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Three More Reasons: New Research Finds Triad of Exercise Benefits

By L. K. Regan

Lying on the sofa, thinking you might just skip the gym today? You may want to think again. That’s because several recent studies have revealed three big benefits to exercise. From your eyes to your colon to your cigarette habit, exercise just keeps giving back to you. Here’s the run-down on all the newly-discovered goodies you’re getting from your time at the gym.

Let’s begin with the windows to your soul: the eyes. Researchers at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory conducted a pair of studies on the relationship between exercise and vision. Their research, published in the January 2009 issue of Investigative Ophthalmology and Visual Science, is in fact the first to suggest that there is a direct connection between physical exercise and eyesight. One of the Berkeley studies used information from the National Runners’ Health Survey to track approximately 41,000 runners for more than seven years. It found that running reduced the risk of cataracts by 35 percent in men (women reported too few cataracts for the result to be measurable in their case). Cataracts are the U.S.’s leading cause of blindness, and affect over 50 percent of people over the age of 65. A simple prevention measure in the form of exercise would be a huge discovery.

Likewise, a second study from the Lawrence Berkeley National Laboratory found, by studying 152 people diagnosed with age-related macular degeneration, that exercise had beneficial effects for this disease as well. Age-related macular degenaration is the leading cause of irreversible vision loss in people over 65 years old, impacting 28 percent of that population, and is effectively untreatable. This smaller study found a 42 to 54 percent reduction in risk of the disease for those who regularly vigorously exercised. “In addition to obtaining regular eye exams, people can take a more active role in preserving their vision,” says Paul Williams, the Livermore Lab epidemiologist who conducted the research. “The studies suggest that people can perhaps lessen their risk for these diseases by taking part in a fitness regimen that includes vigorous exercise.”

Now, on to your colon. Your colon likes exercise. In fact, according to a survey of published studies, conducted by researchers from the Washington University School of Medicine, St. Louis and Harvard University, and published in the February 10th edition of the British Journal of Cancer, your colon likes a lot of exercise. As the researchers report, though a relationship between exercise and reduced risk of colon cancer is long-since established, no one had, until now, had a reliable estimate of how much exercise impacted the deadly cancer. Using analysis of the existing studies on the subject, 52 of them going back to 1984, and coordinating their results, the St. Louis and Harvard researchers found that people who exercise the most reduce their risk of colon cancer by 24 percent. What constitutes “exercising the most”? Well, that varied from study to study—but, as lead study author Kathleen Wolin of Washington University points out, this is a strength of the research. "What's really compelling is that we see the association between exercise and lower colon cancer risk regardless of how physical activity was measured in the studies," she says. “That indicates that this is a robust association and gives all the more evidence that physical activity is truly protective against colon cancer.” Since over 100,000 Americans are diagnosed with colon cancer each year (it is the third most common kind of cancer), hitting the gym hard and regularly could potentially save 24,000 people per year from a very unhappy diagnosis. Now, that is motivating!

Finally, for anyone looking to quit smoking, here is some seriously good news. A study in the journal Psychopharmacology from November 2008 shows that cigarette cravings can be sharply curbed by exercise. This is not the first research to suggest that exercise has a moderating effect on nicotine addiction—but it may well be the coolest. To conduct the study, the researchers from the University of Exeter had 10 regular smokers spend 10 minutes on an exercise bike after 15 hours without smoking. They then gave the men fMRIs—scans of shifting blood flow in the brain—while having them look at images. Among the images: cigarettes. For a control, the same 10 smokers underwent the same entire procedure, minus the exercise. Both times they were also asked to report on their experience of cravings. The results were intense. In response to the images, the no-exercise fMRIs had increased activity in areas of the brain associated with reward-processing and visual attention. For the post-exercise fMRIs, those same areas did not light up. Furthermore, the smokers reported lower cravings for cigarettes after exercise compared with their cravings after being idle. Why this effect is found is unclear. Researchers think exercise elevates mood hormones, which in turn reduce the need for a cigarette to do the same. Or, the workout may alter blood flow in the brain such that the regions involved in anticipation of reward and pleasure are less activated. Either way, the point is clear. Exercise should be part of any smoking-cessation program.

The researchers do not know exactly what caused the difference in brain activity following exercise. One suggestion is that completing exercise raises mood (possibly through increases in dopamine) which reduces the salience or importance of wanting a cigarette. Another possibility is that exercise causes a shift in blood flow to areas of the brain less involved in anticipation of reward and pleasure generated by smoking images. According to Kate Janse Van Rensburg, lead author on the paper, “Our findings add to a growing body of evidence suggesting that exercise can help people give up smoking. This strengthens the argument that moderate exercise could be a viable alternative to many of the pharmaceutical products, such as nicotine patches, for people who want to give up smoking. A ten or fifteen minute walk, jog or cycle when times get tough could help a smoker kick the habit.” From there, you just take it one day at a time.