Most people give up before they begin to reap rewards offered by regular exercise

Mark this date on your calendar: March 7.Thats when New Years resolutions might stick for good, according to one study that estimates it takes an average of 66 days to develop a new habit.But most people give up sooner than that, with 80% abandoning their pledges by mid-February, according to Gallup.Thats especially unfortunate since traditionally, the most common vow is to exercise more, a resolution that could improve health, reduce risk of chronic disease and save money.
Inadequate levels of physical activity are associated with $117 billion in annual health-care costs, according to the U.S. Centers for Disease Control and Prevention, and contribute to one in 10 premature deaths.
To help avoid those consequences, the Department of Health and Human Services advises adults to move more and sit less.
According to its latest guidelines, published in 2018, any amount of moderate-to-vigorous physical activity is helpful.
But for substantial benefits, adults are advised to get 150 to 300 minutes of moderate-intensity aerobic activity each week or 75 to 100 minutes of vigorous aerobic activity, plus twice-weekly muscle-strengthening exercises of moderate or greater intensity involving all major muscle groups.
Start now, and the benefits could begin accruing by Valentines Day.
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In six weeks, you could notice a change in blood pressure independent of weight loss, said Libby Richards, an associate professor at the Purdue University School of Nursing. You could tone up and have better blood-sugar control. Youll likely sleep better, and you may have a better mood.
But people usually give up before the benefits kick in, she said, or they dont get as much exercise as they claim.
If you ask people if theyre meeting the physical-activity guidelines, theyre like, I sure am, Dr. Richards said. But there is a difference when you ask them and when you actually measure them.
In 2018, the most recent year available, 53.3% of U.S. adults surveyed by the CDC said they met physical-activity guidelines based on the recommended minutes of moderate or vigorous exercise. When asked about getting two-plus days of muscle-strength training, only 23.2% said they met the guidelines.
Thats not great, Dr. Richards said. Its less than a quarter, and you must keep in mind that its self-reported data. The reality is that its lower than that.
Researchers examined a nationally representative sample of 6,525 adults who wore accelerometers to track their movements and found that 44.8% met the physical-activity guidelines for aerobic activity, or 8.5 percentage points lower than the self-reported figure.
But when the researchers counted lifestyle activities like vacuuming, gardening and leisurely walks as contributions toward the goal of 150 minutes of exertion, 95% of participants met the guidelines.
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Its literally the closest thing we have to a fountain of youth.
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Libby Richards, associate professor at Purdue University School of Nursing, on regular exercise
The study, a collaboration of researchers at California State University, University of North Carolina, University of Missouri at Kansas City and Childrens Mercy Hospital in Kansas City, Mo., was published in the peer-reviewed journal Frontiers in Public Health in 2019.
The researchers didnt assess the muscle-strengthening guidelines, and with aerobic activity, they found demographic differences: Men were consistently more active than women. People of normal weight tended to be more active than people who were overweight. Hispanics were more active than non-Hispanics. And activity decreased with age.
The National Cancer Institute estimates that with high levels of physical activity, the risk of bladder cancer decreases by 15%; breast cancer by 12% to 21%; colon cancer by 19%; endometrial cancer by 20%; esophageal cancer by 21%; kidney cancer by 12%; and stomach cancer by 19%. Researchers believe the reductions occur because exercise decreases inflammation, helps prevent obesity and improves immune-system functioning.
According to the Frontiers in Public Health study, activities at different levels of intensity also contribute to improved health.
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In the past, we ignored activity if it was not at a moderately intense level, like brisk walking, but light-intensity activity has a lot of health benefits, Dr. Richards said, particularly for people who are sedentary. The more active and in shape you are, the more you have to do to see health gains. But people who are pretty inactive, they dont have to do much to start getting physical health benefits.
And that might make it a little easier to resolve to be more active in 2021.
Its literally the closest thing we have to a fountain of youth, Dr. Richards said. If you can keep it up, the health benefits are tremendous.
Write to Jo Craven McGinty at Jo.McGinty@wsj.com
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