Excessive exercise (EE) is common among eating disorder patients. Indeed, in the study I’ll write about today, 39% of patients engaged in EE. Previous studies have tried to find psychopathological and personality correlates of EE but the results have been inconsistent. Some studies have suggested that impulsivity and addictiveness are highly correlated with EE whereas others found that anxious and depressive traits were more closely associated.
In a retrospective case series study involving outpatients with AN and BN, Penas-Lledo et al. found higher levels of anxiety and depression… among those who were identified as exercising excessively. The authors claimed that exercise might serve to reduce anxiety and stress in individuals with AN. In a similar study with adolescent inpatients with AN, Holtkamp et al. found that anxiety significantly predicted variance in exercise levels. These investigators proposed that anxiety symptoms in combination with food restriction contributed to increased levels of physical activity and that physical activity served an anxiolytic [anxiety reducing] function.
In this multi-site study, Shroff and colleagues wanted to examine the prevalence of EE across eating disorder subtypes and the personality traits and clinical variables that were associated with EE in a large sample of women (1,857 in this study).
But first, what exactly is “excessive exercise”?
Although there have been numerous studies of exercise and excessive activity in eating disorders, there is no consensus on what constitutes excessive exercise with definitions varying in frequency of hours, definitions of unhealthy preoccupation with exercise, and discomfort experienced when unable to exercise—or exercise “craving.”
In this study, participants were deemed to be excessive exercisers when they endorsed at least one of the following with regard to exercise: “(1) severe interference with important activities; (2) exercising more than 3 h/day and distress if unable to exercise; (3) frequent exercise at inappropriate times and places and little or no attempt to suppress the behavior; and (4) exercising despite more serious injury, illness or medical complication.”
PREVALENCE OF EXCESSIVE EXERCISE ACROSS ED SUBTYPES
Shroff et al. found that EE was more common among purging-type anorexia nervosa patients and least common among purging-type bulimia nervosa patients. (As a side note, non-purging bulimia nervosa means that patients binge but compensate through exercise, laxatives, diuretics, or fasting, as opposed to vomiting.)
You can see the results for all subtypes in the table below:
While I’m not surprised that patients with purging-type AN had the highest prevalence of EE, I would’ve also expected a higher EE prevalence among non-purging BN patients. I would’ve also predicted that non-purging BN patients would have a higher EE prevalence than purging-type BN patients. Having said that, although I never fit the criteria for EE by this study’s definition, I came closest during periods when I was restricting or bingeing/purging but considerably underweight, not when I was bingeing/purging at a normal weight (ie, bulimic).
FEATURES ASSOCIATED WITH EXCESSIVE EXERCISE
Next, Shroff and colleagues compared the “no/regular exercise” and “excessive exercise” groups, irrespective of their diagnosis. I summarized the differences they found in the table below:
EE was associated with high scores on anxiety measures, persistence, and perfectionism and lower scores on novelty seeking. Excessive exercise was also associated with increased eating disorder severity (measured by evaluating rituals, food/weight preoccupation and motivation to change). This is not surprising (to me) because EE can be seen as way of self-harm, and so I’d hypothesize that patients who engage in EE probably exhibit worse ED psychopathology. Excessive exercisers also had higher levels of obsessions and compulsions.
With regard to the finding that EE was most prevalent among the purging-type anorexia nervosa subgroup, the authors noted “previous research showing that this subgroup is particularly prone to anxious and harm avoidant traits.” Perhaps these traits somehow “feed into” excessive exercise or maybe exercise is a way to cope with the anxiety?
In a study with adolescent patients with AN, Davis et al. found that, compared with controls, patients reported engaging in more exercise during the year before the onset of their illness. Thus, it may be that individuals who are particularly prone to anxious obsessionality are more likely to engage in ‘‘extra’’ eating disorder behaviors (e.g., purging and excessive exercise) that are driven by their fear, anxiety, and obsessive preoccupation with weight gain.
An alternative explanation may be that exercise served to reduce or manage anxiety as postulated by Holtkamp et al. or to counteract prominent eating and weight related obsessions.
The authors hypothesized that the genes or neural pathways that predispose individuals to anxiety and excessive exercise may be linked. Or perhaps for this subset of individuals, exercise is just the most biologically sensical way to decrease anxiety:
Favaro et al. found significantly higher tryptophan to large, neutral amino acids (TRP-to-LNAA) ratios among those who exercised excessively. These investigators postulated that exercise helped to counteract the reduction of TRP/LNAA and serotonin synthesis, potentially functioning as a form of ‘‘self medication’’ to balance the levels of TRP/LNAA in the body.
These findings suggest that physical activity and weight regulation may, in fact, represent endophenotypes [what’s an endophenotype?] for eating pathology that contribute to its etiology, particularly the etiology of eating disorders characterized by high perfectionism, anxiety, ritualistic behaviors, obsessiveness, and purging behaviors.
From a clinical standpoint, EE seems to be associated with a number of features that might make treatment more difficult, such as increased eating disorder severity and lower BMI values. Understanding what drives EE in eating disordered individuals and who is predisposed to develop EE might aid in designing successful treatment interventions in the future.
Though keep in mind, this study was published 7 years ago–yes, “latest” is a flexible term around these parts–and I haven’t done a thorough search of what’s been published since, except I checked out the papers that cited this one.
However, there was a paper published in 2012 that suggested over-exercise is associated with suicidality in individuals with disordered eating (I plan to blog about this in the future). So there’s even more reason to study EE and its relationship with eating disorders in terms of causes, associations, and possible treatments.
I should also make it clear that in my mind, excessive exercise has got almost nothing to do with how much you exercise but your attitude toward exercise. My attitude toward exercise was at its worst when I was probably running only 25km/week, but if I missed a day, I’d panic, cry, and experience debilitating anxiety. I also wouldn’t listen to my body. Many years later, when I was training for the full marathon, I was running 70-80km a week and biking another 100-150km. I had no anxiety at ALL when I didn’t exercise, took days off when I felt I needed them, and carefully made sure I had no injuries, trained safely, and ate to fuel my runs.
Readers, have you ever exercised excessively (according to the definition in this paper, or in other papers)? During what stage of your eating disorder was the exercise at its worst? Do you have a sense of why you did it or why you were compelled to do it?
Shroff, H., Reba, L., Thornton, L., Tozzi, F., Klump, K., Berrettini, W., Brandt, H., Crawford, S., Crow, S., Fichter, M., Goldman, D., Halmi, K., Johnson, C., Kaplan, A., Keel, P., LaVia, M., Mitchell, J., Rotondo, A., Strober, M., Treasure, J., Blake Woodside, D., Kaye, W., & Bulik, C. (2006). Features associated with excessive exercise in women with eating disorders International Journal of Eating Disorders, 39 (6), 454-461 DOI: 10.1002/eat.20247