While some may joke about being “addicted” to various things -- chocolate, coffee or selfies, for instance -- addiction is no laughing matter when it involves dangerous behaviors and substances. But more and more research is showing that cardiovascular exercise plays a role in addiction treatment and can reduce the inclination to experiment with these substances.
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The Brain Chemistry of Exercise vs. Addiction
The idea that exercise promotes longevity and health is not a modern discovery. Both the ancient Greeks and Romans recognized the importance of prescribing exercise for its health benefits. Though the dosage has changed over the years, a 2012 review study in the British Journal of Pharmacology reports that exercise is “one of the most frequently prescribed therapies in both health and disease.” The study concludes that exercise is so beneficial for health that it should be “considered as a drug.”
With regards to the addicted brain, Mark Smith, professor of psychology at Davidson College, says that exercise may serve as alternative non-drug reward activity, trading in an actual high for a “runner’s high.”
“When you look at how exercise affects the brain, you see that it increases dopamine in a reward pathway,” says Wendy Lynch, associate professor of psychiatry and neurobehavioral sciences at the University of Virginia School of Medicine.
Levels of dopamine and other “feel-good” chemicals are elevated by consuming the things we crave but plummet quickly when we stop. Researchers at the National Institute on Drug Abuse say that incorporating exercise into the addiction treatment process -- as well as engaging in physical activity prior to exposure -- may help in reducing substance abuse.
“The more likely you are to engage in physical activity, the less likely you are to abuse drugs,” Smith says. Smith, who has researched the behavioral effects of opioids and cocaine for the past six years, says there are a few reasons for the inverse relationship of exercise and drug use.
First, substance abuse often causes a decrease in physical activity, he says. “If you know a substance abuser, that’s their full-time job. They don’t have the discretionary time and income to engage in physical activity and exercise.” Preventing drug use might also correlate with nurture. “Maybe you were exposed to a positive role model early in life, and this positive role model encouraged you to live a healthy lifestyle,” Smith says. “Part of that involved engaging in physical activity, but part of that involved abstaining from illicit drugs.”
“Exercise increases self-esteem, self-efficacy and feelings of well-being,” Smith says. “All of these are negatively correlated with substance abuse. And all of these are protective factors against substance abuse.”
Treating the Various Stages of Addiction
Smith’s research has focused on the notion that physical activity causes a decrease in substance abuse, and in numerous studies, he has shown the powerful effects of exercise on different stages of use and relapse. He studied two groups of rats -- one sedentary group with normal lab-cage activity and one group with access to a running wheel. The rats could run as much or little as they desired. After six weeks, Smith and fellow researchers trained the rats to intravenously self-administer cocaine or heroin (or a combination of the two), and then measured how much the rats injected.
“Sure enough, the exercise group self-administered much less cocaine than the sedentary control group,” Smith says. “That was the first evidence of this cause-and-effect relationship -- that engaging in physical activity leads to a reduction in substance abuse.”
Smith ran follow-up studies that looked at the ability of exercise to reduce self-administration during different transitional stages of drug administration and drug relapse. “There are several important stages -- the first is acquisition abuse,” he says. “No one starts out as a drug addict. Some people will experiment, but most of them will not advance beyond the experiment stage.”
The second stage is maintenance, when an individual engages in regular, consistent abuse but not in a problematic manner, Smith says. “This is how many Americans use drugs -- one to two glasses of wine every single night. People do this for years and years with no problems.” The third phase is escalation -- where some people gradually increase use over time and continue to do so despite negative consequences.
“Binge use/compulsive use is typically what we think about when someone is in the worst stage of addiction,” Smith says of the fourth stage. “During these binges, there is a highly dysregulated pattern abuse, and this is where people get themselves into trouble. This is the stage associated with overdose, criminal activity and visits to the hospital emergency room.” But Smith’s lab-rat studies provide encouraging evidence that physical activity can curb or prevent drug abuse in all of these stages of the addiction process.
Lynch’s studies at the University of Virginia School of Medicine also support this conclusion, especially for the final stage -- relapse. She co-authored a study published in the September 2013 issue of Neuroscience & Biobehavioral Reviews, which showed that “physical activity and exercise activate the same reward pathway as drugs of abuse, through increases in dopamine concentrations and dopamine receptor binding.”
Lynch says that for both nicotine and cocaine, administering exercise during abstinence reduces the changes in the brain that lead to relapse, and the earlier you administer the treatment, the better. “Evidence from both human and animal literature is consistent and shows that exercise can effectively decrease the likelihood of starting and levels of abuse under a controlled situation (non-abuse),” she says. “It can prevent or reduce the likelihood of progressing to abuse or dependence, and it can reduce relapse vulnerability.”
Exercise’s Benefits Extend to Smokers Trying to Quit
Research has also shown exercise may help people quit smoking, which is good news for the 18.1 percent (42.1 million) of people 18 years and older who smoke in the United States, as reported by the Centers for Disease Control and Prevention in 2012.
Michael Ussher, a professor of behavioral medicine at St. George’s University of London, says there is “evidence from more than 30 studies that cigarette withdrawal symptoms and cravings are reduced following a single bout of exercise.” Ussher says sessions of exercise lasting five to 30 minutes have been used in these studies and the effect can last up to 30 minutes. “This evidence is the main rationale for why exercise might help smokers quit,” he says.
As for psychological effects, Ussher says smokers tend to have higher rates of depression than non-smokers, so exercise is beneficial for them because it “reduces depression and anxiety and increases self-esteem and positive mood.”
Ussher cited a study from the Center for Behavioral and Preventive Medicine that asked 281 female smokers to attend three sessions of vigorous exercise a week for a 12-week period while they were quitting. The researchers found that the smoking cessation rates were about twice as high in the exercise group compared with a control group enrolled in a wellness program.
Physical Activity for All
You don’t need to be addicted to reap the benefits of exercise, however. Smith says “moderate intensity for moderate time typically makes most people feel good.” The Centers for Disease Control and Prevention and the American Heart Association recommend at least 30 minutes of moderate-intensity aerobic activity at least five days per week or 25 minutes of vigorous aerobic activity at least three days per week. The groups also recommend moderate- to high-intensity muscle-strengthening activity at least twice a week for additional benefits.
This can include power walking, water aerobics, riding a bike on flat land or pushing a lawn mower, according to the CDC. Vigorous activities include jogging, swimming laps, riding a bike quickly or up a hill and playing basketball. Whether it’s running, playing sports or walking around the park, Smith suggests engaging in any activity you enjoy that gets your heart rate up. “That’s the exact same thing your primary care physician would tell you.”