By Dr. Mercola
Compelling evidence suggests exercise can not only help slash your risk of cancer, it also helps cancer patients recuperate faster, and diminishes your risk of cancer recurrence.
There’s also plenty of research demonstrating that exercise benefits your brain as much as it does your body, and with rates of dementia rising precipitously, this is another significant reason to make sure you stay more active, regardless of your age.
Middle-Age Fitness Cuts Men’s Cancer Risk
One of the benefits of exercise is that it decreases your insulin resistance, and this is a profoundly effective strategy to reduce your cancer risk. This creates a low sugar environment that discourages the growth and spread of cancer cells.
Exercise also improves circulation, driving more oxygen into your tissues, and circulating immune cells in your blood. Previous animal research1,2 suggests regular exercise may be the key to significantly reduce your chances of developing liver cancer, which is among the most common types of cancer.
More recently, research3,4 published in the journal JAMA Oncology found that being fit in middle age cut men’s risk of being diagnosed with lung cancer by 55 percent, and bowel cancer by 44 percent.
High levels of cardiorespiratory fitness (CRF) in middle age also helped men survive cancer, reducing their risk of dying from lung, bowel, and prostate cancer by nearly one-third (32 percent). Not surprisingly, it also reduced their risk of dying from cardiovascular disease by 68 percent.
Other Studies Show 20-40 Percent Reduced Cancer Risk with Regular Exercise
Earlier research has also found that exercise—in this case weight training—cut men’s risk of dying from cancer by 40 percent. Similar findings have been reported in other studies.
According to a 2003 paper5 published in the journal Medicine & Science in Sports & Exercise, "more than a hundred epidemiologic studies on the role of physical activity and cancer prevention have been published." The authors noted that:
"The data are clear in showing that physically active men and women have about a 30-40 percent reduction in the risk of developing colon cancer, compared with inactive persons…
With regard to breast cancer, there is reasonably clear evidence that physically active women have about a 20-30 percent reduction in risk, compared with inactive women.
It also appears that 30-60 min·d-1 of moderate- to vigorous-intensity physical activity is needed to decrease the risk of breast cancer, and that there is likely a dose-response relation."
Exercise Boosts Effectiveness of Breast Cancer Treatment
Another recent study6 reported in the New York Times7 found that aerobic exercise slowed the growth of breast cancer tumors in mice. By increasing tissue oxygenation, it also improved the effectiveness of chemotherapy. As noted in the article:
“The results raise the possibility that exercise may change the biology of some malignant tumors, potentially making them easier to treat.”
In one part of the trial, mice with breast cancer were divided into four groups. One group received no treatment and remained sedentary; one group ran on wheels but received no drug treatment; a third group received chemotherapy treatment while remaining sedentary; and the fourth group received both chemotherapy and exercise.
At the end of the trial, the sedentary mice had large, hypoxic tumors. Hypoxia is a condition in which your body, or a region of your body, is deprived of oxygen, which is known to make tumors less responsive to chemotherapy.
The exercise- and chemotherapy-only groups both revealed a slow-down in tumor growth, compared to the sedentary, untreated mice. The group that fared the best, however, was those who exercised in combination with chemotherapy treatment. As noted in the article:
“That result suggests, Dr. Dewhirst says, that exercise had made the breast cancer tumors in the mice more amenable to the chemotherapy. By making the tumors less hypoxic — and paradoxically healthier, he says — exercise ‘also had made those tumors easier to kill.’
At the same time, exercise seems to have fought the tumors independently of the chemotherapy drugs. In the animals that ran but did not receive chemotherapy, Dr. Dewhirst says, the scientists found blood markers indicating a high degree of tumor cell death...”
Exercise Needs to Be Part of the New Standard of Care for Cancer
Mounting research suggests that exercise is a really important part of cancer care and prevention, and Macmillan Cancer Support8 has made strong arguments for its inclusion in standard cancer care. I personally believe it is negligent malpractice to not seek to include it nearly everyone’s cancer plan.
The British organization recommends that all patients getting cancer treatment should be told to engage in moderate-intensity exercise for two and a half hours every week, stating that the advice to rest and take it easy after treatment is an outdated view.
Macmillan offers loads of helpful information about the benefits of exercise for cancer patients on their website, and also has a number of videos on the subject, available on their YouTube channel.9 According to Ciaran Devane, chief executive of Macmillan Cancer Support:10
"Cancer patients would be shocked if they knew just how much of a benefit physical activity could have on their recovery and long term health, in some cases reducing their chances of having to go through the grueling ordeal of treatment all over again..."
Indeed, the reduction in risk for recurrence is quite impressive. For example, previous research has shown that breast and colon cancer patients who exercise regularly have half the recurrence rate than non-exercisers.11 Macmillan Cancer Support also notes that exercise can help you to mitigate some of the common side effects of conventional cancer treatment, including:
Reduce fatigue and improve your energy levels Manage stress, anxiety, low mood, or depression Improve bone health Improve heart health (some chemotherapy drugs and radiotherapy can cause heart problems later in life) Build muscle strength, relieve pain, and improve range of movement Maintain a healthy weight Sleep better Improve your appetite Prevent constipation
A Fit and Healthy Lifestyle Also Improves Cognitive Function in Seniors
According to a recent randomized controlled trial,12,13 in seniors who are at high risk of dementia, cognitive decline can be reduced with a comprehensive program addressing diet, exercise, brain training, and managing metabolic and vascular risk factors. A total of 1,260 adults in Finland, aged 60-77 years, participated in the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability. Half were randomly assigned to the intervention group, while the other half served as controls.
All participants were at high risk of dementia. The intervention consisted of attending regular meetings over the two-year trial period with various health professionals to address diet, exercise, brain training exercises, and metabolic risk factors. At the end of two years, the intervention group scored 25 percent higher overall on the Neuropsychological Test Battery (NTB)—a standard test to evaluate mental functioning—than the control group. They scored even higher on certain parts of the test.
As reported by Science Daily:14
“[F]or executive functioning (the brain's ability to organize and regulate thought processes) scores were 83 percent higher in the intervention group, and processing speed was 150 percent higher. According to Professor Kivipelto, ‘Much previous research has shown that there are links between cognitive decline in older people and factors such as diet, heart health, and fitness. However, our study is the first large randomized controlled trial to show that an intensive program aimed at addressing these risk factors might be able to prevent cognitive decline in elderly people who are at risk of dementia.’"
Other Research Shows Exercise Boosts Brain Growth and Regeneration
Scientists have been linking physical exercise to brain health for many years. In fact, compelling evidence shows that physical exercise helps build a brain that resists shrinkage and increases cognitive abilities.15 For example, we now know that exercise promotes a process known as neurogenesis, i.e. your brain’s ability to adapt and grow new brain cells, regardless of your age. According to John J. Ratey, a psychiatrist who wrote the book Spark: The Revolutionary New Science of Exercise and the Brain, there’s overwhelming evidence that exercise produces large cognitive gains and helps fight dementia.
One of the mechanisms by which your brain benefits from physical exercise is via a protein called Brain Derived Neurotrophic Factor (BDNF). Exercise initially stimulates the production of a protein called FNDC5, which in turn triggers the production of BDNF. BDNF is a remarkable rejuvenator in several respects. In your brain, BDNF not only preserves existing brain cells,16 it also activates brain stem cells to convert into new neurons, and effectively makes your brain grow.
Research17 confirming this includes a study by Kirk Erickson, PhD, in which seniors aged 60 to 80 who walked 30 to 45 minutes, three days per week for one year, increased the volume of their hippocampus by two percent. The hippocampus is a region of your brain important for memory. Erickson also found that higher fitness levels were associated with a larger prefrontal cortex. He called exercise as "one of the most promising nonpharmaceutical treatments to improve brain health." Two additional mechanisms by which exercise protects and boosts your brain health include the following:
- Reducing plaque formation: By altering the way damaging proteins reside inside your brain, exercise may help slow the development of Alzheimer's disease. In one animal study,18 significantly fewer damaging plaques and fewer bits of beta-amyloid peptides, associated with Alzheimer's, were found in mice that exercised.
- Decreasing BMP and boosting Noggin: Bone-morphogenetic protein (BMP) slows down the creation of new neurons, thereby reducing neurogenesis. If you have high levels of BMP, your brain grows slower and less nimble. Exercise reduces the impact of BMP, so that your adult stem cells can continue performing their vital functions of keeping your brain agile.
In an animal research,19,20 mice with access to running wheels reduced the BMP in their brains by half in just one week. In addition, they also had a notable increase in another brain protein called Noggin, which acts as a BMP antagonist. So, exercise not only reduces the detrimental effects of BMP, it simultaneously boosts the more beneficial Noggin as well. This complex interplay between BMP and Noggin appears to be yet another powerful factor that helps ensure the proliferation and youthfulness of your neurons.
Exercise—an Important Component of Cancer and Dementia Prevention
There’s no denying that exercise can have a profound impact on your health, and a major part of its benefit lies in its ability to prevent disease. Dementia and cancer are but two in an inordinately long list of health problems that can arise as a result of chronic inactivity. Your metabolic and cardiovascular health is also largely dependent on exercise. In fact, one of the primary benefits of exercise is that it improves your insulin and leptin sensitivity, and insulin/leptin resistance is a hallmark of most chronic diseases, including cancer.
Ideally, you’ll want to establish a comprehensive exercise program that includes high-intensity exercises and strength training—both of which have been shown to be of particular benefit for brain health and cancer prevention. I also urge you to consider walking more, in addition to your regular workout regimen. Ideally, aim for 7,000 to 10,000 steps per day. Also avoid sitting as much as possible—ideally limiting your sitting to three hours a day or less. Naturally, if you have cancer or any other chronic disease, you will need to tailor your exercise routine to your individual circumstances, taking into account your fitness level and current health.
Often, you will be able to take part in a regular exercise program -- one that involves a variety of exercises like strength training, core-building, stretching, aerobic, and anaerobic -- with very little changes necessary. However, at times you may find you need to exercise at a lower intensity, or for shorter durations. Always listen to your body and if you feel you need a break, take time to rest. But even exercising for just a few minutes a day is better than not exercising at all, and you'll likely find that your stamina increases and you're able to complete more challenging workouts.
If your immune system is severely compromised, you may want to exercise at home instead of visiting a public gym. But remember that exercise will ultimately help to boost your immune system, so it's very important to continue with your program even if you suffer from chronic illness or cancer.