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Dittmer et al. Journal of Eating Disorders (2018) 6:27

https://doi.org/10.1186/s40337-018-0200-8

Specialized group intervention for compulsive exercise in inpatients with eating disorders: feasibility and preliminary outcomes Nina Dittmer1,2* , Ulrich Voderholzer1,3, Mareike von der Mühlen1, Michael Marwitz1, Markus Fumi1,

Claudia Mönch1, Katharina Alexandridis1, Ulrich Cuntz1,4, Corinna Jacobi2 and Sandra Schlegl5

Abstract

Background: Patients with eating disorders (ED) often suffer from compulsive exercise behavior, which is associated with lower short-term response to treatment and poorer long-term outcome. Evidence-based interventions specifically

targeting compulsive exercise behavior have been scarce so far. We developed a manualized group therapeutic

approach integrating cognitive-behavioral therapy, exercise therapy and exposure with response management to

promote healthy exercise behavior. Our objective was to examine the feasibility and acceptance of this new approach

as add-on to regular inpatient treatment in a pilot study. Additionally, we wanted to estimate preliminary effect sizes.

Methods: Thirty-two female, adolescent and adult eating disordered inpatients were recruited. According to the 4th ed. of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), twenty-six patients met criteria for Anorexia

nervosa (AN), two for Bulimia nervosa and four for eating disorder not otherwise specified. Semi-structured interviews

were conducted for qualitative evaluation of feasibility and acceptance of the new intervention. Patients completed

the Commitment to Exercise Scale (CES) and the Compulsive Exercise Test (CET) for assessment of compulsive exercise,

the Eating Disorder Inventory-2 for assessment of eating disorder pathology, the Beck Depression Inventory-II and Brief

Symptom Inventory for assessment of depressive and general psychopathology and the Emotion Regulation Skills

Questionnaire for assessment of emotion regulation before the beginning and at the end of the group intervention. Additionally, weight gain was monitored.

Results: Feasibility of our approach was confirmed. All patients reported a high satisfaction with both structure and content of the group. Between pre- and post-intervention, patients showed significant reductions in compulsive

exercise (effect size CES: 1.44; effect size CET total: 0.93), drive for thinness (effect size: 0.48), depressive symptoms (effect

size: 0.36), general psychopathology (effect size: 0.29) and acceptance of emotions (effect size: − 0.62). Patients with AN

also showed significant mean weight gain during the intervention (effect size: − 0.44).

Conclusions: Results of our pilot study indicate that our integrative approach to compulsive exercise in ED patients might represent a promising new therapeutic opti on. Feasibility and acceptance of the intervention were confirmed.

Preliminary effect sizes on most outcomes were promising. As improvements in Body-mass-index, eating disorder and

general psychopathology are also to be expected by routine inpatient treatment, a large randomized trial is currently

underway to evaluate the efficacy of this new intervention.

Keywords: Eating disorders, Compulsive exercise, Inpatient treatment, Specialized group intervention, Feasibility

* Correspondence: NDittmer@schoen-kliniken.de 1 Schoen Clinic Roseneck, Am Roseneck 6, Prien am Chiemsee, Germany

2 Department of Clinical Psychology and E-Mental-Health, Technische

Universität Dresden, Dresden, Germany Full list of author information is available at the end of the article

© The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. 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 stated.

Dittmer et al. Journal of Eating Disorders (2018) 6:27 Page 2 of 11

Plain English summary

Patients with eating disorders often suffer from compul-

sive exercise behavior, which is associated with lower

short-term treatment success and poorer long-term out-

come. Interventions specifically targeting compulsive ex-

ercise behavior are scarce. We developed a structured

group therapy to promote healthy exercise behavior by

reducing both the compulsive nature and excessive

amount of the patients’ exercise behavior. We evaluated

our new approach in inpatients with eating disorders in

a first small study: All patients reported a high satisfac-

tion with both structure and content of the group. Dur-

ing participation in the group therapy, patients showed

strong reductions in compulsive exercise behavior, eating

disorder and depressive symptoms. Underweight pa-

tients also showed a relevant weight gain. Due to these

promising results we are currently evaluating this new

therapeutic approach in a large clinical trial.

Background

Eating disorders (ED) are serious psychiatric disorders

often associated with a chronic course and significantly

elevated mortality rates [1–3]. A common and distinct-

ive symptom of Anorexia nervosa (AN) known for over

100 years is excessive physical activity despite severe

emaciation [4]. Compulsive exercise behavior is observed

in 31% to 81% of adolescent and adult patients with AN

depending on assessment method, sample and measure

used to assess compulsive exercise [4–7].

Several studies have shown compulsive exercise to be

associated with longer hospital stays and higher rates of

suicidal behavior. It also represents a significant pre-

dictor for relapse and chronic course of the eating dis-

order [8–11]. A review of the existing literature found

higher levels of dietary restraint [5, 12], anxiety [13–15]

and depression [12, 15] to be consistently associated

with compulsive exercise in AN. A high level of physical

activity, retrospectively assessed before the onset of the

ED during adolescence can also be regarded as potential

risk factor for AN [6, 16, 17]. Furthermore, obsessive-

compulsive symptoms and AN-subtype may be risk fac-

tors for compulsive exercise [12, 15, 18]. In the past

years, it has been suggested that hypoleptinemia may

represent an underlying endocrinological factor driving

hyperactivity in AN [19, 20].

Although examined less frequently compared with

AN, between 20% and 57% of patients with Bulimia ner-

vosa (BN) are reported to show compulsive exercise be-

havior [6, 15, 21]. For BN, “excessive exercise” at a

frequency of at least twice per week for three months

was explicitly listed as one of several inappropriate com -

pensatory behaviors in the 4th ed. of the Diagnostic and

Statistical Manual of Mental Disorders (DSM-IV) [22].

In the 5th ed. of the Diagnostic and Statistical Manual of

Mental Disorders (DSM-5) [23], the frequency of “exces-

sive exercise” as a compensatory behavior was reduced

to once per week for three months. In both DSM-IV and

DSM-5, only the quantitative dimension of this behavior

was taken into account.

Despite the importance of the phenomenon, there has

so far been no consensus concerning terminology and def-

inition of compulsive exercise: Several studies defined “ex-

cessive exercise” based on quantitative features such as

exercise frequency, intensity and duration [12, 14, 24, 25].

Other studies specifically emphasized the compulsive, rit-

ualized and uncontrollable quality of “compulsive exer-

cise” [26–28] or even regarded it as culturally rooted

variant of Obsessive-compulsive disorder (OCD) [25].

However, a recent Delphi Study by Noetel and colleagues

[29] found “compulsive exercise” to be the preferred term

for describing the phenomenon. Consensus was reached

among the international group of experts that a definition

of compulsive exercise should consider both quantitative

and qualitative dimensions [29]. Recent studies indicate

that compulsive exercise is maintained by a complex inter-

play of different factors - compulsivity, difficulties in emo-

tion regulation, weight and shape concerns and rigid and

perfectionistic personality traits [15, 18, 30, 31].

In our opinion, a comprehensive treatment rationale

targeting several of these factors is called for to address

the complexity of the behavior including the following:

1. Elements of Cognitive-behavioral therapy (CBT)

like psychoeducation and cognitive restructuring

are essential in challenging dysfunctional beliefs

about exercise, weight and shape [29, 32].

2. Exposure and response prevention strategies are

needed to target the compulsive quality of the

exercise behavior, as they are considered the first-

choice intervention for OCD [32]. Recent recom-

mendations for ED interventions put a special focus

on exposure treatment [33, 34], further validating

the integration of exposure in a treatment protocol

for compulsive exercise.

3. ED patients experience higher levels of emotion

intensity, have more difficulties in acceptance of

emotions and in emotion regulation and show

increased use of dysfunctional emotion regulation

strategies compared to healthy controls [35].

Compulsive exercise may serve as emotion

regulation strategy similar to food restriction or

bulimic behaviors [14, 24, 31, 36]. Training

affected patients in new and functional long-

term emotion regulation strategies seems

paramount.

4. Supporting the normalization of eating behavior by

supervised meals is considered a central element of

general ED treatment [34, 37, 38]. In analogy, a

Dittmer et al. Journal of Eating Disorders (2018) 6:27 Page 3 of 11

therapeutic approach for compulsive exercise

should include exercise-based elements directly sup-

porting normalization of exercise behavior.

In the 1980s and 1990s, first treatment approaches

applied response prevention techniques including one

hour of supervised bed rest after meals to reduce com-

pulsive exercise behavior [39]. A 2005 review by Hechler

and colleagues [40] showed that unstructured psycho-

education, self-monitoring of daily physical activ- ity and

cognitive restructuring were the most frequently used

treatment approaches.

Recently, two new treatment approaches were devel-

oped: Hay and colleagues [41] recently conducted a mul-

ticenter randomized controlled trial (RCT) in an

outpatient setting evaluating a new CBT-based treat-

ment approach. Schlegel and colleagues [42] developed

an exercise-based program for outpatients which is cur-

rently being evaluated in an RCT.

According to the rationale outlined above, we consider

it essential for a leap forward in the management of com-

pulsive exercise to address several of the maintaining fac-

tors like compulsivity, emotion regulation or distorted

cognitions as well as the establishment of a healthy exer-

cise behavior simultaneously. A therapeutic approach that

corresponds to this demand by comprising CBT-based

and exercise-based elements is still missing.

Our team aimed to fill this gap to further improve

treatment options for affected patients:

We developed an innovative therapeutic approach for

compulsive exercise behavior integrating CBT, exposure

and response prevention, emotion regulation techniques

and exercise-based elements in one manualized group

therapeutic approach. The current study aimed to exam-

ine feasibility and acceptance of this new specific approach

as add-on to regular inpatient treatment in a pilot study.

Additionally we aimed at obtaining pre-post data to esti-

mate preliminary effect sizes of the intervention.

Methods

Sample

Our sample consisted of N = 32 female adolescent and

adult ED inpatients admitted to a large hospital for be-

havioral medicine in Germany (Schoen Clinic Roseneck;

Prien am Chiemsee) between November 2012 and Janu-

ary 2013.

Inclusion criteria were: (1) DSM-IV diagnosis of AN

(307.1), BN (307.51) and atypical AN or BN/Eating dis-

order not otherwise specified (EDNOS) (307.50), (2)

presence of compulsive exercise, which was defined

based on modified DSM-IV criteria for OCD, thereby

taking into account qualitative and quantitative dimen-

sions (Table 1), (3) age: 14–45 years, (4) informed

Table 1 Working definition of compulsive exercise

Compulsive exercise

A. Compulsive exercise as defined by (1) and (2): 1) Repetitive exercise that the person feels driven to perform in response to an obsession or according to rules that must be applied rigidly 2) The exercise is aimed at preventing or reducing distress or at preventing some dreaded event or situation; however the compulsive exercise is clearly excessive

B. At some point during the course of the disorder the person has recognized that the compulsive exercising is excessive or unreasonable

C. The compulsive exercise causes marked distress, is time-consuming (takes more than one hour a day), significantly interferes with the person’s normal routine, occupational functioning, usual social activities or relationships or is continued despite medical injury or illness

Criteria A. + C. are considered obligatory, whereas criterion B. is optional

written consent and, in case of minors, additional in-

formed written consent by legal guardians.

Exclusion criteria were: (1) body-mass-index (BMI)

< 13 kg/m2 at the beginning of the intervention, (2)

drug, alcohol or other substance abuse, (3) presence

of additional severe psychiatric (i.e. psychotic and bi-

polar disorders) or neurological diseases (i.e. multiple

sclerosis) and suicidality, (4) concurrent treatment for

OCD, (5) severe somatic complications prohibiting

light to moderate supervised exercise, and (6) marked

cognitive impairment due to underweight severe

enough to preclude attending and following a

100 min group session. The clinical assessment of

cognitive impairment was based on the Association

for Methodology and Documentation in Psychiatry

(AMDP) System [43]: Patients had to report moderate

or severe deficits in comprehension, attention span

and short- or long-term memory or these deficits had

to be observable by the clinician during the screening

procedure.

The intervention

The intervention represents a combination of routine in-

patient treatment and a specific intervention for the pro-

motion of healthy exercise behavior as add-on intervention.

Routine treatment

The specialized inpatient treatment for patients with ED

consists of a multimodal cognitive-behavioral approach

and intense psychiatric and internist treatment. All pa-

tients receive individual treatment twice per week, a non-

specific problem-solving group treatment three times per

week and take part in a manualized, symptom-oriented

group intervention for ED patients. Furthermore, all ED

patients participate in supervised meals three times per

day, meal preparation classes, so- cial skills training and

art therapy. Patients can also take

Dittmer et al. Journal of Eating Disorders (2018) 6:27 Page 4 of 11

part in exercise therapy depending on their weight and

physical condition. All underweight patients are required

to gain at least 700 g per week, which is monitored by bi-

weekly weight checks and visualized on individual weight

charts. If no sufficient weight gain is reached, fur- ther

steps include an increase of food intake, administra- tion

of high caloric fluids or – in very severe cases – nasal

tube feeding.

“Healthy exercise behavior” intervention

In addition to routine treatment, all ED patients who

participated in the present study took part in a specific

manualized group intervention called “Healthy exercise

behavior (HEB)” which specifically targets compulsive

exercise behavior. The overarching goal of this inter-

vention is threefold: First, to reduce the excessive quan-

tity of the exercise behavior and reestablish “healthy”

exercise behavior, taking into account each patient’s

current weight and general health condition. Second, to

reduce the compulsive quality of the exercise behavior

and establish a more flexible exercise regimen. Third,

to re-experience joy, social interaction and relaxation

when exercising.

The HEB intervention is manual-based, comprises

eight sessions (of 100 min), takes place twice a week and

is delivered by a clinical psychologist and a sports ther-

apist. It is conceptualized as closed group for eight to

ten patients with sequential sessions. During each ses-

sion, cognitive-behavioral as well as exercise-based treat-

ment elements complement each other. Between the

sessions, patients are required to complete homework

tasks (e.g. behavioral analyses or interviews with peers).

Group sessions are supplemented by individual graded

exposure and response prevention tasks concerning

exercise behavior guided by one of the therapists. Table

2 summarizes the content of each group session.

Procedure

Patients were recruited consecutively during inpatient

treatment. Eligible participants answered a number of

screening questions covering inclusion and exclusion

criteria. Subsequently, they received detailed information

on the study and gave informed written consent to par-

ticipate. For minors, an additional briefing of their legal

guardians was provided via telephone. Informed consent

forms were sent out to the legal guardians and had to be

signed and returned. Outcome measures were compul-

sive exercise, BMI, ED psychopathology and general psy-

chopathology assessed within three days before the

beginning and after termination of HEB group.

Following the intervention, semi-structured interviews

were conducted by an independent clinician, where pa-

tients were given the opportunity for detailed feedback

concerning general set-up, therapeutic value and content

of the group therapy.

The study protocol was approved by the ethics com-

mittee of the University Hospital of Ludwig Maximilian

University Munich (project number: 060–13).

Measures

Measures for assessment of eligibility

Structured Interview for Anorexic and Bulimic Disorders

for DSM-IV and ICD-10 (SIAB-EX): The SIAB-EX is a

semi-standardized expert rating for the assessment of

ED symptoms and frequent additional symptoms. For

the current study, the diagnostically relevant questions

of the SIAB-EX [44] were employed.

Assessment of compulsive exercise: Compulsive exer-

cise was assessed by modified questions of The Struc-

tured Clinical Interview for DSM-IV Axis I Disorders

(SCID-I) [45, 46] for OCD (section F: anxiety disorders).

The questions of this clinical interview can be found in the

Appendix.

Feasibility and intervention acceptance

For assessment of feasibility and intervention accept-

ance, we assessed recruitment and retention rates, num-

ber of sessions attended, difficulties in integrating the

study into routine inpatient treatment and conducted semi-

structured interviews. In these interviews patients first

rated their satisfaction with the structure of HEB on a 5-

point Likert scale from 1 (= very satisfied) to 5 (= not at

all satisfied). They also rated whether they would

recommend the group to other affected patients (1 = full

recommendation to 5 = no recommendation). Following

that, they rated the overall helpfulness of HEB as well as

which therapeutic topics they considered to be most

helpful (1 = very helpful to 5 = not at all helpful). Pa-

tients were also asked what they especially liked about

the respective therapeutic element and whether they had

suggestions for improvement. Answers to these open

questions were recorded and transcribed.

Outcome measures for pre-post assessment

Commitment to Exercise Scale (CES) The CES [47,

48] is an eight-item self-report measure frequently used

for the assessment of compulsive exercise in patients

with ED. It reflects obligatory and pathological aspects

of exercise. Cronbach’s α for the overall scale was calcu-

lated as 0.82 [48], indicating a good internal consistency.

In accordance with Thome and colleagues [49], we used

a 4-point Likert scale instead of the original answering

format. Cronbach’s α in our sample was 0.88, implying a

good internal consistency. Convergent and divergent val-

idity of the measure were shown [48].

Dittmer et al. Journal of Eating Disorders (2018) 6:27 Page 5 of 11

Table 2 Content of “Healthy exercise behavior (HEB)” intervention

Symptom-oriented group intervention "Healthy exercise behavior (HEB)"

Session Content

CBT Exercise therapy Self-set goals for

1 Introduction: structure, content and goals of HEB Trying out different kinds of movement, playfula getting to know each other

the next session

Reflection of individual compulsive exercise behavior

2 Risk situations for compulsive exercise Life-kinetic exerciseb

Behavioral analysis of compulsive exercise Yoga

3 Group: exposure rationale and preparation Individually: actual exposures

Norms concerning "healthy exercise": differentiation between healthy and compulsive exercise behavior

4 Norms concerning "healthy exercise": differentiation between healthy and compulsive exercise behavior

Partner exercise "walking"

Playfula movement

5 "Myths and facts": psychoeducation Instructed exercise on body perception concerning different body structures

6 Alternatives for coping with high stress Trying out short, intense movement intervals for releasing high stress

Preparation: “One week with healthy leisure and exercise behavior”

7 Alternative emotion regulation: emotions as guides for needs

8 Review: “One week with healthy leisure and exercise behavior”

Conclusion

Expressing basic emotions

Trying out various kinds of exercise focusing on joyful, cooperative activities

CBT Cognitive-behavioral therapy; a Playful: Exploration of movement that focuses on fun and social interaction instead of competition and energy consumption; b Life-kinetics: Mental training that increases physical and cognitive performance by exercises that impose both physical and cognit ive demands

Compulsive Exercise Test (CET) The CET ([50];

Schlegl S, Dittmer N, Vierl L, Rauh E, Huber T, Voderhol-

zer U: Validation of the German version of the Compulsive

Exercise Test in patients with Eat Disord in preparation) is

a self-report inventory that assesses additional aspects of

compulsive exercise with five subscales: 1. Avoidance and

Rule-driven behavior, 2. Weight Control Exercise, 3. Mood

Improvement, 4. Lack of Exercise Enjoyment, and 5. Exer-

cise Rigidity. The inventory consists of 24 items that are an-

swered on a six-point Likert scale ranging from 0 (“never

true”) to 5 (“always true”). Cronbach’s α for the overall scale

was calculated as 0.85 [50], showing the good internal

consistency of the CET.

Cronbach’s α in our sample was 0.87, indicating a good

internal consistency. Concurrent and divergent validity

of the instrument were shown [50].

Eating Disorder Inventory-2 (EDI-2) The EDI-2 [51–

53] is a 91-item multidimensional self-report questionnaire

considered as gold standard for the assessment of core di-

mensions of disordered eating and related symptomatology.

It consists of 11 subscales and can be applied for adoles-

cents from age 13 onwards and adults. Cronbach’s α for the

overall scale was calculated as 0.96 [52], indicating an excel-

lent internal consistency. In our sample Cronbach’s α was

0.84, showing a good internal consistency. Convergent and

divergent validity of the measure were shown [52, 53]. Be-

yond the three main subscales Drive for Thinness, Bulimia

and Body Dissatisfaction of the EDI-2, we used the subscale

Perfectionism, as perfectionism is considered an important personality characteristic for maintaining compulsive

exercise behavior [31].

Beck Depression Inventory-II (BDI-II) The BDI-II [54,

55] is a self-report inventory that consists of 21 items and is

widely used as a screening instrument for the presence and

severity of depressive symptoms during the past two weeks.

It may be used for adolescents and adults from age 13 on-

wards. Cronbach’s α for the overall scale was between

0.89 ≤ α ≤ 0.93 in psychiatric samples [55], showing an ex-

cellent internal consistency. Cronbach’s α in our sample

was 0.90, indicating again an excellent internal consistency.

Convergent and divergent validity of the measure were

shown [55].

Brief Symptom Inventory (BSI) The BSI [56, 57] repre-

sents a 53-item self-report inventory that assesses subject-

ive impairment by nine physical and psychological

symptom groups. It can be used for adolescents and adults

from age 13 onwards. Cronbach’s α for the overall scale

Dittmer et al. Journal of Eating Disorders (2018) 6:27 Page 6 of 11

SDpre

was calculated as 0.92 for adults [56], showing an excellent

internal consistency. In our sample Cronbach’s α was 0.96,

indicating an excellent internal consistency. Validity of the

instrument was shown [56].

Emotion Regulation Skills Questionnaire (ERSQ) The

ERSQ [58] represents a 27-item self-report instrument

that assesses the situation-adapted interplay of different

emotion regulation abilities based on the Adaptive Cop-

ing with Emotions Model proposed by Berking [59]. It

may be used for adolescents and adults from age 12 on-

wards [60]. Cronbach’s α for the overall scale was calcu-

lated as 0.90, showing an excellent internal consistency

[58]. In our sample Cronbach’s α was 0.89, indicating

again an excellent internal consistency. Validity of the in-

strument was shown [58]. Based on the findings of Svaldi

and colleagues [35], we were especially interested in

changes concerning acceptance of emotions and emotion

regulation strategies, so we only used the subscales Ac-

ceptance of Emotions and Emotion Regulation of ERSQ.

Statistical procedures

Data were analyzed using Statistical Package of Social

Science (SPSS) software (Version 20.0) [61]. For all out-

comes, paired t-tests were used to assess pre-post

changes. Effect sizes (ES) were calculated using the for-

mula: ES ¼ Mpre −Mpost

as recommended for single group

pre-post study designs [62]. Here, Mpre represents the

sample mean of the respective variable before the

intervention, Mpost the mean of the same variable

after the intervention and SDpre the standard devi-

ation of Mpre. An alpha level of p≤ 0.05 was applied

to all statistical analyses.

Results

Participants

Of the 59 consecutively screened patients, 32 adolescent

and adult female ED patients (adolescents: n = 9; adults: n

= 23) were eligible: 26 patients met DSM-IV criteria for

AN, two for BN and four for EDNOS. Concerning non-

eligible patients, 17 patients did not meet inclusion cri- teria,

three patients denied participation and seven patients were

not eligible for other reasons. Clinical and demo- graphic

characteristics of the sample are presented in Table

3. Of the enrolled 32 patients, nine dropped out over the

course of the study, 23 patients completed the study.

Feasibility and intervention acceptance

Recruitment rate was 54.2%, drop-out rate was 28.1%.

However, only two patients (6.2%) specifically withdrew

from HEB study while continuing inpatient treatment,

the remaining seven patients dropped out of the entire

inpatient treatment. All patients who completed the

Table 3 Clinical and demographic characteristics of the sample

Subtype of eating disorder, n (%)

AN restrictive 19 (59.4%)

AN binge/purge 7 (21.9%)

BN non-purging 1 (3.1%)

BN purging 1 (3.1%)

Atypical AN and atypical BN/EDNOS 4 (12.5%)

Comorbid diagnoses, n (%)

OCD 2 (6.3%)

MDD 29 (90.6%)

Age, years

M (SD) 22.66 (8.25)

BMI at admission, kg/m2

M (SD) 15.41 (2.54)

Previous inpatient treatment, n

M (SD) 1.44 (1.89)

Length current treatment, weeks

M (SD) 15.69 (6.49)

Time from admission to participation in HEB, days

M (SD) 42.03 (31.28)

Time spent with compulsive exercise, hours/day

M (SD) 4.14 (2.74)

AN Anorexia nervosa, BN Bulimia nervosa, EDNOS Eating disorder not otherwise specified, HEB “Healthy exercise behavior” intervention, OCD Obsessive-compulsive disorder, MDD Major depressive Disorder, BMI Body- mass-index, M Mean, SD Standard deviation

study attended seven to eight HEB sessions. The only

difficulty in conducting the study in our inpatient setting

was to find time slots where overlap with other treat-

ment elements was minimized. Patients’ satisfaction with

the structure of HEB is summarized in Fig. 1.

Regarding recommendation of the intervention to

other affected patients, 85% of the patients stated that

they “fully recommend” participation in HEB, 15% stated

that they would “strongly recommend” participation.-

Concerning overall helpfulness of the intervention, 40%

of the patients indicated that they regarded HEB as “very

helpful”, 45% as “pretty helpful” and 15% as “partially

helpful”. One patient stated after her participation that

“I made a lot of progress. Of course, I am not completely

free of it, but that compulsion is much less. I have to go

for a walk, I have to go running - those urges are gone.” Figure 2 shows in detail, how the different therapeutic

topics covered in HEB were evaluated. Patients espe-

cially appreciated the differentiation between healthy and

compulsive exercise and the establishment of a healthy

norm concerning exercise, psychoeducation and graded

exposures. One patient described her astonish- ment “that

she [her healthy interview partner] does not exercise as

much as I thought a normal person would to

Dittmer et al. Journal of Eating Disorders (2018) 6:27 Page 7 of 11

stay slim.”, followed by the insight “And yeah, I really, extremely overdo it.”

Concerning graded exposures one patient pointedly de-

scribed “Yes, to really face my fears in this moment: fears of insane weight gain, fears of what is going to happen if I stop running. And to deal with the topics that arise if I do

not run away all the time, literally run away….”

Pre-post data

Pre-post changes in compulsive exercise behavior, weight

and BMI, ED symptomatology, depressive symptoms,

general psychopathology and emotion regulation as well

as estimated ES are summarized in Table 4. Patients

showed significant reductions in compulsive exercise be-

havior (effect size CES: 1.44; effect size CET total: 0.93),

Drive for Thinness (effect size: 0.48), depressive symp-

toms (effect size: 0.36), general psychopathology (effect

size: 0.29) and Acceptance of emotions (effect size: 0.62).

Patients with AN also showed significant mean weight

gain during the intervention (effect size: − 0.44).

Discussion

The aim of the present pilot study was to examine feasi-

bility and acceptance of a newly developed, add-on inter-

vention to inpatient treatment for compulsive exercise

behavior in patients with ED. Additionally we aimed at

obtaining preliminary pre-post data to estimate effect

sizes of the intervention in preparation for a larger RCT

to test the efficacy of the intervention. Our comprehensive

approach integrating cognitive-behavioral, exercise-based

and exposure and response prevention elements shows

promising results:

Implementation of the HEB study proved to be feas-

ible, recruitment and retention rates were comparable to

large studies [63], and patients reported good satisfac-

tion with both structure and therapeutic topics of the

HEB intervention in qualitative interviews. All patients

Fig. 2 Helpfulness of HEB topics

Fig. 1 Satisfaction with structure of HEB

Dittmer et al. Journal of Eating Disorders (2018) 6:27 Page 8 of 11

Table 4 Results of quantitative measures

Measure Pre-Intervention

Mean (SD)

Post-Intervention

Mean (SD)

t p Effect size

Commitment to Exercise Scale 3.23 (0.55) 2.45 (0.56) 8.00 < 0.001 1.44

Compulsive Exercise Test

Avoidance and Rule-driven Behavior 3.75 (1.06) 2.64 (0.98) 6.76 < 0.001 1.04

Weight Control Exercise 3.29 (1.24) 2.65 (1.07) 4.17 < 0.001 0.52

Mood Improvement 4.29 (0.78) 3.33 (1.09) 5.17 < 0.001 1.23

Lack of Exercise Enjoyment 1.71 (1.27) 1.92 (1.12) −1.25 n.s.

Exercise Rigidity 3.83 (1.06) 2.82 (1.03) 4.26 < 0.001 0.95

Total score 16.98 (3.88) 13.39 (3.43) 5.70 < 0.001 0.93

BMI (kg/m2) of AN patients 15.67 (1.54) 16.35 (1.50) −5.91 < 0.001 −0.44

Eating Disorder Inventory-2

Drive for Thinness 12.81 (6.52) 9.67 (6.36) 5.62 < 0.001 0.48

Bulimia 0.98 (1.71) 0.54 (1.44) 1.65 n.s.

Body Dissatisfaction 16.83 (7.16) 15.96 (7.18) 1.94 n.s.

Perfectionism 8.23 (4.44) 6.83 (3.07) 2.37 0.027 0.26

Beck Depression Inventory-II 1.36 (0.55) 1.16 (0.55) 3.42 0.002 0.36

Brief Symptom Inventory (General Severity Index) 1.37 (0.65) 1.18 (0.61) 2.42 0.024 0.29

Emotion Regulation Skills Questionnaire

Acceptance of Emotions 1.71 (0.89) 2.26 (0.79) −3.47 0.002 −0.62

Regulation of Emotions 1.40 (0.82) 1.49 (0.79) −0.68 n.s.

BMI Body-mass-index, M Mean, SD Standard deviation

stated that they would recommend participation in the

intervention to other affected patients, indicating a very

high acceptance of the treatment protocol.

Patients showed significant reductions on the CES

reflecting obligatory and pathological aspects of exercise.

We found significant reductions with mostly high effect

sizes on most CET subscales. Reductions were especially

marked on those subscales which best reflect the com-

pulsive nature of the exercise behavior (CET subscales

Avoidance and Rule-driven Behavior and Exercise Rigid-

ity). Additionally, we observed a significant reduction on

the subscale Mood Improvement, implying that compul- sive exercise was perceived as less enjoyable at the end

of the intervention. This might be explained by confron-

tation with the negative consequences of the compulsive

exercise during the HEB intervention. In addition to

changes in compulsive exercise behavior, AN patients in

our study achieved a significant weight gain. However,

weight gain is considered one of the major goals of in-

patient treatment, and in the absence of a control group

it is unclear which part of the comprehensive interven-

tion primarily drove the weight gain. Scores on patients’

EDI-2 subscales Drive for Thinness and Perfectionism were reduced. The significant reductions in these two

subscales are of particular importance, as eating path-

ology and perfectionism are considered key correlates of

compulsive exercise in the maintenance model of

compulsive exercise behavior proposed by Meyer and

colleagues [31]. Over the four weeks of participation in

the HEB intervention, patients’ ability to accept unpleas-

ant emotions when necessary increased. According to the Adaptive Coping with Emotions Model, the ability

to accept undesired emotions represents one of the

most relevant factors for mental health [59, 64],

which highlights the importance of improvement dur-

ing treatment. Since patients participated in a multi-

modal therapeutic approach in our hospital, their

improved emotion regulation strategies could be at-

tributed to their participation in the HEB intervention

directly or possibly to other elements of our

approach.

Discussing our results in the light of current research

on the topic, the scarcity of the same has to be kept in

mind. Schlegel et al. [42] conducted a pilot study to

evaluate their exercise-based program and reported high

reductions in CES total score together with a dropout

rate of 34%. A direct comparison of results seems diffi-

cult due to different therapeutic settings (inpatient vs.

outpatient) and samples (adults + adolescents with a

minimum BMI of 13 kg/m2 vs. adults only with a mini-

mum BMI of 17 kg/m2). At present, they conduct an

RCT for evaluation of the efficacy of their approach. To

our knowledge, results of the RCT of Hay and colleagues

[41] have not been published yet.

Dittmer et al. Journal of Eating Disorders (2018) 6:27 Page 9 of 11

Our concept of HEB seems very much in line with the

results of the Delphi study conducted by Noetel and col-

leagues [29]: Experts recommended to gradually reintro-

duce healthy exercise under supervision rather than to

completely prohibit exercise. Consensus was also reached

regarding the importance of psychoeducation on exercise

as well as patients learning emotion regulation strategies,

identifying risk situations and conducting behavioral ana-

lyses for compulsive exercise behavior - all core elements

of HEB. For future research, is seems crucial to develop

and validate a comprehensive clinical interview for asses-

sing compulsive exercise - which does not exist so far -

based on the items where consensus was achieved in the

Delphi Study. Due to its pilot character there are several

limitations to our study: First, the sample size of our pilot

study was small. Second, generalization of our results to

the general ED population might be limited by the follow-

ing two factors: Admission to inpatient treatment implies

a considerable severity of eating disorder symptomatology,

a BMI < 15 kg/m2, somatic complications or continuous

weight loss. In addition, ED patients choosing to partici-

pate in our study were possibly more motivated and less

anxious and rigid concerning the modification of their ex-

ercise behavior. Third, as no control group was imple-

mented in our study, our results, especially those

concerning BMI increase, have to be interpreted carefully,

as all AN patients, irrespective of their participation in our

study, were expected to gain at least 0.7 kg per week as

part of routine inpatient treatment. Comparable uncon-

trolled repeated measures study designs were however

used in inpatient ED studies by Gale and colleagues [65]

as well as Tchanturia and colleagues [66, 67]. Fourth, we

did not measure actual levels of exercise by accelerometry.

However, we consider measures of actual levels of exercise

(as assessed by accelerometry) and of cognitions and emo-

tions around exercise (as assessed by CES and CET)

equally important: We assume that changes in dysfunc-

tional exercise cognitions and the development of ad-

equate emotion regulation strategies (e.g. “non-exercise”

based emotion-regulation) provide the basis for changes

in actual levels of exercise. Additionally, levels of exercise

are usually restricted during inpatient treatment, so

changes in cognitions and emotions around exercise

might even better track “real changes” than changes in ex-

ercise levels. Of course, we integrated accelerometry in

our subsequent RCT.

Conclusions

Zipfel and colleagues [68] recognized treatment of com-

pulsive exercise as one of the key unmet challenges in

the treatment of ED. Our results indicate that our inte-

grative approach to compulsive exercise in ED patients

might represent a promising new therapeutic option.

This pilot study confirmed the feasibility and acceptance

of the intervention. Preliminary effect sizes on most out-

comes were promising.

However, to determine the efficacy of the HEB inter-

vention, a larger dismantling trial is needed, comparing

the multimodal routine inpatient treatment (treatment

as usual (TAU)) with the additional participation in HEB

as add-on module (TAU + HEB) and comprising a suffi-

ciently large sample size. Currently, our research group

conducts a large randomized trial to evaluate the efficacy

of this treatment approach as add-on element to regular

inpatient treatment number ( ISRCTN14208852). The

development of three new and different approaches in

the treatment of compulsive exercise in ED – one CBT-

based [41], one exercise-based [42], and one inte- grative

approach – offers fresh opportunities for this so far

neglected phenomenon [69]. Each is currently being

evaluated in large RCTs by the respective work groups.

Comprehensive, evidence-based therapeutic options for

compulsive exercise behavior becoming available will

represent a milestone for overall optimization of ED

treatment.

Appendix

Clinical interview for assessment of compulsive

exercise (preliminary version)

A1: Do you have to exercise over and over again and

can’t resist doing so? What do you have to do?

A2: Why do you have to exercise? What would happen

if you did not exercise?

B: Do you exercise more than you should or that makes

sense?

C1: What effect does your exercise behavior have on

your life?

C2: Does your exercise behavior bother you a lot?

C3: How much time do you spend exercising?

C4: Do you continue exercising when sick or injured?

Abbreviations AN: Anorexia nervosa; BDI-II: Beck Depression Inventory-II; BMI: Body-mass-

index; BN: Bulimia nervosa; BSI: Brief Symptom Inventory; CBT: Cognitive -

behavioral therapy; CES: Commitment to Exercise Scale; CET: Compulsive

Exercise Test; DSM-5: 5th ed. of the Diagnostic and Statistical Manual of

Mental Disorders; DSM-IV: 4th ed. of the Diagnostic and Statistical Manual of

Mental Disorders; ED: Eating disorders; EDI -2: Eating Disorder Inventory-2;

EDNOS: Eating disorder not otherwise specified; ES: Effect size;

ERSQ: Emotion Regulation Skills Questionnaire; HEB: “Healthy exercise behavior” intervention; M: Mean; MDD: Major depressive disorder;

OCD: Obsessive-compulsive disorder; RCT: Randomized controlled trial; SCID-

I: The Structured Clinical Interview for DSM-IV Axis I Disorders; SD: Standard

deviation; SIAB-EX: Structured Interview for Anorexic and Bulimic Disorders

for DSM-IV and ICD-10; SPSS: Statistical Package of Social Science;

TAU: Treatment as usual

Acknowledgements We sincerely thank all patients for their participation in our study. We

gratefully acknowledge the support of all colleagues at Schoen Clinic

Roseneck who contributed to this study. We especially thank Veronika Bauer,

Carolina Bürger, Christina Neumayr, Barbara Barton and Kerstin Hupe for their

assistance with data collection, data entry and data management.

Dittmer et al. Journal of Eating Disorders (2018) 6:27 Page 10 of 11

Availability of data and materials The datasets used and analyzed during the current study are available from

the corresponding author on reasonable request.

Authors’ contributions The HEB manual was developed by KA, UC, ND, MF, CM, MvM,and the

manual development headed by MM. HEB groups for the study were led by

KA, ND, MF, CM, MvM. Study design was developed by ND, UV, SS. ND was

responsible for patient recruitment and data collection. Data analysis was

completed by ND, CJ, SS. ND wrote the manuscript draft. UV, CJ, SS revised

the manuscript draft. All authors read and approved the final manuscript.

Ethics approval and consent to participate The study protocol was approved by the ethics committee of the Ludwig

Maximilian University Munich (project number: 060–13).Participants received

detailed information on the study and gave informed written consent to participate. For minors, an additional briefing of their legal guardians was

provided via telephone. Following that, informed consent forms were sent

out to the legal guardians and had to be signed and returned.

Competing interests The authors declare that they have no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in

published maps and institutional affiliations.

Author details 1 Schoen Clinic Roseneck, Am Roseneck 6, Prien am Chiemsee, Germany.

2 Department of Clinical Psychology and E-Mental-Health, Technische

Universität Dresden, Dresden, Germany. 3Department of Psychiatry and

Psychotherapy, University Hospital of Freiburg, Freiburg, Germany. 4 Paracelsus Medical University, Salzburg, Austria. 5Department of Psychiatry

and Psychotherapy, University Hospital of Munich (LMU), Munich, Germany.

Received: 21 January 2018 Accepted: 1 June 2018

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