Exercise may lower a woman's risk of breast cancer by affecting the way her body breaks down estrogen, according to a new study in the journal Cancer Epidemiology, Biomarkers & Prevention.


Researchers from the University of Minnesota said that observational studies have long shown associations between lowered breast cancer risk and increased exercise, but we had little information as to why this may be the case.


"Ours is the first study to show that aerobic exercise influences the way our bodies break down estrogens to produce more of the 'good' metabolites that lower breast cancer risk," study researcher Mindy S. Kurzer, Ph.D., a professor in the university's food science and nutrition department, said in a statement.


The study included 391 healthy premenopausal women who led sedentary lifestyles; 179 of them were put in a control group where they just kept living a sedentary lifestyle, while 212 were placed in an exercise group where they did 30 minutes of aerobic exercises (moderate to vigorous level, such as running on a treadmill or using the elliptical machine) five days a week for four months. Of all the women in the study, 78 percent of those from the exercise group and 86 percent of those from the control group completed the study.


Researchers took urine samples of the women for three days before the study began, in order to measure three estrogens and their metabolites (the product that remains after the estrogens are broken down). Researchers knew beforehand that a particular ratio of one kind of estrogen metabolite with another is linked with having a lower risk of breast cancer.


Indeed, researchers found that the women who were assigned to the exercise group experienced an increase in this protective estrogen metabolite ratio, while the ratio didn't change at all for those who remained sedentary.


ABC News previously reported on research published last year showing links between exercise and breast cancer risk; the news organization noted that the association may be because exercise decreases weight, and there is a lot of estrogen that arises from fat tissue. For more on that research, click over to ABC News.


Also on HuffPost:






  • Improved Sexual Function


    Here's a motivating reason to get moving: regular physical activity can increase blood flow in a way that has a direct affect on sexual function, explains <a href="http://www.huffingtonpost.com/david-katz-md" target="_hplink">HuffPost blogger</a> David Katz, M.D., founding director of Yale University's Prevention Research Center At Griffin Hospital.

    In fact, a recent study published by Emory University researchers in the <em>Journal of Sexual Medicine</em> identified a link between physical activity and erectile function among men between the ages of 18 and 40.

    "The men in our study who exercised more seemed to experience a protective benefit against erectile dysfunction," study co-author Wayland Hsiao, assistant professor of urology at Emory School of Medicine, <a href="http://www.emory.edu/EMORY_REPORT/stories/2012/01/research_exercise_enhance_sexual_function_men.html" target="_hplink">said in a statement</a>. "We hope that early screening for ED may be a gateway issue to help motivate young men to live healthily on a consistent basis so that they can possibly avoid health issues associated with a sedentary lifestyle, such as diabetes and cardiovascular disease. We see this as just the beginning."




  • Changes In Gene Expression


    In the burgeoning field of epigenetics, scientists are discovering how <a href="http://www.time.com/time/magazine/article/0,9171,1952313,00.html" target="_hplink">environmental factors</a>, including diet, stress and toxins, can change the way our genes are expressed, essentially turning certain genes on or off, and affecting which are passed down from generation to generation.

    One factor that can play a role? Exercise. Two recent studies have illustrated just how regular physical activity can affect gene expression.

    The first study, conducted by Swedish researchers illustrated how inactive young adults demonstrated an immediate shift in their muscle cells' genetic material after just a few minutes on a stationary bicycle, <a href="http://www.huffingtonpost.com/2012/03/06/exercise-changes-your-dna_n_1324452.html" target="_hplink">HuffPost reported</a> when the findings were released.

    The second study, conducted by researchers from the Harvard School Of Public Health, found that walking an hour a day can <a href="http://www.huffingtonpost.com/2012/03/15/walking-obesity-genetic_n_1345224.html" target="_hplink">slash genetic tendencies toward obesity</a>. We'll walk to that!




  • Better Skin


    Sweating it out could help you get your glow on post-workout, too. As Dr. Katz explains, your skin is the largest organ in your body. And as we slough off tons of skin cells each day, we need to give our body the right construction materials -- healthy foods, regular exercise, plenty of oxygen -- to rebuild. " If you've got good construction material," he says, "you can build healthy skin cells and you have good skin."

    Skin also tells the story of what's going on inside your body. "The skin is the window dressing. It's really reflective of overall health," Katz says. And that means if your body's natural detoxification system is healthy, including the kidneys, liver and spleen, it'll translate into a healthy looking glow.

    Those body-sculpting benefits of working out don't hurt either. "Skin draped over muscle looks great, skin draped over an excess of subcutaneous fat, not so much," Katz says.




  • Healthy Eyes


    Here's a health shocker: moving your feet may have health benefits all the way up to your eyes.

    According to a recent paper published in the journal <em>Investigative Ophthalmology & Visual Science</em>, <a href="http://www.sciencedaily.com/releases/2011/10/111024133028.htm" target="_hplink">regular exercise may be linked</a> to a lowered risk of developing glaucoma.

    Researchers, evaluating 5,650 men and women between the ages of 48 and 90, found that people who engaged in moderate physical exercise 15 years prior had a <a href="http://www.ahaf.org/glaucoma/newsupdates/physical-fitness-could-have-a.html" target="_hplink">25 percent reduced risk</a> of low ocular perfusion pressure, a risk factor for glaucoma.

    "It appears that OPP is largely determined by cardiovascular fitness," author Paul J. Foster, M.D. Ph.D., of the University College London Institute of Ophthalmology <a href="http://www.sciencedaily.com/releases/2011/10/111024133028.htm" target="_hplink">said in a statement</a>. "We cannot comment on the cause, but there is certainly an association between a sedentary lifestyle and factors which increase glaucoma risk."




  • Better Sleep


    Breaking a sweat during the day may just mean better beauty sleep at night. According to a large study published last year in the journal <em>Mental Health and Physical activity</em>, people who exercised at a moderate or vigorous level for at least 150 minutes a week (that's just over 20 minutes a day) <a href="http://www.sciencedirect.com/science/article/pii/S1755296611000317" target="_hplink">reported 65 percent better sleep quality</a> than their more sedentary peers.

    "Increasingly, the scientific evidence is encouraging as regular physical activity may serve as a non-pharmaceutical alternative to improve sleep," study author Brad Cardinal, a professor of exercise science at Oregon State University <a href="http://www.sciencedaily.com/releases/2011/11/111122143354.htm" target="_hplink">said in a statement</a> when the findings were released.

    And that, in turn, could have a whole host of additional benefits, as <a href="http://www.huffingtonpost.com/2011/11/28/exercise-sleep-quality-moderate-weekly_n_1116315.html" target="_hplink">poor quality sleep</a> has been linked to increases in inflammation, high blood pressure, and increased blood glucose levels in people diagnosed with Type 2 Diabetes.




  • A Sharper Brain


    Looking at your body holistically, what's healthy for the whole body -- good nutrition, plenty of rest, supportive relationships -- is also good for the brain, explains Katz. And the same goes for regular exercise.

    "If something is good for your brain, it's probably good for you," he told The Huffington Post. "And if it's not good for you, it's probably not good for your brain."

    In the short term, exercise means increased blood flow to the brain, which can help you stay sharper. So instead of taking that coffee break, which provides an artificial stimulant to help you focus in the short-term, consider a walk instead. "Exercise does the same thing and it confers a lasting benefit into the bargain," he says. (Added bonus: <a href="http://www.huffingtonpost.com/2012/01/13/sitting_n_1202800.html#s608680&title=It_Ups_Diabetes" target="_hplink">sitting for too long</a> has been associated with a host of health problems, including increased diabetes and cancer risk.)

    In fact, one Swedish study published last year in the <em>Journal of Occupational and Environmental Medicine</em> found that taking exercise breaks at work for two-and-a-half hours a week was associated with improvements in productivity.

    Physical fitness also has brain benefits in the long term, as well. Studies have linked regular activity to <a href="http://www.sciencedaily.com/releases/2011/09/110907163919.htm" target="_hplink">decreased risk of dementia</a> and <a href="http://www.webmd.com/fitness-exercise/news/20070313/get-fit-improve-memory" target="_hplink">improved memory</a>.




  • Fewer Migraines


    Roughly 36 million people in the United States suffer from migraines, <a href="http://www.migraineresearchfoundation.org/about-migraine.html" target="_hplink">according to the Migraine Research Foundation</a> -- and the oftentimes debilitating headaches take their toll in more than 113 million lost work days each year.

    Characterized by <a href="http://www.mayoclinic.com/health/migraine-headache/DS00120" target="_hplink">intense pain in one side of the head</a> and often joined by symptoms of nausea, vomiting and sensitivity to light and sound, migraines tend to run in families and are <a href="http://www.mayoclinic.com/health/migraine-headache/DS00120/DSECTION=causes" target="_hplink">triggered by a variety of factors</a>, from foods to stress to environmental changes, according to the Mayo Clinic.

    Treatments can include drugs taken at the onset of an attack and preventive medications -- and a recent, small study suggests that exercise may be just as effective at the latter.

    The findings, published in the journal, <em>Cephalalgia</em>, suggest that <a href="http://www.huffingtonpost.com/2011/10/11/exercise-migraines-prevention_n_1003794.html" target="_hplink">regular physical activity may be able to prevent migraines</a> as well as drugs or relaxation therapy, The Huffington Post reported when the study was released last year.




  • Boosted Immunity


    The brunt of flu season may be behind us, but regular, moderate exercise may help us to stave off a springtime cold by <a href="http://www.msnbc.msn.com/id/10894093/ns/health-cold_and_flu/t/working-out-may-help-prevent-colds-flu/#.T2vztWJAaOF" target="_hplink">upping the body's defenses against viruses and bacteria</a>.

    A sedentary person is likely to catch two to three upper respiratory tract infections each year, <a href="http://www.huffingtonpost.com/2012/01/07/exercise-immunity_n_1190296.html" target="_hplink">HuffPost reported earlier this year</a>, but a moderately active person can cut that number by close to a third.

    But the effect reverses in the case of intense exercise -- marathoners, for instance, may have a <a href="http://www.huffingtonpost.com/2012/01/07/exercise-immunity_n_1190296.html" target="_hplink">two-to-six-fold increase in contracting an upper respiratory tract infection</a> in the weeks following a race.




  • A Sunnier Disposition


    As much as we all sometimes dread the prospect of working out, the truth is that you'll actually <em>feel</em> better after you're done. Physical activity triggers the release of endorphins, those feel-good chemicals that produce a sense of euphoria in the brain. (Who can forget the <a href="http://www.imdb.com/title/tt0250494/quotes" target="_hplink">famous <em>Legally Blonde</em> quote</a>: "Exercise gives you endorphins. Endorphins make you happy. Happy people just don't shoot their husbands, they just don't." Just us?)

    Recent research has further confirmed the link between working out and happiness -- last month, Penn State researchers published findings suggesting that <a href="http://journals.humankinetics.com/jsep-current-issue/jsep-volume-33-issue-6-december/the-dynamic-nature-of-physical-activity-intentions-a-within-person-perspective-on-intention-behavior-coupling" target="_hplink">people who are more physically active</a> reported greater general feelings of excitements and enthusiasm, The Huffington Post reported when the study was published.

    "Our results suggest that not only are there chronic benefits of physical activity, but there are discrete benefits as well," study researcher Amanda Hyde, a kinesiology graduate student at Penn State, <a href="http://www.eurekalert.org/pub_releases/2012-02/ps-pay020812.php" target="_hplink">said in a statement</a>. "Doing more exercise than you typically do can give you a burst of pleasant-activated feelings. So today, if you want a boost, go do some moderate-to-vigorous intensity exercise."




  • More Birthdays


    Could daily workouts be the real fountain of youth? Maybe so.

    A Taiwanese study published last year in The Lancet suggests that even just 15 minutes of physical activity a day can <a href="http://www.huffingtonpost.com/2011/08/16/15-minutes-daily-exercise-live-longer_n_928137.html" target="_hplink">extend life expectancy by three years</a>, compared to people who didn't exercise.