By Astrid Van Den Broek
Spring 2004, Vol 7 No 3
Consider the much-respected marathoner. That tall lanky type who, at the peak of training, is logging 50 kilometres a week in runs. He’s intimately familiar with “runner’s high,” that euphoric feeling that comes with running, making him feel like king of the world. But let’s also consider another type of runner, one who prefers to run ultra-marathons and other 100+-kilometre races. Maybe she’s logging 20 kilometre runs. And that’s every day. She finds herself increasing that daily mileage, pushing herself harder and harder every day. Don’t try to make plans with her socially…. Well, you might be able to, but they’re centred around her runs. Because if she gets caught late in a meeting, or if family commitments mean she can’t make that early-morning run, she’s irritable, angry, perhaps even anxious because she missed her run.
Is this runner addicted? Merely obligated? How about compulsive? And therein lies the conundrum with exercise addiction: Does it exist? And if so, should it have its own diagnostic classification? Some say exercise as an addiction does exist because its symptoms match those experienced by people addicted to substances. Others feel more comfortable framing it as a compulsion rather than an addiction, while still others think it doesn’t fit into the confining language of addiction. Either way, are we merely getting tripped up on language when it comes to exercise addiction?
The concept of exercise as an addiction is far from new. Two popular books published in 1976 introduced the concept of addiction to running and the runner’s high: William Glasser’s Positive Addiction and Thaddeus Kostrubala’s The Joy of Running. Glasser referred to running addiction as positive to differentiate it from the classic negative addictions to substances such as alcohol and other drugs. Since then, studies have looked at exercise addiction, and the popular press features articles like, Are you addicted to exercise? Do you have exercise anorexia? “Different terms are used, but it remains a popular concept,” says Michael Sachs, a kinesiology professor at Temple University in Philadelphia, Pennsylvania. “It’s seen as a badge of honour that you’re so committed to exercise. You say you’re addicted, and that it’s good for you. How can being addicted to exercise be bad for you?”
But it’s actually quite clear how excessive exercise could be unhealthy. Key components of what some call exercise addiction include psychological withdrawal symptoms – tension, irritability, restlessness, suffering, anxiety and discomfort, to name a few. There are also physiological withdrawal symptoms such as listlessness, sleeplessness, headaches, stomach aches and a bloated feeling, says Sachs. Other qualities associated with exercise addiction are loss of control over the activity, increasing tolerance for the activity and frequency issues. Sound familiar? Switch the term “exercise addiction” with “substance addiction” – the symptoms are almost identical. Also consider some of the evidence. Stefan Brené, an assistant professor with the department of neuroscience at the Karolinska Institute in Stockholm, Sweden, is studying the running habits of rats. “I can get them to run 10 kilometres a day, which is a far distance for such an animal, and this is not a normal behaviour for the rest,” says Brené. “There are similarities (to a substance addiction), and some of the same pathways in the brain are activated, both in the rewarding effects of running and in being addicted to substances.”
At the Oregon Health and Science University in Portland, Oregon, Justin Rhodes, a post-doctoral fellow in the Department of Behavioral Neuroscience, has been working in a similar area. In his study, mice have been bred to run on voluntary running wheels over generations, in this case, it’s 12 kilometres a day. When these mice were prevented from running, their brains were stained with a protein indicating neural activities when they would have been running. “We found that many of the same brain regions came up as those activated when you prevent mice from getting their daily fix of substances, the same kind of pattern in drug abuse research,” says Rhodes.
While most agree there’s sound evidence of a physical addiction or compulsion, the inconsistency comes in the form of language. “The study of substance abuse was what first helped us develop ideas and models of addiction,” says Wayne Skinner, clinical director of the Addiction Program at the Centre for Addiction and Mental Health in Toronto. “As our ideas of addiction have expanded to include behaviours beyond drug use, it has challenged us to define just what addiction might be.”
The key drugs in understanding addiction have historically been alcohol and heroin, substances whose addictive experience is marked by tolerance and withdrawal. “Those features have produced bio-psychological syndromes of drug dependence, and that’s what was originally meant by addiction,” says Skinner. But with drugs such as cocaine and behaviours such as gambling, that framework isn’t so helpful because the same aspects of tolerance and withdrawal aren’t present. “There are syndromes of problematic behaviour there, but the original model derived from alcohol and heroin and didn’t fit that well,” explains Skinner. “So when we move away from definitions of addiction and dependence that are tightly defined and start to look at addiction as a larger phenomenon, as a metaphorical idea, we get onto a slippery slope,” says Skinner. For those who prefer science-oriented language, it gives them cause for concern. “As the use of addiction as a concept expands, we need to ask whether addiction is still a useful idea,” says Skinner. “Addiction now starts to be applied to any behaviour that becomes defined as excessive or problematic. This wide-open use sees addiction as the how of behaviour – continuing with a behaviour in spite of mounting negative consequences.”
Exercise dependence is something that Dr. Diane Bamber, a researcher in the Developmental Psychiatry Section of the University of Cambridge in the United Kingdom, has examined, largely in the context of eating disorders. One 2000 study published in the British Journal of Sports Medicine questioned almost 200 adult female exercisers about psychological morbidity, self-esteem, weight and body shape dissatisfaction, personality and exercise beliefs. The study concluded that without an eating disorder, women pegged as exercise dependent did not have “the personality characteristics and levels of psychological distress that warrant the construction of primary exercise dependence as a widespread pathology.” Another 2000 study by Bamber, also published in the British Journal of Sports Medicine, explored the idea of exercise dependence and concluded: “Where exercise dependence was manifest, it was always in the context of an eating disorder, and it was this co morbidity, in addiction to eating disorders per se, that was associated with psychological distress.” The data, Bamber concluded, supported the idea of secondary, rather than primary, exercise dependence. “It sounds like we’re playing with words,” says Rhodes. “What is dependence? The traditional definition of addiction is that you’ve developed tolerance, so you need to exercise more or take more drugs to get the same effect. We see that in our mice, because they run more each day and it keeps increasing. I also think the problem with humans is what constitutes an addiction is not clear. To what degree is it? Someone who runs six miles a day isn’t an addict, but someone who runs maybe 20 miles a day, that seems to be a loss of control,” says Rhodes.
So if the issue looks as murky as it seems, where does that leave us? “In psychiatric terms, terms such as compulsion and obsession define problems usually located in the domain of anxiety and impulse control disorders,” says Skinner. Those are important aspects, but it doesn’t say it all. There are many behaviours people engage in over and over; but it is the persistence of the behaviour when it is harmful that makes it addiction. Another feature of addiction is a narrowing of interest so that a single behaviour becomes the only way to get pleasure. “Running 20 miles a day could for some be a sign of loss of control, while for others, it could be a demonstration of amazing personal control and self-mastery,” says Skinner. “It’s not the behaviour per se, it’s what the behaviour means and what its effects are. That’s why strictly biological views of addiction will never really help us understand it as a human behaviour. You have to look at the psychological and social dimensions as well.”
25,222 consecutive sit-ups in 11 hours, 14 minutes by Richard Knecht, age 8, in 1972
non-stop: 10,507; Minoru Yoshida (Japan), October 1980
one year: 1,500,230; Paddy Doyle (Great Britain), October 1988– October 1989
24 hours: 46,001; Charles Servizio (United States), April 24–25, 1993
1 hour: 3,877; Bijender Singh (India), September 20, 1988
352.9 miles in 121 hours, 54 minutes by Bertil Jarieker of Sweden, May 26–31, 1980
“As our ideas of addiction have expanded to include behaviours beyond drug use, it has challenged us to define just what addiction might be.”
Researchers at the Georgia Institute of Technology and the University of California have found a link between cannabinoids and the runner’s high. In a 2003 study published in NeuroReport, researchers found extremely high levels of a naturally produced cannabinoid called anandamide in runners and cyclists who exercised at a moderate intensity for an extended period. Anandamide produced virtually the same effect as THC, the psychoactive component of marijuana. The researchers suggest that what these exercisers experience is not an endorphine-fuelled runner’s high, but a naturally occurring cannabinoid high.Cannabinoids produced by the body are called endocannabinoids, and are believed to have evolved primarily for pain modulation. Pain or stress kick-starts the system and helps the body modulate for pain. The researchers believe the human body begins to produce high levels of endocannabinoids – and thus a natural “runner’s high” – during moderate-to-intense exercise that produces prolonged stress and pain.