Get Off Your Duff and Get Moving!

There are a few articles hitting the news lately about how too much sitting contributes to a number of cancers. The reason for this spate of news is a talk given by Charles Matthews of the National Cancer Institute (NCI) at the annual American Association for the Advancement of Science (AAAS) meeting held in Austin, TX in February 2018, "Unraveling the Relations Between Sedentary Behavior, Physical Activity and Health." Matthews is in the process of helping rewrite the NCI's 10-year-old exercise guidelines, based in part on what large epidemiologic studies using accelerometers are showing with regard to what constitutes beneficial exercise. (For anyone like me who doesn't know what epidemiologic studies are - they are "studies of how often diseases occur in different groups of people and why."1)

Sedentary lifestyles and cancer risk

According to Mia De Graaf, Health Editor for, Dr. Matthews told the audience that his research indicates that there are a number of cancers, including breast, colon, lung, and head or neck, linked to sitting too much. In fact, De Graaf reports that Matthews said that "just one hour of TV a day puts even the most active of us at higher risk" for at least nine kinds of cancer.2 Wow!

Current exercise guidelines, published in 2008, recommend:

  • Avoid inactivity. Some exercise is better than none.
  • Substantial health benefits are gained when adults do at least 150 minutes a week of moderate-intensity or 75 minutes a week of vigorous-intensity aerobic physical activity
  • More extensive health benefits are realized when adults do at least 300 minutes of moderate intensity or 150 minutes a week of vigorous-intensity aerobic physical activity
  • Adults should do moderate to high-intensity muscle-strengthening activities for all major muscle groups on two or more days a week.3

However, the NCI now believes that we actually need around four to five times the recommended minimums.

How much should we be exercising?

Dr. Matthews and the NCI has been investigating not only how much activity we need, but what the point of diminishing returns is. Researchers have found that 25 minutes a week of moderate to high-intensity exercise per week gives about the same benefit as up to 74 minutes of the same. Additional benefits are accrued at 75 minutes or more a week of strenuous activity. I'm not sure how many people have the time to put in 75+ minutes of strenuous activity! I'll probably be striving to reach the 25-minute mark.

Unfortunately, Dr. Matthews' research showed that sitting for just one hour watching TV puts even those who get their recommended exercise at higher risk for sedentary-related health issues. Well, OK then. What the heck are we supposed to do? Throw away our televisions altogether?

No. "Most people are sedentary  60 percent of the day. But that still leaves you four, five, six hours a day to be active," Matthews is quoted as telling conference attendees.2

Will guidelines actually impact behavior?

I don't know about you, but I am really curious to see what the updated exercise guidelines are going to look like. I suspect that a majority of Americans do not regularly meet current guidelines. My opinion is that publishing even more stringent guidelines is not likely to result in much-changed behavior.

What do you think? Do you meet current exercise guidelines? Will you be able to get 25 minutes of moderate to strenuous activity accomplished every week?

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