Get physical with cancer prevention
Regular exercise can help reduce risk and ease stress
By Debra Gelbart
As with most things, there is good news and bad news when it comes to risk factors for cancer. The unsettling news is that some cancers may develop or grow in part because a person is overweight or obese. The better news is that being physically active can reduce your risk of getting cancer, regardless of what you weigh.
So, exercise has become a vital part of the medical community’s arsenal against cancer. That message is key for Diljeet Singh, M.D., DrPH, a physician specializing in integrative medicine and cancer prevention at Banner MD Anderson Cancer Center in Gilbert. In addition to improving breathing and muscle function and conditioning the heart, she points out, a couple of other critically important mechanisms are at work when we exercise. We’re telegraphing our endocrine and nervous systems to reduce production of the stress hormones that affect us negatively. At the same time, exercise boosts the hormones and other chemicals that are healthier for the body.
It’s important to keep in mind that excess weight and lack of physical activity may increase levels of insulin and insulin growth factor (IGF). High levels of IGF and its sister, IGF-1, are not good for an adult body. IGF-1, a growth hormone that resembles insulin but differs slightly in its molecular structure, promotes the growth of normal tissue, especially in children, but it also can promote the growth of abnormal tissue (i.e. cancer cells) in adults. Here’s the good news: regular moderate exercise has been shown to reduce the body’s circulating levels of IGF-1.
Researchers know that stress is linked to development of cancer.
“We’re starting to learn the role our sympathetic nervous system might play in the growth of cancer,” Singh says. In a busy, tension-filled world, she explained, “a nearly constant ‘fight or flight’ response to stress increases production of a number of what we call ‘stress modifiers.’” These include the steroid hormone cortisol, which increases blood sugar and suppresses the immune system; adrenaline, a hormone that increases heart rate and blood pressure; and norepinephrine, similar to adrenaline. If these hormones are always in overdrive, Singh says, they can fuel the growth of abnormal or mutated cells, the precursors to cancer.
“Physical activity seems to modify the activity of these stress chemicals,” she says, and instead, it increases production of endorphins, the body’s “feel-good” chemicals.
Exercise can help you manage not only your stress, but your body weight as well. “Exercise also helps you sleep better,” Singh says, “and greater muscle mass makes you crave more protein and other healthy foods.” In addition, she said, people who exercise often stay better hydrated.
Just 30 minutes a day
What is often intimidating about exercise is the mistaken belief that you have to do a lot of it to enjoy the benefits. “All you need is about 150 minutes of moderate-intensity activity every week,” Singh says, emphasizing that 150 minutes translates into 30 minutes five times a week. “Thirty minutes of exercise a day can really help with stress management.”
Best of all, you don’t need fancy equipment or a gym membership to exercise. “All you need to do is walk,” Singh says. An optimal workout would be walking “for up to 10 minutes at a time fast enough that you would have trouble chatting,” she says. After 10 minutes or so, slow down and walk at a more moderate pace for about five minutes. Then, repeat the cycle. “But even walking at a moderate pace for 30 minutes can be very beneficial.”