Some people would rather miss a meal or their favorite television show than miss a workout. You probably know some runners who refer to their passion for running as an “addiction.” Some bodybuilders approach their weight training sessions with the same degree of enthusiasm. To miss a workout to them would be worse than missing a night of sleep. When people who exercise say they’re addicted, is there any science behind it? Can exercise be addicting?
Is Exercise Addictive?
You’ve probably heard of the “runner’s high.” Runners claim that after they’ve run a certain distance they experience a feeling of euphoria. It’s this feeling that motivates some runners to keep pounding the pavement. This type of feeling isn’t necessarily confined to runners. People who do high-intensity aerobic workouts describe a similar phenomenon.
Scientists believe the runner’s high comes from the release of endorphins, powerful chemicals with morphine-like properties that attach to receptors in the brain and exert their mood-elevating effects. These chemicals elicit pleasurable sensations similar to what happens when a person takes morphine. Some runners even describe an almost surreal sense of peace and oneness with things around them when they experience a runner’s high. Research has found people have higher blood levels of endorphins during and after an exercise session.
Exercise May Affect Brain Chemicals That Alter Mood
There is evidence in animals that exercise is addictive. Researchers discovered that rats that exercise by spinning in a wheel have brain chemical changes similar to those induced by morphine. Levels of the neurotransmitter dopamine rise and other opioid-type pain-blocking proteins are released when they spin in their wheel.
Researchers injected a group of compulsively exercising rats with a drug called naloxone. Naloxone is used to treat morphine addiction since it blocks the effects of opioids on the brain. The rats that received naloxone experienced symptoms similar to those seen in morphine withdrawal, although not as pronounced. So there may be some truth to the statement, “If I miss a workout it sends me into exercise withdrawal” that you hear hardcore exercisers proclaim.
Exercise and Chocolate Have Something in Common
There’s another chemical called phenylethylamine that boosts mood and increases energy levels. In a study carried out at Nottingham Trent University, researchers found that men who exercised on a treadmill at a moderate intensity had higher levels of this mood-elevating chemical in their bloodstream after they finished. Interestingly, phenylethylamine is also found in chocolate. So, it may be more than endorphins that motivate people to keep working out. Exercise may cause a variety of biochemical changes that make it addictive in a sense.
Exercise Addiction Can Be Good or Bad
The good feelings that come from working out can motivate you to keep doing something healthy. On the other hand, exercise addiction can become harmful when it leads to overtraining and when it’s associated with other maladaptive behaviors such as eating disorders. There may be some truth to the idea that exercise is addictive. But at least in moderation, it’s a healthy addiction.
References:
Serendip.com. “Exercise and the Runner’s High: Can It Really Make You Happy?”
Addiction Research and Theory. 10:415-437. 2002.
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How High-Intensity Exercise Makes Your Brain More Efficient
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Exercise is Good for Your Brain as Long as You Make It a Habit
