EMPIRICAL ARTICLE

Pathological Motivations for Exercise and EatingDisorder Specific Health-Related Quality of Life

Brian Cook, PhD1,2*Scott Engel, PhD1,2

Ross Crosby, PhD1,2

Heather Hausenblas, PhD3

Stephen Wonderlich, PhD1,2

James Mitchell, MD1,2

ABSTRACTObjective: To examine associationsamong pathological motivations for exer-cise with eating disorder (ED) specifichealth-related quality of life (HRQOL).

Method: Survey data assessing ED sever-ity (i.e., Eating Disorder Diagnostic Sur-vey), ED specific HRQOL (i.e., EatingDisorders Quality of Life Instrument), andpathological motivations for exercise (i.e.,Exercise Dependence Scale) were col-lected from female students (N 5 387) atseven universities throughout the UnitedStates. Regression analyses were con-ducted to examine the associationsamong exercise dependence, ED-specificHRQOL and ED severity, and the interac-tion of exercise dependence and EDseverity on HRQOL scores.

Results: The overall model examiningthe impact of ED severity and exercisedependence (independent variables) onHRQOL (dependent variable) was signifi-cant and explained 16.1% of the variance

in HRQOL scores. Additionally, the maineffects for ED severity and exercisedependence and the interaction amongED severity and exercise dependencewere significant, suggesting that the com-bined effects of ED severity and exercisedependence significantly impacts HRQOL.

Discussion: Our results suggest thatpathological motivations for exercise mayexacerbate ED’s detrimental impact onHRQOL. Our results offer one possibleinsight into why exercise may be associ-ated with deleterious effects on EDHRQOL. Future research is needed to elu-cidate the relationship among psychologi-cal aspects of exercise, ED, and HRQOL.VC 2013 Wiley Periodicals, Inc.

Keywords: exercise dependence;health-related quality of life; eatingdisorders

(Int J Eat Disord 2014; 47:268–272)

Introduction

Disease specific health-related quality of life(HRQOL) represents a disease or condition’s impacton the overall and specific areas of an individual’shealth and well-being, yet it is often overlooked asan outcome when examining the impact of psychi-atric disorders. Recent research on eating disorders(ED) and HRQOL has shown that both clinical andsubclinical ED individuals have lower levels ofHRQOL than normal controls.1 Furthermore, theHRQOL detriments observed in ED are on par withthe HRQOL detriments observed in other seriousdisorders (e.g., somatoform disorders, alcohol

abuse, diabetes, cancer, and pulmonary disor-ders).1 If the ED is left untreated HRQOL detri-ments may persist2; however, HRQOL improves asa result of ED treatment.3,4 Thus, identifyingbehaviors that may contribute to the detrimentalimpact on HRQOL may elucidate potential path-ways that, if intervened upon, could improveHRQOL.

Exercise is one behavior that is associated withearlier ED onset, more ED symptoms, and higherpersistence of ED behavior.5 Specifically, compul-sions are one pathological motivation for exercisethat has been associated with greater ED symp-tomatology (e.g., EDE global severity score, vomit-ing frequency, and depression).6 Consequently, thedistinction between exercise amount and patho-logical motivations is important in ED.7,8 Oneimportant limitation in synthesizing knowledgefrom studies that have examined pathologicalmotivations for exercise is the use of multipleterms to describe problematic patterns of exercise.While compulsive exercise is the preferred termused in the ED literature,9 a recent literature reviewhas concluded that terms such as exercise addic-tion, compulsion, and dependence all describe the

Accepted 6 September 2013

Supported in part by 5T32MH082761-05 from the National

Institute of Mental Health.

*Correspondence to: Dr. Brian Cook, Neuropsychiatric Research

Institute, Clinical Research, 120 8th St South, Fargo, North Dakota,

United States, 58103. E-mail: BrianCookPhD@gmail.com1 Neuropsychiatric Research Institute, Fargo, ND2 University of North Dakota School of Medicine and Health

Sciences, Fargo, ND3 Jacksonville University, Jacksonville, FL

Published online 17 October 2013 in Wiley Online Library

(wileyonlinelibrary.com). DOI: 10.1002/eat.22198VC 2013 Wiley Periodicals, Inc.

268 International Journal of Eating Disorders 47:3 268–272 2014

same phenomenon.10 Conceptualizing problematicexercise as exercise dependence addresses specificcompulsive attitudes, motives, beliefs, and behav-iors that are common to ED. Thus, recent researchhas shown that the detrimental effects of exerciseon ED may be mediated by exercise depend-ence.11,12 Moreover, exercise dependence is associ-ated with detriments in psychological well-beingand physical=cognitive well-being domains of ED-specific HRQOL.13

A recent review of HRQOL in ED concluded thatmotivations for exercising (e.g., exercise depend-ence) appear to predict HRQOL.1 Previous researchhas found significant relationships for exercisedependence and psychological aspects of HRQOLon ED symptoms,13 but has failed to investigate themain effects and interaction effect of ED severityand exercise dependence on total HRQOL scores.Therefore, continued examination of the associa-tion between exercise dependence and ED-specificHRQOL is warranted. The purpose of this studywas to examine the unique and interactive effectsof self-reported ED severity and exercise depend-ence on ED specific HRQOL. We hypothesized thatED severity will be more strongly associated withreduced HRQOL in individuals with higher levels ofexercise dependence.13

Method

Procedure

All study procedures were reviewed and approved by

the Institutional Review Board. Participants in this report

were from a larger sample13 examining the relationship

between exercise, health, and psychological states. Par-

ticipants were recruited from large lecture style classes

from seven colleges and universities in the United States

through announcements regarding a study. After com-

pleting the informed consent, the students were given a

pen and paper survey to complete during class time. The

survey took about 15 min to complete.

Participants

Participants were 387 female university students (M

age 5 20.11, SD 5 2.21). For educational level, most of

the women were sophomores (51.42%), followed by jun-

iors (21.19%), seniors (16.54%), freshmen (9.30%), and

graduate=professional (1.03%). The participants were

mostly Caucasian (65.89%) followed by African-

American (12.92%), Hispanic (8.53%), Asian (8.53%), and

others (4.13%). Full threshold (i.e., met all diagnostic cri-

teria) and subthreshold (i.e., at least one symptom was of

sub-diagnostic severity) ED severity assessed by the

Eating Disorder Diagnostic Scale14,15 revealed rates of

full threshold anorexia nervosa (1.30%), full threshold

bulimia nervosa (3.37%), subthreshold anorexia nervosa

(2.59%), and subthreshold bulimia nervosa (3.89%). Indi-

viduals with self-reported full and subthreshold anorexia

nervosa and bulimia nervosa were collapsed into one ED

group (n 5 43) and compared with individuals without a

self-reported eating disorder (n 5 324). Binge eating dis-

order was excluded from these analyses because physical

activity prevalence is low and may be uncorrelated with

measures of eating disorders and psychological function-

ing in individuals with binge eating disorder.16,17

Measures

Demographic Questionnaire. The Demographic Ques-

tionnaire assessed the participant’s self-reported year in

school, age, weight, height, and ethnicity.

Eating Disorder Diagnostic Scale (EDDS). The EDDS14,15

was used to determine ED symptoms and tentative diag-

nosis. The EDDS is a brief (i.e., 22 items) and psychomet-

rically sound measure for assessing symptoms and

diagnostic features of: (a) anorexia nervosa; (b) bulimia

nervosa; and (c) binge eating disorder. Cronbach’s a(alpha) was used to determine the scale’s internal consis-

tency and provide an estimate of reliability. The EDDS

reliability in this study was good (a 5 0.85). The EDDs

has shown high agreement with clinical interviews for

the assessment of anorexia nervosa (j 5 0.93) and buli-

mia nervosa (j 5 0.81).14

Exercise Dependence Scale (EDS). The EDS18 is a 21-

item measure assessing the physiological and psycholog-

ical aspects of exercise dependence symptoms. Examples

of items include: “I am unable to reduce how intense I

exercise”; “I exercise to avoid feeling tense”; and “I exer-

cise despite persistent physical problems”. Responses to

the items are on a 6-point Likert scale ranging from 1

(never) to 6 (always). A lower score reveals less exercise

dependence symptoms. Multiple validation studies and a

recent literature review have concluded that the psycho-

metric properties of this scale are good.10,18,19 The EDS

reliability in this study was excellent (a 5 0.97).

The Eating Disorders Quality of Life Instrument (EDQOL).

The EDQOL20 includes the following subscales: psycho-

logical, physical=cognitive, financial, work=school, and a

total score. The EDQOL is 25 item scale and it is more

sensitive to ED-specific aspects of HRQOL than generic

measures of HRQOL. Subscale and total scores may

range from 0 to 4, with a lower score indicating better

QOL. The EDQOL reliability in this study was excellent (a5 0.94).

Leisure-Time Exercise Questionnaire (LTEQ). The LTEQ

is a self-report of the frequency and duration that an

individual engages in strenuous, moderate, and mild

bouts of exercise during a typical week.21 Each of the

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International Journal of Eating Disorders 47:3 268–272 2014 269

intensity scores are converted into metabolic equivalents

(METS; [Mild x 3] 1 [Moderate x 5] 1 [Strenuous x 9])

and summed to provide an estimate of total METS

expenditure from exercise for an average week. The

LTEQ is a valid and psychometrically sound measure

that is frequently used to assess exercise behavior. The

MET values for the LTEQ are based on published reports

of its validity,21,22 and this measure is considered the

gold standard for self-report exercise assessment.23 Con-

sistent with previous research protocols, minutes

engaged in mild exercise were not used in these analyses,

but the category was included in the questionnaire to

ensure that participants did not report mild exercise

minutes in the moderate intensity category.24

Statistical Analysis

First, we centered the EDS scores and calculated an

interaction variable for EDS and ED status. Next, an ordi-

nary least squares regression (OLS) analyses was used to

examine the associations among exercise dependence and

ED severity on HRQOL. The interaction effect was exam-

ined because we were particularly interested in examining

the moderating influence of exercise dependence on the

relationship between ED severity and HRQOL.

Results

ED severity (ED vs nonED) was determined byscores on the EDDS. That is, the EDDS algorithm15

was followed to categorize participants into ED ornonED groups based on symptom severity. There-fore, these analyses take into account ED severity.Exercise dependence symptoms were measured bythe EDS (M 5 41.31, SD 5 16.90) and ED-specificHRQOL was measured by the EDQOL total score(M 5 0.40, SD 5 0.45). The means and standarddeviations for the EDS, EDQOL, and LTEQ for the

ED and nonED groups are reported in Table 1. Toour knowledge, EDS assessments of ED individualshave not been previously reported. Our nonEDgroup’s mean of 40.40 (SD 5 15.70) is similar to amean of 40.63 (SD 5 13.09) that has been reportedin a previous study using the EDS to assess anonED college sample.11 With regards to theEDQOL, the ED group (M 5 0.77, SD 5 0.65) in ourstudy reported scores that are in between scorespreviously reported by ED individuals with minorsymptom severity (M 5 0.53, SD 5 0.44) and mod-erate severity symptoms (M 5 1.29, SD 5 0.54) andthe nonED group (M 5 0.35, SD 5 0.40) in ourstudy reported slightly lower scores than previouslyreported scores in nonED individuals (M 5 0.42,SD 5 0.34).20 The overall model examining theimpact of ED and exercise dependence (independ-ent variables) on HRQOL (dependent variable) wassignificant [F(3,374) 5 24.92, p < .001] andexplained 16.1% of the variance in HRQOL scores(R2 5 0.097). ED severity (b 5 0.396, p 5 .001) aswell as higher exercise dependence scores (b 5

0.231, p 5 .001) both predicted more HRQOL detri-ments (see Fig. 1). Additionally, the interactionamong ED and exercise dependence was signifi-cant (b 5 0.187, p 5 .040) suggesting that the com-bined effects of ED and exercise dependencesignificantly impacts HRQOL. Thus, individualswith ED and higher exercise dependence scoresmay experience more HRQOL detriments as com-pared with individuals without an ED and with lowexercise dependence scores.

Discussion

The purpose of our study was to examine the asso-ciation among ED, exercise dependence, and

FIGURE 1. Association between exercise dependence and health-related quality of life (HRQOL) detriments of eating disorder and no eating dis-order groups. Regression lines depict the association of exercise dependence and HRQOL detriments. Increased HRQOL scores indicate more detri-ments. Exercise dependence is associated with HRQOL detriments for all groups, but this effect is more pronounced when exercise dependencesoccurs with an eating disorder. The significant interaction effect of these regressions indicates that motives (i.e., exercise dependence) may detri-mentally affect daily functioning/HRQOL, particularly for those who have an ED.

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270 International Journal of Eating Disorders 47:3 268–272 2014

HRQOL. Consistent with our hypothesis, we foundthat both ED and exercise dependence may impactHRQOL and that ED and exercise dependence alsointeract to further adversely impact HRQOL. Theseresults suggest that pathological motivations forexercise may exacerbate the detrimental impact ofED on HRQOL. Thus, our results offer insights intowhy exercise behavior may be associated with dele-terious effects on HRQOL in ED.25

Our finding of an interaction effect among EDand exercise dependence on HRQOL is importantfor at least three reasons. First, understanding ofthe psychological aspects of exercise in ED is lim-ited despite clinical reports and research suggest-ing that compulsively exercising ED individualspresent more severe symptomatology6 and higherpersistence of ED behavior.5 Thus, the interactioneffect observed in our study indicates that motives(i.e., exercise dependence) may detrimentally affectdaily functioning=HRQOL particularly for thosewho have an ED. Our finding that exercise depend-ence in the absence of ED is also associated withHRQOL detriments suggests that pathological

motivations toward exercise, but not exercise

amount, may be of interest for further research.7

Second, our results support previous recommenda-

tions to also examine psychological aspects of exer-

cise as these may be markedly more influential

than examining only exercise amount or fre-

quency.7,8,26 Finally, the use of HRQOL as an out-

come variable, rather than the presence of ED or

ED symptom severity, further describes the scope

of impairment associated with exercise in ED.

Thus, our findings of an interaction between ED

and exercise dependence suggests that future

research examining the impact of psychological

aspects of exercise in ED may be fruitful.

Our study highlights several areas for future inves-tigation; however, limitations were present. First, EDwas assessed through a self-report measure in asample of female college students that may not berepresentative of all variants of ED, allow insightsregarding exercise dependence and the severity ofED, provide a clinical diagnosis of ED, or allowexaminations of gender differences. Moreover, vali-

dation research has concluded that the sensitivity forthe EDDS indicates that some individuals withbulimia nervosa may not have been identified.14

Second, our small sample size did not allow for com-parisons between ED variants. This is importantbecause previous research has demonstrated a widerange of compulsive exercise prevalence among EDdiagnoses.5 Finally, our cross-sectional design pre-cludes causal inference into the relationships amongexercise dependence, ED, and HRQOL. Thus, ourresults should be interpreted with caution.

Our study represents an initial attempt to explorethe relationships among exercise motives, EDseverity, and HRQOL. Our finding of an interactionbetween ED severity and exercise dependence onHRQOL detriment severity suggest that futureresearch is encouraged to continue to examine psy-chological aspects of exercise (i.e., exercisedependence; exercise compulsion; obligatory exer-cise) in ED.8,11,12 Moreover, these data were col-lected as part of a larger study that did not assessother relevant ED-related variables (e.g., affectcomorbidities such as depression and anxiety), nordid we address the effect of exercise dependenceon HRQOL in relation to previous or current EDtreatment. Future research is encouraged to exam-ine the impact of exercise dependence on EDseverity, treatment, and possible differences amongED diagnosis.27 Thus, our results indicate thatfuture research is needed to further elucidate therelationship among psychological aspects of exer-cise, ED, and HRQOL.

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