Excessive exercise may be linked to suicidal behavior in people with eating disorders, new research shows.
Four studies conducted by the same team of investigators suggest that overexercise is a "dangerous" behavior that is consistently related to acquired capability for suicide (ACS) and suicide attempts.
The first study, which included more than 200 women with a clinically diagnosed eating disorder — 70% of whom had bulimia nervosa — showed that "over-exercise was the only disordered eating variable that maintained a significant relationship with suicidal behavior."
The second study, which followed 171 college students, and the third study, which followed 512 college students, both showed a significant relationship between overexercise and ACS.
In the fourth study, which included 467 college students, investigators found that "pain insensitivity accounted for the relationship between over-exercise and ACS."
"These results suggest that over-exercise can be hazardous," the investigators, led by April R. Smith, PhD, from the Department of Psychology at Miami University in Oxford, Ohio, write.
The findings of all 4 studies "converge to suggest that over-exercise represents a dangerous disordered eating behavior that consistently is related to both [ACS] and suicide attempts, even when adjusting for a host of other painful behaviors," the investigators add.
The research was published April 30 in Psychiatry Research.
Suicide Attempts Common
According to the researchers, approximately one third of all women who have bulimia nervosa will attempt suicide.
One essential variable to enacting a lethal attempt, according to the interpersonal-psychological theory of suicide, is ACS. This "refers to the ability to inflict potential lethal self-harm and is attained by repeatedly subjecting the body to painful and provocative experiences," write the investigators.
In addition, past research has suggested that overexercise is associated with pain, an increase in pain tolerance, and increased levels of ACS. For the current studies, the researchers sought to investigate the relationship between bulimic behavior, exercise, and suicidal behavior.
A total of 204 women with an eating disorder who were between the ages of 18 and 57 years (90.7% white, 3.4% Asian, 2.5% black; mean age, 25.7 years) were enrolled in the first study.
Of these, 70.6% met full criteria for bulimia nervosa, whereas the remaining participants had partial syndrome bulimia. All completed the self-reported Eating Disorder Examination Questionnaire–4 (EDEQ-4), which included an item specifically asking about exercise.
The 25-item Impulsive Behavior Scale was used to measure suicidal gestures and attempts.
Results showed that 60% of the women reported undergoing hard exercise during the previous month, and 24.6% reported engaging in suicide gestures more than once.
In addition, 13.3% and 14.3% of the participants reported a suicide attempt more than once or at least once, respectively.
Even after adjusting for variables such as age, frequency of laxative use, and vomiting episodes, overexercise was significantly predictive of suicidal gestures (P = .03) and suicide attempts (P = .02).
In the second study, the investigators assessed 171 undergraduates from a college in the southeastern region of the United States (80.1% women; 87.3% white, 9.1% black; mean age, 19.3 years).
The EDEQ-4 was again used to measure eating disorder behaviors and hard exercise participation. The Obligatory Exercise Questionnaire and the ACS Scale were also used.
Results showed that overexercise, as measure by the EDEQ-4 and the Obligatory Exercise Questionnaire, significantly predicted ACS (both, P = .05).
The third study included 512 undergraduate students (80% women; 79.3% white, 14.4% black; mean age, 18.9 years). Measures included the ACS Scale–Short Version and asking about overexercise and about possible lifetime suicide attempts.
The researchers found that both overexercise and exercise duration significantly predicted ACS (P = .001 and P = .002, respectively). ACS was also significantly predictive of suicide attempts (P = .001).
Too Much of a Good Thing
Study 4 enrolled 437 undergraduates from a northern US university (57% women; 84% white, 4.3% black, 10.3% Asian; mean age, 19.6 years). Outcome measures included the EDEQ-4 and specially authored questions to assess overexercise, questions about bulimic disordered eating behaviors, the ACS Scale, and the NeuroSensory Analyzer to assess pain threshold.
Results showed that overexercise significantly predicted pain insensitivity (P = .02) and that pain insensitivity predicted ACS (P < .001).
Although all 4 studies showed an association between hard exercise and elevated ACS, the investigators note that the conclusions "are tentative" and require replication.
"Even so, these results suggest that the pain and discomfort involved in over-exercise may increase pain insensitivity. This in turn could increase one's [ACS], perhaps through a corresponding increase in pain tolerance," they add.
Therefore, they recommend that clinicians "teach healthy exercise" to patients with bulimia, especially because past research has shown that overexercise in those with eating disorders is associated with earlier relapse and a greater hospitalization length of stay.
In addition, dialectical behavioral therapy, which emphasizes the concept of balance, should also be considered, write the researchers.
Future studies should assess the mechanisms involved and how type and intensity of exercise might affect ACS, they add.
"Although exercise is often associated with beneficial effects, it appears over-exercise may have significant deleterious effects among [some] individuals."
The study authors have reported no relevant financial relationships.
Psychiatry Res. 2013;206:246-255. Abstract
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Cite this: Excessive Exercise Predicts Suicidal Behavior in Eating Disorders - Medscape - Apr 18, 2013.
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