Ask the Expert: How does exercise contribute to cancer prevention?
Q: How does exercise contribute to cancer prevention?
A: There’s evidence that physical activity can help reduce the risk of several types of cancer, with the evidence usually being stronger in cases of breast, colon or colorectal cancers. There is, however, also evidence for prostate cancer, and perhaps even lung cancer, and there is growing evidence for some of the other cancers that are not as well researched. In general, evidence shows that people who are more physically active may see a greater reduction in developing cancer than those who are sedentary. We’ve seen studies that show a 15 to 25 percent reduction in developing cancer, just from exercise alone. For colorectal cancer, I’ve seen studies showing numbers as high as a 27 percent reduction.
Q: Why does exercise appear to help?
A: While we don’t know the definite reason exercise seems to help prevent cancer, some theories relate to hormones and how physical activity helps regulate them. In an active person, hormone levels tend to be more properly regulated, even when sitting at rest, as compared with someone who is sedentary. Physical activity has been shown to keep hormone levels of estrogen, insulin and growth factor hormone at more normal levels, or in a state of homeostasis, which means your body is in state of balance.
Q: Does exercise help with stress management, too?
A: I think the biggest way exercise relates to stress management has to do with how people might choose unhealthy options as a way of coping with stress. Smoking and compulsive eating, for example, can contribute to, or be linked with, certain types of cancers. We find physical activity is a better outlet for dealing with stress, as it reduces the likelihood you’ll overeat or smoke in response to stress.
Q: What kind of exercise do you suggest?
A: You can choose something as simple as walking. You want to walk at a moderate, brisk pace, though, not just stop-and-go walking with your dog. I also suggest using a pool, especially when it gets warmer. The pool’s especially good for people who have joint issues; they’re usually able to do low-impact exercises and aerobics and the buoyancy of the water makes it easier on their joints. You could also choose hiking or biking, and I’ve even suggested Zumba classes. Sometimes, the biggest motivator is finding something you enjoy doing. Then it’s something you look forward to.
Q: How frequently do I need to work out?
A: We always recommend a minimum of 150 minutes of activity per week. Most people break that into 30 minutes a day for five days a week. But if you’re sedentary and have other conditions such as high blood pressure or diabetes, try starting with 15 minutes at a time and work toward that 30-minute goal to accumulate that 150 minutes per week.
Q: How do I get started?
A: Start slowly. That 150 minutes is the number we look toward, but that can be a lofty goal in the beginning, especially for someone who’s been sedentary, so start slowly and work toward the goal. If you have any current health concerns, especially a pre-existing heart condition or a joint-related condition, you should speak first with your physician before starting an exercise regimen. If you want to see a significant change in how your body looks and feels, give it about two months. There’s always the potential to see a difference in as little as two weeks, but the body does take it time when making these changes. If you’re consistent and you give it about two months, there’s a very good chance you’ll see a difference in how you look and feel.
Josh Wludyga is an exercise physiologist with Banner MD Anderson Cancer Center.