Endorphins and Exercise Addiction

Slate has an article this weekend (Gym Rats and Dope Fiends) that discusses recent findings of a study that show exercise seems to decrease rats' susceptibility to abuse drugs in a lab setting.  This leads into discussion of whether the endorphins generated by working out are addictive or habit-forming in themselves, and studies have suggested that they are.   The "endorphin addiction" model of anorexia is the one that I've always felt most applied to my case (see Endorphins, Eating Disorders, and Other Addictive Behaviors by Hans Huebner, a bit dated by this point but still outlines the theory well).

In the early 1960s, there were 100,000 self-identified runners in the nation. By the late 1970s, there were 30 million.  It wasn't long before the ranks of psychologists and packs of joggers ran headlong into one another. More and more people were working out, and clinicians noticed that some of them were hurting themselves. What's more, their devotion to marathon training or aerobics was taking on some of the qualities of an addiction: Runners claimed to experience a "natural high," and some were steadily increasing their distances to achieve the same level of satisfaction. Scientists wondered if this had something to do with one of the body's naturally occurring pleasure peptides, the beta-endorphin, which gets released during exercise. (Endorphin is a shortened version of the "endogenous morphine.") Were runners getting "addicted" to endorphins? Sometimes they showed signs of withdrawal—increased anxiety and depressive tendencies—when they missed a visit to the track.

Soon these obsessive joggers were being described as victims of an exercise addiction, though in deference to diagnostic conservatives their affliction was also termed obligatory exercise, overtraining syndrome, or exercise dependence (the "other" ED). Some researchers felt the condition was merely an outgrowth or subset of anorexia nervosa and declared the combination of undereating and overtraining responsible for the Female Athlete Triad, or FAT. (Its three components are disordered nutrition, amenorrhea, and osteoporosis.) And since men were diagnosed as anorexics less often than women, it was further proposed that overtraining might be the masculine version of an eating disorder.

The rest of the article is well-worth reading, (although I don't totally agree with the concept of a "masculine version" of an eating disorder or with their tossing around of terms like "exorexic").  These findings and the idea of exercise addiction in general (not just with runners) are probably notably unsurprising to anyone who has ever dealt with compulsive exercise issues.  It honestly can feel like physical withdrawal when you try to slash time or even just change the routine of your workout.  Anxiety? Through the roof.  After a while on the new routine, you get "weaned" and the symptoms abate (even if you still want to work out, the anxiety symptoms aren't as intense), but at the start it's just so tempting to give in, hit the workout, get your endorphins and get along with your day feeling calmer and saner (I am NOT implying people with EDs are insane, just describing a subjective feeling about oneself from my experience), even though you've just engaged in the behaviors that are supposedly harming you.  Which reinforces the feeling that you "need" them, of course.

I've always accepted that eating disorders involve hereditary factors, and would even if it weren't for the convenient anecdote that my family tree's branches almost touch the ground because they're so heavy with alcoholics, EDers, and anxiety disorders.  They don't go into this much in the article, but an endorphin addiction model also lends support to the theory that some people have more inborn genetic susceptibility, due to different neurochemical wiring, relative receptor densities and types, etc.

Obviously, I'm speaking largely from my own experiences here. Please chime in with comments if you've dealt with this also, though, always interested to hear how overexercise has developed and (hopefully) been overcome by different people.

Slate has a couple of other fitness-related articles of interest:
-Profile of a "fitness model" that does ads for sporting goods, etc.  I liked this because they mentioned that they have to have separate fitness models because the "regular" models are too thin and don't look healthy and fit (or even "recognizably human", according to the author) enough to sell sportswear.  I also like that they don't mention her weight, her diet, etc.

-Article of how people in countries outside of the U.S. tend to get their exercise, is interesting to see how it's approached in different cultures and societies.