. In addition, AOK and TK will publish
articles in media distributed for their members during
the course of the project. The TK further will inform eli-
gible patients directly via phone calls. Recruitment will
be additionally performed via social media posts (Insta-
gram and Facebook), newsletters of professional associa-
tions, email distribution lists of universities, local
influencers and regional newspapers and television.
Interested patients will first attend a preliminary tele-
phone screening of eligibility criteria and will receive
general information about the project (see also Fig. 2).
Patients will be screened for somatic contraindications
for exercise via the Physical Activity Readiness Ques-
tionnaire (PARQ)  and will be informed that they
have to provide a physician referral for ImPuls before
pre-assessment. In case of any suspicion of somatic con-
traindications, that might oppose participation (e.g.,
heart diseases or orthopedic problems), patients will be
asked to provide an additional medical consult from
their general practitioner or a medical specialist. Eligible
participants will be invited for a first inhouse meeting
taking place in a study site close to their residence.
Within the meeting, they will provide written informed
consent for study participation, receive information
about the study site and will be screened initially for
symptomatology related to the exclusion criteria to pre-
pare for the structural diagnostic interview. The tele-
phone screening and initial interview will be performed
by trained research assistants. Following this first
inhouse meeting, psychologists with a M.Sc. degree
undergoing a training in cognitive-behavior therapy,
who will be trained by an external expert for structured
clinical interviews, will conduct the structured clinical
interview for DSM-5 (SKID-5-CV)  to confirm
Once six patients at the same site will be found to be
eligible for participation, they will receive online ques-
tionnaires via the web-based data management system
REDCap [53,54] and a accelerometer-based Physical
Activity sensors (MOVE 4; movisens GmbH) which will
be worn for seven consecutive days (pre-assessment).
Online questionnaires and the assessment of physical ac-
tivity will be carried out within a period of 14 days. On
Day 15, the six patients will be randomized as a group to
either the intervention or control condition. In case of
an assignment into the intervention condition, study
sites will have to start the intervention within 14 days.
Before the start of the intervention, global symptom as
well as disorder-specific symptom severity will be
assessed again to check whether participants meet the
cut-off criteria for a mental disorder. In each study site,
60 patients are planned to be recruited and randomized,
resulting in 10 allocations per site. The intervention
group will complete the exercise intervention in addition
to TAU, while the control group will receive TAU
within the real-world outpatient mental health care
Fig. 1 Research design of the pragmatic randomized controlled trial (RCT). Indicated is the random assignment into the intervention and control
condition, assessment points and all categories of the outcomes. TAU = treatment as usual, Pre = First assessment prior to randomization, Post =
post-assessment 6 months after randomization, Follow-Up = follow-up assessment 12 months after randomization. 6 eligible patients will be
block-randomized to either the intervention or control condition
Wolf et al. BMC Psychiatry (2021) 21:540 Page 4 of 16
setting in Germany. The TAU condition is intended to
represent the typical treatment patients receive in the
German outpatient health care system. The procedure of
the pre-assessment phase will be repeated six months
(Post) and 12 months (Follow-up) after randomization.
After the completion of all assessments, patients of the
control group will receive 450€as reimbursement for
Inclusion criteria are age between 18 and 65 years, mem-
bership of the insurance companies AOK BW or TK,
fluency in German, no medical contraindications for
exercise, and diagnosed according to ICD-10 with at
least one of the following disorders: major depressive
disorders (F32.1, F32.2, F33.1, F33.2), insomnia (F51.0),
panic disorder (F41.0), agoraphobia (F40.0, F40.01) or
PTSD (F43.1). Exclusion criteria include: Performing ex-
ercise with at least moderate intensity, more than once a
week for at least 30 min each, continuously over a period
of six weeks within the last three months before study
diagnosis, medical contraindication established by the
general practitioner or a medical specialist, acute mental
and behavioral disorders due to psychotropic substances
(F10.0, F10.2-F10.9; F11.0, F11.2-F11.9; F12. 0, F12.2-
F12.9; F13.0, F13.2-F13.9; F14.0, F14.2-F14.9; F15.0,
Fig. 2 Patient Flow of the pragmatic randomized controlled trial in accordance with CONSORT
Wolf et al. BMC Psychiatry (2021) 21:540 Page 5 of 16
F15.2-F15.9; F16.0, F16.2-F16.9; F17.2-F17.9; F18.0,
F18.2-F18.9; F19.0, F19.2-F19.9), acute eating disorders
(F50); acute bipolar disorder (F31), acute schizophrenia
(ICD-10 F20), acute suicidality.
power analysis (G*Power, version 188.8.131.52) [55,56].
Power analysis was conservatively based on the low-
est symptom-related post-treatment effect of exercise
(vs. TAU/waiting list) on all included clinical disor-
ders, namely the effect size of d = −0.348 (g = −
0.347) for symptoms of post-traumatic stress dis-
order . A two-sided t-test, alpha level of 0.05, a
test power of 80%, an equal cell population, and a
dropout rate of 30% were assumed. This calculation
resulted in N= 375, which is conservative enough to
detect the lowest expected treatment effect at the
post-treatment phase. However, we regarded this
sample size as the minimum and targeted a total
sample of N= 600, in order to have enough statis-
fined and published in a separate study protocol
regarding the evaluation of the entire implementa-
tion process based on the Medical Research Council
The randomization sequence will be generated inde-
pendently of the study coordinator and the research
team responsible for data collection and management.
The sequence will be generated using a varying-size per-
muted block design, stratified by study site. This proced-
ure will ensure an appropriate balance in the number of
treatment and control conditions per study site.
Randomization codes will be generated digitally and
concealed on a secure system. The group-allocation se-
quence will be concealed from the research team re-
sponsible for data collection and management until the
No assessors need to be blinded since primary and sec-
ondary outcomes will not be based on clinician ratings.
Accelerometer-based data will by prepared and proc-
essed by trained student assistants according to prede-
fined rules and specifications. Data will be stored and
monitored by an external data manager. The sponsor,
the research team responsible for data collection and
management and any study personnel that stands in dir-
ect contact with patients will be blinded regarding the
randomization prior to allocation of patients to condi-
tions. In addition, the data analyst will be blinded re-
garding the treatment allocation. Specifically, he will
receive the final dataset, which will be masked for the
treatment condition (the “condition”variable only in-
forms Condition A or B but no real labels of the treat-
ment and control conditions). An unblinded data
manager will handle the raw data when exporting the
data from REDCap.
Global symptom severity Global symptom severity will
be assessed by the Global Severity Index (GSI) of the
German version of the Brief Symptom Inventory [BSI-
18] . The GSI reflects the general mental distress rat-
ing on the symptom scales somatization, depression, and
anxiety. Each symptom scale consists of 6 items. Thus,
18 items are rated on a 5-point Likert scale (range: 0–4).
Higher scores indicate higher distress. Cut-off scores
were evaluated separately for men (≥10) and women (≥
13) and have high sensitivity (91.2%) and specificity
(92.6%) . Among patients with affective disorders,
the GSI has demonstrated good internal consistency
(α= .89) and construct validity (r= 0.71). Among pa-
tients with anxiety disorders the BSI-18 has an internal
consistency of Cronbach’sα= .88 and a construct valid-
ity of r= 0.67 .
Major depressive disorder The secondary endpoint de-
pressive symptoms will be assessed with the PHQ-9 mod-
ule, assessing symptoms over the last two weeks with
nine items, each of them representing one of the DSM-5
(Diagnostic and Statistical Manual of Mental Disorders)
criteria for a depressive episode [61,62]. All items are
rated on a 4-point Likert scale (range: 0–3). The sum of
all items represents the total score (range: 0–27). Higher
scores indicate higher levels of depression. Regarding de-
pressive symptomology, individuals are classified accord-
ing to the degree of depression severity: absence of
depressive disorder (0–4), mild degree of severity (5–10),
medium major depression (10–14), severe major depres-
sion (15–19) and most severe major depression (20–27).
In medical settings the cut-off of ≥10 is used to detect a
major depressive disorder [61,63]. This cut-off was
shown to have a sensitivity and specificity of 88 and
85%, respectively . The scale measuring depressive
symptoms has an internal consistency of Cronbach’sα=
.87 among a representative German sample [61,65].
Insomnia / sleep quality Nonorganic insomnia will be
assessed with the German version of the Insomnia Se-
verity Index [ISI] [66,67]. The ISI consists of seven
items and assesses the severity of sleep onset difficulties,
Wolf et al. BMC Psychiatry (2021) 21:540 Page 6 of 16
sleep maintenance difficulties, early morning awakening,
satisfaction with current sleep, interference with daytime
functioning, noticeability of impairment attributed to
sleep problems and degree of distress or concern caused
by the sleep problem of the past two weeks. The total
score ranges from 0 to 28 (range of component scores:
0–3), with a higher score reflecting greater insomnia se-
verity. The cut-off score of ≥11 has shown a high sensi-
tivity (91.4%) and specificity (84.4%) in identifying
insomnia. The ISI has shown an internal consistency of
Cronbach’sα= .83 among a representative German sam-
Sleep Quality will be assessed with the global sleep
quality score of the German version of the Pittburgh
Sleep Quality Index [PSQI; 68]. The global sleep quality
score is the sum of seven sleep component scores (range
of component scores: 0–3): subjective sleep quality, sleep
latency, sleep duration, habitual sleep efficiency, sleep
disturbances, use of sleeping medications, and daytime
dysfunction. The global sleep quality score can vary from
0 to 21 with a cut-off score of 5, identifying clinically
raised sleep impairment . It has shown a high sensi-
tivity (98.7%) and specificity (84.4%) in identifying in-
Panic disorder and agoraphobia The seven-item Gen-
eralized Anxiety Disorder scale [GAD-7] [70,71] as-
sesses symptom severity of generalized anxiety during
the last 2 weeks, however shows good performance as a
screening measurement for panic disorder and agora-
phobia [72,73] and will therefor serve as a measure for
panic agoraphobia symptoms. Items are rated on a four-
point Likert scale (range: 0–3). The sum of all items rep-
resents the total score (range: 0–21), with scores of ≥5
representing mild, scores of ≥10 moderate and scores of
≥15 severe anxiety symptom levels, respectively. The
cut-off score of ≥10 has shown high sensitivity (89%)
and specificity (82%) . Among a representative Ger-
man sample, the GAD-7 has an internal consistency of
Cronbach’sα= .85 .
Besides the GAD-7, symptoms of panic disorder and
agoraphobia symptoms will be assessed with the three-
items subscale panic of the 6-items scale anxiety of the
BSI-18 . Current evidence suggests a four-factor
structure of the BSI-18 that retains the somatization and
depression symptom scales but splits the anxiety symp-
tom scale in two factors: General anxiety and panic [75,
76]. The subscale panic of the BSI-18 consists of three
items that are rated on a five-point Likert scale (range:
0–4). Among a German outpatient sample that was sur-
veyed five times after the 2nd, 6th, 10th, 18th and 26th
therapy session the best fitting model according to
Akaike Information Criterion (AIC) was always the
model with four factors, compared to one- and three-
dimensional models . Among patients with anxiety
disorders, the GSI of the symptom scale anxiety has
demonstrated good internal consistency (α= .83) and
construct validity (r= 0.67) .
Posttraumatic stress disorder To assess symptoms of
PTSD, the German version of the PTSD Checklist for
DSM-5 (PCL-5)  will be used. The questionnaire is a
self-report measure that consists of 20 items corre-
sponding to the DSM-5 criteria for PTSD. Participants
report their intensity of symptoms over the past four
weeks on a five-point Likert scale (0 = not at all to 4 =
extremely; total range 0–80). Higher scores indicate
higher levels of PTSD. The German Version shows high
internal consistency (α= .95), high test-retest reliability
(r= .91) and a high construct validity (r= .77). A cut-off
of 33 indicates clinically relevant symptomatology.
Health related quality of life Health related quality of
life will be assessed by the German version of the EQ-
5D-5L questionnaire [78,79]. It consists of five items
concerning the domains mobility, self-care, usual activ-
ities, pain or discomfort and anxiety or depression with
five answer alternatives each (range: 1–5). The combina-
tions of the answer alternatives can be described with a
five-digit number (i.e. the pattern 11,111 indicates the
optimal health state). Through the EQ-5D-5L question-
naire Quality Adjusted Life Years (QALY) are captured
for the economic evaluation. The EQ-5D-5L has an in-
ternal consistency of Cronbach’sα= .86 among German
chronic heart failure patients. Current data concerning
internal consistency in patients with mental disorders
exists for the Spanish version of the EQ-5D-5L. Among
Spanish patients with major depression the EQ-5D-5L
has an internal consistency of Cronbach’sα= .77 .
Routine data of the health insurances/health care
costs For the economic evaluation, patients’routine data
collected 6 months before the intervention, during the
time of the intervention, and six months after the inter-
vention will be provided by the two participating statu-
tory health insurers (AOK and TK). This data will
include patients’master data, such as gender and age, as
well as patient treatment costs. Parameters for treatment
costs will comprise costs of inpatient and outpatient care
as well as medication, medicals aids or days of incapacity
to work. Routine data for each patient will be provided
for the time of the intervention as well as one year prior
and one year after. The relevant costs are assessed and
aggregated as quantities. In addition, cost parameters
resulting from the intervention and the implementation
will be considered. Subsequently, routine insurance data
will be linked to primary data collected.
Wolf et al. BMC Psychiatry (2021) 21:540 Page 7 of 16
Exercise behavior/MVAE The assessment of self-
reported exercise duration and frequency and the assess-
ment of accelerometer -based moderate to vigorous
physical activity will serve as two proxies for MVAE. Ex-
ercise in minutes per week will be assessed using the
self-report Exercise Activity Index of the Physical Activ-
ity, Exercise, and Sport Questionnaire ([BSA question-
naire ;). Participants specify type, duration, and
frequency of exercise in the last four weeks. Moderate to
vigorous physical activity (MVPA) will be assessed via
accelerometer-based sensors (Move 4, movisens GmbH).
The sensor assesses physical activity of a person based
on kinematic data in three dimensions and atmospheric
air pressure. This allows to estimate the amount of phys-
ical activities of different intensities for a specified time
period based on validated algorithms . Patients will
wear the sensors for seven consecutive days. Volume of
moderate to vigorous physical activity will be indicated
in minutes/week and calculated by the daily physical ac-
tivity of at least moderate intensity (≥3 MET)/minutes.
Assessments to ensure internal validity
Symptom severity at randomizationSymptom severity
might change or fluctuate from the diagnostic interview
or pre-assessment to the start of the intervention. In
order to ensure clinically relevant transdiagnostic and
disorder-specific symptomatology with the start of the
intervention, scales that assess all primary and secondary
outcomes will be presented again between
randomization and group start: BSI-18 , ISI [66,67],
PSQI , PHQ-9 [61,62], GAD-7 [70,71], PCL-5 .
(Serious) Adverse EventsAdverse events (AE) will be
assessed at pre, post-1, and follow-up assessment. AEs
and Serious Adverse events (SAEs) can be further re-
ported by patients or therapists at a central phone num-
ber. AEs and SAEs will be documented and SAEs will be
reported to an independent Data Safety and Monitoring
Board, which will discuss adjustments to or discontinu-
ation of the entire study.
Treatment Fidelity (adherence to protocol of study
therapists)Core elements of the manualized ImPuls
intervention have been determined a priori. All inhouse
sessions (see Fig. 3and Table 1) of all therapists at all
study sites will be video-taped despite outdoor MVAE.
External research assistants will be trained to rate fidelity
based on deliverance as intended in the manual. A treat-
ment fidelity score will be determined as a mean of all
ratings. 10% of all video-taped sessions will be randomly
selected and analyzed. A fidelity score of ≥90% is
Dropout and attendance rates (patients) A drop-out
rate less than 30% and attendance rate ≥80% is assumed.
Attendance within the supervised (weeks 0–4; please
refer to Fig. 3) and partially supervised (weeks 5–24)
period will be assessed via the ImPuls smartphone appli-
cation and attendance lists by the exercise therapists/
study site. Participants who miss more than 4 consecu-
tive sessions during the four weeks of the supervised
Fig. 3 The temporal program structure and content overview of ImPuls. The dark gray boxes illustrate the supervised sessions with group
meetings (“Group Session”) and moderate to vigorous aerobic exercise (“MVAE”) as well as the supporters’session in week 5. The group sessions
integrate different behavioral change techniques (“BCT”) to enhance motivational and volitional skills with the long-term aim for maintenance
aerobic exercise. The medium gray boxes illustrate non-supervised aerobic exercise in which the patients can choose independently any aerobic
exercise that best fits to their interests and needs. The light gray box illustrates the non-supervised group sessions from week 5 to 24 in which
patients complete the aerobic exercise together but without the therapist. The telephones cartoons represent telephone contacts during the
non-supervised time to monitor the long-term maintenance of aerobic exercise. The entire program is supported by the ImPuls smartphone
application, developed especially for ImPuls
Wolf et al. BMC Psychiatry (2021) 21:540 Page 8 of 16
phase (of weeks 0–4) of the intervention (≥40%, due to
any reason) but continue the study assessments are de-
fined as treatment-dropout, since they did not receive
the intended dose of the intervention. They can still par-
ticipate in the remaining sessions of the intervention
and will be asked to complete all remaining assessments.
Participants who miss more than 4 consecutive sessions
during the four weeks of the supervised phase (of weeks
0–4) of the intervention (≥40%, due to any reason) and
discontinue the study assessments will be defined as
study dropout. Participants who will discontinue the
treatment as well as the assessments will be defined as
study dropout. All participants agree to be asked to spe-
cify their reasons for study/treatment-dropout on a vol-
untary basis (once, after treatment/study dropout). If
available, reasons for discontinuation will be reported. If
more than 50% of participants will discontinue their par-
ticipation in the intervention group during the first five
weeks (weeks 0–4) of the delivery, discontinuation of the
group due to lack of economic efficiency for the study
sites is possible. If only one participant of the interven-
tion group remains, he or she can no longer receive the
intervention, since delivery of the intervention to less
than two participants no longer qualifies as “group-based
MVAE dose within the supervised period (patients)
Frequency (at least twice a week), intensity (mean inten-
sity of least 64% of maximum heart rate) and duration
(at least 30 min of MVAE in each session) of exercise
during the supervised period (weeks 1–4) will be
assessed via the ImPuls smartphone application.
Expectations, motivation and satisfaction Validated
scales adapted for use in the context of ImPuls will be
employed to assess patients’outcome expectations ,
motivation  and satisfaction with the intervention
, as well as exercise therapists’motivation , and
satisfaction with the intervention . On all scales,
mean scores falling within the upper quartile will be
judged as indicative of high motivation for and accept-
ability of treatment, respectively, in patients and exercise
Process evaluation In addition to the goals related to
investigating efficacy and cost-effectiveness of ImPuls re-
ported in this study protocol, the overall project pursues
additional goals focusing on process evaluation and im-
plementation of ImPuls based on the Medical Research
Council Guidance  in the routine health care system,
which will be described in a separate study protocol.
Treatment as usual (TAU) The TAU condition will be
modelled to represent the typical treatment patients re-
ceive in the German outpatient health care system.
Therefore, patients will not be actively provided with
any treatment but patients are allowed to receive any
intervention that is available to them. Any evidence-
based treatment provided by the outpatient mental
health care system will be recorded, i.e., any psychiatric/
pharmacological or psychological/psychotherapeutic
intervention. Interventions, delivery or dosage of the
intervention can be changed and adapted during the
course of the study.
Table 1 Overview of behaviour change techniques included in ImPuls
Motivational (mainly weeks 1–2) Education about positive and negative effects of exercise
Education about optimal modalities of exercise to experience positive psychological effects
Selection of a preferred activity and level of intensity
Self-monitoring of exercise
Imagination of goals being reached in the future
Self-monitoring of goal achievement
Reflection about positive experiences/effects with/of exercise
Reflection about self-monitoring of exercise
Volitional (mainly weeks 3–4) Identification of barriers to exercise
Techniques to overcome barriers
Exercise planning through training plans
Motivational and volitional (weeks 4–24) Social support (family, friends) through the supporters meeting
Social support (other patients, self-organized group meetings)
Self-monitoring of goal achievement
Exercise self-monitoring trough diaries, training plans and analysis of FITT criteria (optimal modality)
All techniques/approaches will be delivered via the exercise therapists and protocoled, supported and guided by the ImPuls App
Wolf et al. BMC Psychiatry (2021) 21:540 Page 9 of 16
ImPuls The exercise intervention “ImPuls” will be
delivered to groups consisting of 6 patients and will be
divided into a supervised and partially-supervised period.
BCTs, such as goal setting, self-monitoring, formation of
concrete exercise plans and coping planning, will be in-
tegrated to promote sustained exercise behaviour change
[45,46,89]. The intervention structure and contents are
displayed in Fig. 3and Table 1. Please also refer to the
TIDieR-Checklist (Additional file 1_TIDieR-Check-
list.pdf as supplementary material). Participants will re-
ceive ImPuls in addition to TAU.
Supervised period (weeks 0–4) Patients will participate
in a combination of supervised MVAE sessions and
group sessions with educative elements integrating BCTs
(see Table 1) in groups with a total duration of 120 min
each session. Supervised MVAE will be provided twice a
week and will consist of either running or fast walking.
MVAE will last 30 min and participants can choose be-
tween a standardized interval-based or endurance
method protocol. Both training methods will be con-
ducted with at least moderate intensity, which is tracked
by a heart rate monitor (SIGMA iD.FREE) combined
with a chest strap (SIGMA R1 Bluetooth Duo Comfor-
tex+) and the Borg Rating of Perceived Exertion (RPE)
Scale . Moderate to vigorous intensity is defined as
at least 64% of maximum heart rate, subtracting age
from 220  and at least 13 points of the RPE Scale
. The ImPuls smartphone application (“ImPuls-
App”) developed specifically for ImPuls supports the
participants and therapists during MVAE. In weeks 2, 3
and 4 patients will engage in additional 30-min MVAE,
which is chosen based on their own interests and prefer-
ences. Therapists provide a list of MVAE highlights in
each study site (i.e. offers in local sport clubs, yoga stu-
dio, gyms) which can be found and selected in the
Partially supervised period (weeks 5–24 Participants
will be asked to engage in 30-min non-supervised
MVAE at least twice a week. Regular MVAE will be
planned through specific training schedules and accom-
panied by activity diaries, self-monitoring of goals and
volitional strategies and weekly (weeks 5–12)/biweekly
(weeks 13–24) phone calls with the exercise therapist,
intending to maintain motivation, volition, and adher-
ence to exercise. Training plans and all documentations
will be executed and coordinated via the “ImPuls-App”.
Information will be shared with the therapists in advance
prior to the phone calls. A session for patient’s sup-
porters (e.g., friends, partner) will be scheduled in Week
5 to inform them about the possibilities to support the
participants in transforming their intentions into action.
ImPuls smartphone application (“ImPuls-app”)The
ImPuls App will support the participants with options
for exercise planning (training plans), exercise guidance
(interval training, resistance program, ratings of per-
ceived exertion), self-monitoring of goal achievements
(analysis and feedback of FITT criteria and goal achieve-
ments), mitigation of barriers and a knowledge base. A
web-based application for exercise therapists will sup-
port planning and logging individual and group sessions
with clients (calendar, attendance, active participation,
notes). Furthermore, the participants can share some or
all of their data (such as their exercise schedule or their
plans for overcoming barriers) with their exercise thera-
pists via the secure channels between the ImPuls App
and the web-based platform. This will enable direct feed-
back of therapists to their clients. Both Apps run on
Google Android and on Apple iOS. All data generated
in the apps will be protected by encryption on the
smartphone. All communication between smartphones
(ImPuls App), browsers (Therapist’s App) and the cen-
tral server will be protected by established encryption
protocols, too. All components in Table 1will be docu-
mented in or provided by the ImPuls App.
Study therapists/exercise therapists To carry out the
intervention, exercise therapists will be required to have
one of the following academic or comparable basic qual-
ifications as physical activity and exercise professionals
with a training period of at least 3 years: academic de-
gree in exercise or movement science with at least 10
ECTS e.g.(i.e., 250 h) practice and 20 ECTS (i.e., 500 h)
theory (e.g. Magister, Bachelor, Master, Diploma Phys-
ical Education, Exercise Science, Exercise Physiology),
non-academic technical college degree Exercise and Car-
ing/Therapeutic Gymnastics with at least 21 semester
hours per week, non-academic technical college degree
„Physical Educator as liberal profession“, academic and
non-academic degrees in Physiotherapy. Moreover, a
specific additional therapeutic qualification DVGS e.V.
with 5 ECTS (i.e. 150 h) overall is required with the fol-
lowing content: Physical Activity-related Health Compe-
tence (2 ECTS, i.e. 100 h), Basics in Health Science and
Health Pedagogy (1 ECTS; i.e. 50 h), Basics in Psychiatry,
Psychosomatics and Addiction (1 ECTS, i.e. 50 h),
Affective Disorders (1 ECTS, i.e. 50 h).
All exercise therapists will be trained in ImPuls and
will receive a two-day and a one-day training at the Uni-
versity of Tuebingen. In case of missing a part of the
training, therapists will be offered an individual training
to catch up the missed elements. After the start of the
first intervention at each study site, exercise therapists
will receive a specific inhouse training within the first
two weeks to discuss and solve problems and questions
that arise with intervention start. After the inhouse
Wolf et al. BMC Psychiatry (2021) 21:540 Page 10 of 16
training, exercise therapists will be offered monthly
online-supervisions by two external and independent su-
pervisors, one with a background in cognitive-behavioral
therapy (CBT) and one with a background in exercise
therapy. Supervision can be attended on a voluntary
Study sites Study sites are local outpatient rehabilitative
and medical care facilities which were selected to cover
the different regions in Baden-Württemberg. They are
required to have premises for the group discussions (a
room for patient education, more than 12 square me-
ters) and the supporters’session (a suitable room for
10–20 persons; more than 30 square meters). An out-
door area for endurance-oriented exercise has to be
available and emergency equipment must be on-hand.
Every study site needs to have two to three employed ex-
ercise therapists with the described specific qualifica-
tions. Study sites enter into contracts with the German
Association for health-related fitness and exercise ther-
apy (DVGS e.V.) to ensure compliance to the above-
mentioned structural requirements and reimbursement
for conducting ImPuls.
To test Hypotheses 1, 2, 3a and 4 we will use multilevel
modeling to establish the treatment effects on the pri-
mary outcome (global symptom severity) and the sec-
ondary outcomes (major depressive disorders, insomnia,
panic disorder, agoraphobia, PTSD, QALYs, exercise). In
these analyses, each outcome will be predicted by the
group (ImPuls + TAU vs. TAU), time (pre vs. post vs.
follow-up), and their interaction. Given that the
randomization is stratified by study site, we will account
for the effects of study site in all analyses. All analyses
will be performed on intention-to-treatment basis, using
maximum likelihood estimations.
To test Hypothesis 3b, mediation analyses will be per-
formed to test the indirect effects of the treatment on
the primary outcome that are mediated by the changes
in the putative mediators (self-reported exercise in mi-
nutes per week, accelerometry-based moderate to vigor-
ous physical activity (MVPA); from pre to post, pre to
follow-up and post to follow-up). We will compute stan-
dardized change scores for the outcome and mediators
. In a path model (specified in the framework of
structural equation modeling), the group variable pre-
dicts the changes in the mediators, and these mediating
factors further predict the change score in the outcome.
The indirect effects are defined by the products of the
group-mediator and mediator-outcome effects. As ex-
ploratory analyses, we will also examine other forms of
mediations proposed by Goldsmith et al. , encom-
passing cross-lagged effects and latent change score
models. As recommended by Usami et al. , we will
first test whether these models fit the data well (and
which model fits the data best), and then investigate the
indirect effects of the treatment on the outcome.
To further analyze clinically significant changes (add-
itional analysis for Hypothesis 4 and 5), the Reliable
Change Index (RCI) [95–97] will be computed for each
individual between pre-, post and follow-up assessments.
Jacobson and Truax suggest combining the RCI with an
estimation of a cut-off point between a functional (non-
patient) and dysfunctional (patient) population, describ-
ing a clinically significant change [96,98]. We will check
if individual scores are more than 2 SD away from the
mean of the complete sample. Each individual will be
classified into one of four categories: recovered (individ-
ual has passed cut-off point of clinically significant
change and the RCI is greater than 1.96), improved (in-
dividual has not passed cut-off point but the RCI is
greater than 1.96), unchanged (individual has not passed
neither cut-off point nor is the RCI greater than 1.96),
or deteriorated (the individual’s RCI is greater than −
1.96). Non-parametric generalized mixed models will be
conducted to analyze differences between intervention
and control group.
Missing data will be handled by multiple imputations.
To test Hypothesis 2, the economic evaluation will de-
termine the cost-effectiveness and cost-utility of the
intervention condition comparing the intervention con-
dition with the control condition. Results are illustrated
as incremental cost-effectiveness and cost-utility ratios,
which illustrate the additional costs [Euro] incurred in
relation to the additional unit of effectiveness [transdiag-
nostic symptomatology] or utility [QALY]. Quality Ad-
justed Life Years (QALY) are captured by using the EQ-
The statistical uncertainty of the incremental cost-
effectiveness ratios will be evaluated by applying cost-
effectiveness acceptability curves (CEAC). During the
intervention period and follow up time, costs of out-
patient and inpatient care, outpatient medication and
days of incapacity to work are displayed as quantities. In
addition, cost parameters resulting from the intervention
and the implementation are considered.
The perspective of the statutory health insurances is
adopted and the results are examined with regard to a
transferability to the statutory health insurance popula-
tions. Sensitivity analyses, additional explorative sub-
group analyses and statistical uncertainty analyses will
provide a differentiated illustration of the results of the
economic evaluation. Differences in costs related to dis-
parities in age or comorbidities are additionally analyzed
using mixed models.
Wolf et al. BMC Psychiatry (2021) 21:540 Page 11 of 16
Exercise therapy is currently not provided within the
outpatient mental health care system in Germany, des-
pite the promising effects of exercise found for different
mental disorders , and despite its promise in bridg-
ing the severe gap of people in need and people actually
receiving evidence-based treatment. Especially for major
depressive disorders, insomnia, panic disorder with or
without agoraphobia and PTSD, there is evidence sug-
gesting that it is an efficacious treatment [26–34]. The
group-based exercise intervention ImPuls integrates re-
cent findings about optimal modalities of exercise for
therapeutic efficacy for the above-mentioned disorders
and sustainable behavior change by integrating behavior
change techniques (BCTs). The components of this
intervention are further tailored towards the specific
needs of outpatients with mental disorders in the
current German mental health care setting: 1) including
a broad range of heterogenous diagnoses for which prior
research has demonstrated therapeutic efficacy, 2) con-
ducting the intervention in a group format of 6 patients
supervised by 1 exercise therapist, 3) short duration (i.e.,
only 12 supervised inhouse sessions), 4) integration of a
smartphone application facilitating the transition to self-
dependent exercise, empowering the patient and the
A recent pilot study evaluating the efficacy of ImPuls
within a monocentric randomized controlled trial for pa-
tients with major depressive disorders, insomnia, anxiety
disorders, PTSD and ADHD showed therapeutic effects
comparable to disorder-specific exercise interventions or
established treatments, such as CBT . Besides the
promising efficacy, the intervention also showed a low
drop-out rate (18%) and a large and long-lasting increase
of exercise behavior in the intervention group. To the
best of our knowledge, this large pragmatic multi-site
trial will be the first in evaluating the efficacy and cost-
effectiveness of a group exercise program within a natur-
alistic outpatient mental health care setting among
patients with heterogeneous disorders. If results are
promising, exercise might be seen as an efficacious, ef-
fective, efficient and easily accessible treatment that
might be an option to improve the treatment gap within
the outpatient mental health care setting in Germany.
Specific challenges might arise during the current trial.
First, recruitment success might depend on regional cir-
cumstances. Some study sites are located in big cities
and some in smaller districts with smaller populations.
Thus, participation demands might be higher in some
study sites compared to others, which could lead to un-
balanced participation rates between sites or might have
further effects on the motivation of study therapists
since some might wait a long time to start their first
group while others might be pressured to start the
intervention. However standardized training and adapta-
tions in recruitment procedures might counteract these
challenges. The effects of study sites will be considered
in the statistical models. Second, recruitment and imple-
mentation started in March 2021 during the third wave
of the Covid-19 pandemic in Germany. Thus, patients
might be hesitant or anxious to participate in the study.
There might be a bias due to a potentially low participa-
tion rates of patients with anxiety disorders. This pos-
sible selection bias will be also modelled statistically.
In addition, another study protocol will be published
that goes beyond this study protocol and addresses in
more detail the relevant outcomes of the implementa-
tion process (implementation, context, mechanism of
impact), following the MRC framework .
AE: Adverse events; AOK: Allgemeine Ortskasse (German health insurance);
App: (smartphone) Application; BCT: Behavioral change techniques;
BSA: Physical Activity, Exercise, and Sport Questionnaire; BSA
questionnaire: Physical Activity, Exercise, and Sport Questionnaire; BSI-
18: Brief Symptom Inventory 18; CBT: Cognitive behavioral therapy;
CEAC: Cost-effectiveness acceptability curves; CERT: Consensus on Exercise
Reporting Template; CONSORT: Consolidated Standards of Reporting Trials;
DALY: Disability adjusted life years; DSM-5: Diagnostic and Statistical Manual
of Mental Disorders (5th version); DVGS: German Association for health-
related fitness and exercise therapy; ECTS: European Credit Transfer and
Accumulation System; EQ-5D-5L: Standardized measure of health-related
quality of life; FITT: Frequency, intensity, time, type; GAD-7: Generalized
Anxiety Disorder scale; ICD-10: International Classification of Diseases (version
10); ISI: Insomnia Severity Index; ITT: Intention-to-treat; MET: Metabolic
equivalent of task; MRC: Medical Research Council Guidance;
MVAE: Moderate to vigorous aerobic exercise; MVPA: Moderate to vigorous
physical activity; PARQ: Physical Activity Readiness Questionnaire;
PSQI: Pittsburgh Sleep Quality Index; PSQI: Pittburgh Sleep Quality Index;
PTSD: Posttraumatic stress disorder; QALY: Quality-adjusted life years;
RCI: Reliable change index; RCT: Randomized controlled trial;
REDCap: Research Electronic Data Capture (software); RPE: Rating of
Perceived Exertion; RPE Scale: Rating of Perceived Exertion Scale; SAE
: Serious adverse events; SKID-5-CV: Structured clinical interview for DSM 5 –
clinical version; TAU: Treatment as usual; TIDieR: Template for Intervention
Description and Replication; TK: Techniker Krankenkasse (German health
The online version contains supplementary material available at https://doi.
Additional file 1. TIDieR-Checklist.pdf (TIDieR Checklist).
The authors gratefully acknowledge all cooperating partners and exercise
therapists who carry out the intervention, cooperate in all matters of
research (e.g. documentation of sessions) and support the recruitment
process: RehaZentrum Hess (Bietigheim and Crailsheim), Therapiezentrum
Heidelberg (Theraktiv GbR), Ambulantes Zentrum für Rehabilitation und
Prävention am Entenfang GmbH, Karlsruhe; Universitätsklinikum Zentrum für
Physiotherapie, Tübingen; Vamed GmbH, Ulm; RehaZentrum Weingarten;
ZAR Göppingen; Rehamed Stuttgart; Rehaklinik / ZAPR Glotterbad, Freiburg.
We thank all general practitioners, psychiatrists, psychotherapists, clinics,
hospitals, social media influencers and newspapers that will support the
Wolf et al. BMC Psychiatry (2021) 21:540 Page 12 of 16
S.W., J-M.Z., B.S., N.E-K., L.Z., L.S., A.R-M., M.H., G.S., T.E. contributed to the
conception and the design of the study. Original draft preparation was
done by S.W. All authors contributed to the drafting and revision of the
final study protocol. S.W., J.-M.Z., B.S, J.W., L.B., T.S., A-K.F. are responsible
for study organization, recruitment and assessment, training of the exer-
cise therapists and data management. S.R., D. V.F. and G.S. are respon-
sible for the process evaluation, development of treatment fidelity score,
data management and trainings of the exercise therapists. F.H., A.R. and
A.R-M. are responsible for the app development and maintenance, S.P. is
responsible for the recruitment of the study sites and the qualification
of the exercise therapists, N.E.-K. and L.Z. are the representatives of the
2 health insurances, providing the routine data for the health economics
analysis and support patient recruitment, E.H., K.T., T.N. and T.E. are re-
sponsible for data management, data handling, the randomization pro-
cedure, analysis of treatment fidelity and statistical analysis, S.K., S.F., L.S.
are responsible for the health economics analysis. All authors have read
and agreed to the final version of this manuscript.
The German Innovation Fund of the Federal Joint Committee of Germany
fully funds the study from September 2020 to February 2024. The funding
association is neither involved in the study design, the collection, analysis
and interpretation of data, in the writing of the report nor in the decision to
submit an article for publication. Open Access funding enabled and
organized by Projekt DEAL.
Availability of data and materials
Individual participant data that underlie the results reported in this article
will be published after deidentification. Documents that will be shared
further: Study protocol, statistical analysis plan, analytic code, aggregated
individual study data. Routine/administrative data from health insurances will
not be made available. Access to data will be provided for anyone
legitimately interested in it. Analytic code and aggregated individual study
data will be made available on an online repository immediately after
publication (or within the peer review process). Participants give informed
consent to publish their data after deidentification (despite the routine/
administrative data from the health insurances).
Ethics approval and consent to participate
The study will be conducted according to the guidelines of the Declaration
of Helsinki of 2010, and was approved by local ethics committee for medical
research at the University of Tuebingen (ID: 888/2020B01, 02/11/2020).
Written informed consent will be obtained from all participants.
Consent for publication
The authors declare that they have no competing interests.
Faculty of Economics and Social Sciences, Department of Education &
Health Research, Institute of Sports Science, University of Tuebingen,
Faculty of Science, Department of Clinical Psychology
and Psychotherapy, Psychological Institute, University of Tuebingen,
Medical Faculty, Institute of Medical Psychology and
Behavioral Neurobiology, University of Tuebingen, Tuebingen, Germany.
Department of Psychology, Clinical Psychology and Psychotherapy, LMU
Munich, Munich, Germany.
Chair of Health Economics, Technical University
Munich (TUM), Munich, Germany.
German Association for health-related
Fitness and Exercise Therapy (German: DVGS), Hürth-Efferen, Germany.
Baden-Wuerttemberg, Stuttgart, Germany.
Received: 13 August 2021 Accepted: 22 September 2021
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