November 4, 2011
Inactivity Increases Risk Of Cancer
The analysis of a new major study has concurred with decades of research that being active means being healthy, and also reduces the risk of cancer.
But just being active doesn´t mean you are fit for life. The new evidence suggests that people who have sedentary lifestyles, even when they do have exercise routines, are at an increased risk of cancer.
The study, published in the journal Cancer Prevention Research and presented at the American Institute for Cancer Research (AICR) annual conference in Washington, DC, has revealed a strong connection between inactivity and cancerous cell growth. Around 92,000 cases of breast and colon cancer each year can be attributed to lack of exercise, and researchers are now urging people to get and stay fit, adding in a few minutes of physical activity for every hour they spend being inactive.
“This gives us some idea of the cancers we could prevent by getting people to be more active,” 'ead study author epidemiologist Christine Friedenreich of Alberta Health Services in Calgary, Canada, told USA Today. “This is a conservative estimate. The more physical activity you do, the lower your risk of these cancers,” she said.
The numbers “seem like very reasonable estimates,” added Alpa Patel, an American Cancer Society epidemiologist who studied the data.
One study of post-menopausal women confirmed that taking brisk daily walks helps to reduce several key biological indicators of cancer risk, including sex hormone levels, insulin resistance, inflammation and body fatness.
“In breast and colon cancers, for example, we´re seeing overall risk reductions of about 25 to 30 percent associated with higher levels of physical activity,” Friedenreich said. Experts have known for years that physical activity decreases the risk of chronic disease, but Friedenreich said the new data gives estimates on the number of cases that could be prevented if people were more physically active.
“A brisk daily walk of at least 30 minutes could lower a person's risk over time for breast cancer and colon cancer,” Alice Bender, a registered dietitian with AICR, told USA Today.
Friedenreich reviewed more than 200 cancer studies from around the world and found convincing evidence that physical activity on a regular basis reduces the risk of breast cancer, colon cancer and endometrial cancer by 25 to 30 percent. And there is some evidence that it also reduces the risk of lung, prostate and ovarian cancer as well, Friedenreich said.
Patel has also investigated the health risks of sitting too long without moving around, which is known as “sitting disease.”
In that study, Patel and colleagues looked at 123,000 people and found that the more people sat around, the higher their risk of dying early was. “Even among individuals who were regularly active, the risk of dying prematurely was higher among those who spent more time sitting,” she said.
Even if you do 30 minutes of exercise a day, you need to make sure you are not just sitting around the rest of the day, said Patel. “You have to get up and take breaks from sitting.”
James Levine, a professor of medicine at Mayo Clinic in Rochester, Minnesota, said many people sit an average of seven to 9 and a half hours a day. “If you´ve sat for an hour, you´ve probably sat too long,” he told USA Today.
Another study highlighted that even those who are physically active but sit for long periods are at greater risk of developing cancers. Researchers from Australia´s Baker IDI Heart and Diabetes Institute discovered that that even breaks as short as one minute can help prevent health complications.
“Sitting time is emerging as a strong candidate for being a cancer risk factor in its own right,“ said Neville Owen, who presented evidence at the Washington conference. “It seems highly likely that the longer you sit, the higher your risk. This phenomenon isn't dependent on body weight or how much exercise people do.”
His study revealed that the majority of adults´ days are spent being inactive.
The study found that on average, 60 percent (9.3 hours) of a person´s waking day was spent sedentary. This includes mealtimes, commutes to and from work, computer and TV time. Another 35 percent (6.5 hours) was spent in light activity such as walking to a meeting.
Office workers on average spend up to 75 percent of their workday sitting, with about 30 minutes of light activity during that time.
“When you´re sitting, the big muscles, especially in lower part of body, are completely unloaded. They´re not doing their job,” Owen said. That inactivity prompts changes in the body´s metabolism, Owen said, and produces a number of biological signals, what scientists call biomarkers, which are linked to cancer.
“It´s been surprisingly consistent with what strong relationships there are between physical inactivity and these biomarkers of cancer risk,” Owen said.
Owen is hopeful that the findings will prompt practical recommendations on workplace health, such as removing office waste baskets, using standing desks, and meetings with standing breaks.
“Taken together, this research suggests that every day, we´re each given numerous opportunities to be active and protect ourselves from cancer, not one,” AICR spokesperson Alice Bender added. “We need to start thinking in terms of make time and break time.”
For the most part, cancer researchers have emphasized the importance of getting a certain amount of dedicated exercise to lower risk of disease, and experts say it is still a good idea to follow those guidelines.
The US Centers for Disease Control and Prevention recommends adults should get 150 minutes of moderate-intensity exercise or 75 minutes of vigorous exercise each week, along with weekly muscle-strengthening activities.
But now it seems that the health benefits of being active require more than a regular dosage of daily exercise.
“It´s scary to think that even if I am going to the gym 30 to 45 minutes every day, that might not be enough,” said Patel. “But the other important message here is for the two thirds of U.S. adults who don´t engage in regular physical activity, there´s benefit in just moving around.”
Joan Vernikos, the former director of life sciences at the National Aeronautics and Space Administration (NASA) and author of “Sitting Kills, Moving Heals,” said simply standing once every 30 minutes can help stimulate the body by fighting the forces of gravity.
“It´s not how long you stay standing, but how often you stand up, how often you challenge your body to respond,” Vernikos told ABC News. “What provides the baseline of physiological activity in the body is small to large movement, intermittently all day, every day.”
On the Net:
- Cancer Prevention Research
- American Institute for Cancer Research
- Alberta Health Services
- American Cancer Society
- Mayo Clinic
- Baker IDI Heart and Diabetes Institute