Role of Exercise in AN and Exercise Dependence

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Role of Exercise in AN and Exercise Dependence

• Vanessa Scaringi
• October 5,2005

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Overview

• First we will talk about the animal model of
  activity based anorexia
• Then relate this to hyperactivity in AN patients
• Further discuss exercise addiction in AN patients
• Also discuss exercise dependence without AN

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Activity Based Anorexia in Rats

• Semi-starvation induced hyperactivity and
  activity anorexia
• How it works in the rats
• Rats assigned to groups (access to running wheel
  and no access to running wheel)
• Food is restricted by limiting the amount of time
  the rats can eat (allowed to eat 2 hrs a day
  during the dark phase)
• What occurs is that the rats without access to a
  running wheel manage to regulate their weight
• The rats with the access to a running wheel will
  still eat the same as the others, but they lose
  weight much quicker because of their increased
  activity
• (Dixon et al)

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Importance of a study with Female Rats

• Previous studies used male rats (despite majority
  of eating disorders occur in women)
• Estrus cycles were examined prior to food
  restriction in order to look at how estrus cycles
  were affected after weight loss
• Looking at estrus cycles is crucial with female
  rats and their food intake because female rats
  naturally decrease food intake and increase
  locomotor activity during estrus phases
• At the beginning of this study all of the rats
  had regular 4 day estrus cycles
• (Dixon et al)

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The procedure

• Aside from assigning the rats to groups
• Prior to food restriction the rats were monitored
  while they went through an adaptation process
  (which included exposure to the wheel)
• Diestrus 1 was the first day of food restriction
• The rats food intake, wheel running, body
  weight, and estrus phase cycles were monitored
  until rats lost a total of 25 of body weight or
  8 days of food restriction because weight loss
  varied
• (Dixon et al)

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Results

• The rats that do not have access to a wheel will
  eventually stabilize their weight
• Intervention must occur with the rats that have
  access to the wheel. If not they will keep losing
  weight and eventually die.
• Estrus cycles were disrupted
• (Dixon et al.)

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What the animal models suggest

• Exercise and self starvation combined may have
  reinforcing qualities
• Activity may have reinforcing qualities in rats
• The combination of physical activity and self
  starvation may create a cycle with addictive
  qualities
• Interesting about preadaptation to the wheel-
  increases exercise in the food restricted rats
  and contributes to the rapid weight loss
• (Klein et. al)

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Hyperactivity in Patients with AN

• Interests clinicians because it seems impossible
  that a body so wasted can undergo such excessive
  activity
• Researchers tried to study AN patients physical
  activity levels
• Measuring activity Pedometer
• Result of this measurement showed that
  hospitalized patients with AN walked more than
  the healthy controls
• (Hebebrand et al.)

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Characteristics of excessive exercisers with AN

• Often describe their activity as more extensive
  and disorganized during weight loss (this relates
  to the animal model)
• One study showed that 75 of a group of patients
  reported an inverse relationship between food
  intake and activity levels
• Most patients state that their exercise went from
  enjoyable/recreational to obsessive and out of
  control
• (Hebebrand et al.)

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Exercise Addiction Study

• It is known that exercise has reinforcing
  qualities in humans
• Things like a runners high are associated with
  experiences of drug use (lack of pain)
• This along with other research that has suggested
  withdrawal symptoms from exercise creates the
  thought that it could be addictive like drug use
• This was 1st study of its kind
• The research done on exercise addiction in
  patients with AN actually used a substance abuse
  scale (modified for exercise) to measure the
  addiction
• (Klein et. al)

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Exercise Addiction Study in patients with AN

• 48 of the women with AN surveyed displayed
  symptoms consistent with a dependency on exercise
• This number is consistent with the estimate by
  Brewerton that 39 of AN patients engage in
  physical activity at the onset of treatment
• Lifetime prevalence could be way higher (78)
• It is thought that exercise dependence could be
  cyclical, similar to purging in AN

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Limitations to the Study

• Certain questions (ie withdrawal) would not
  pertain to someone who did not stop exercising.
• Survey mainly asked about exercise routines, the
  subjects may have engaged in other forms of
  compulsive activity.
• Within this survey they limited participants
  based on their habits the month before admittance
  into the clinic. This could have eliminated
  subjects that were exercising compulsively prior
  to that time.
• All of these limitations lead to an
  underestimation of exercise dependence among
  these women
• (Klein et al.)

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Exercise Dependence

• Can be defined as a craving for physical
  activity, resulting in uncontrollable excessive
  exercise behavior, that manifests in
  physiological (tolerance/withdrawal) and/or
  psychological (anxiety) symptoms.
• Has been suggested that the DSM categorize
  exercise dependence by having 3 or more of the
  following tolerance, withdrawal, intention
  effects, loss of control, time, conflict, and
  continuance
• Continuance is important in dealing with eating
  disorders because it means that the individual is
  continuing an exercise regimen despite physical
  problems
• (Hasenblas Downs, Adams et al.)

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DSM IV Diagnosis
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Testimonies of Exercise Dependence

• Jennifer Schmid (Dying to be Thin Video)
• Student counselor discusses her addiction
• These both could probably qualify as exercise
  dependence.

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A meta-analysis on exercise dependence

• Research on this topic has been minimal
• Some interesting aspects so far
• Hard to find people to give up exercise regimen
  to participate in a study
• Originally thought to be variant of anorexia
  nervosa, but now being researched and thought of
  as its own entity which can later become anorexia
• Exercise withdrawal symptoms are thought to be
  crucial in identifying exercise dependence
• (Hasenblas Downs)

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Physiological Factors w/ exercise dependence

• Theories suggested so far
• Similar to the opponent process model of
  dependence with drugs
• Theory where exercise mimics actions of opiate
  drugs
• In this theory exercise acts as a stimulant
• (Thomas Blanton, Koob et. Al)

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Summary

• Discussed the animal model for activity based
  anorexia
• Related this to excessive exercise or exercise
  addiction in AN patients
• Also talked about exercise dependence in general
  (DSM classification)

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The bottom line is

• Everything in moderation is key to staying
  healthy!!!

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References

• Adams, J. M., Miller, T. W., Kraus, R. K. (2003).
  Exercise dependence diagnostic and therapeutic
  issues for patients in psychotherapy. Journal of
  Contemporary Psychotherapy, 33, 2.
• Dixon, D. P., Ackert, A. M., Eckel, L. A. (2003).
  Development of and recovery from activity based
  anorexia in female rats. Physiology Behavior,
  80, 273-279.
• Hausenblas, H. A., Symons Downs, D. (2003).
  Exercise dependence a systematic review.
  Psychology of Sport and Exercise, 3, 89-123.
• Hebebrand, J., Exner, C., Hebebrand, K.,
  Holtkamp, C., Casper, R. C., Remschmidt, H.,
  Herpertz-Dahlmann, B., Klingenspor, M. (2003).
  Hyperactivity in patients with anorexia nervosa
  and in semistarved rats evidence for a pivotal
  role of hypoletinemia. Physiology Behavior, 79,
  25-37.
• Klein, D. A., Bennett, A. S., Schebendach, J.,
  Foltin, R. W., Devlin, M. J., Walsh, B. T.
  (2004). Exercise addiction in anorexia nervosa
  model development and pilot data. International
  Journal of Neuropsychiatric Medicine, 9, 531-537.