Americans seeking to stay healthy can get their exercise in small increments of just a few minutes at a time, according to new guidelines issued by the government Monday that again encourage a largely sedentary nation to start moving.

The guidance from a committee appointed by the Department of Health and Human Services does away with the official government position that physical activity should occur in sessions of at least 10 minutes.

The earlier position was contained in the government's first physical activity guidelines, issued in 2008.

The document released Monday at the American Heart Association's 2018 Scientific Sessions is the first update since then. It was published in the Journal of the American Medical Association.

"Current evidence shows that the total volume of moderate-to-vigorous physical activity is related to many health benefits; bouts of a prescribed duration are not essential," the committee of health experts wrote.

"Sit less, move more. Whatever you do, it really all counts," Brett P. Giroir, assistant secretary for health at HHS, said in an interview.

Thomas Allison, director of sports and exercise cardiology at the Mayo Clinic in Rochester, Minnesota, said short bouts of exercise are valuable to break up long stretches of sitting.

But research shows that multiple short sessions should involve similar energy expenditure to have the same impact as one longer session, or additional time moving will be needed, he said.

Allison endorsed the overall intent of the new recommendations, which encourage movement of any kind, for any duration, in a country where about 80 percent of the population is not getting the minimum amount of recommended physical activity.

He suggested that deskbound workers and other sedentary people get up and move about two minutes every half-hour.

The government's concern over American fitness is not new. President Teddy Roosevelt challenged Marines in 1908 to show that they could march 50 miles (80 km) in 20 hours, and President-elect John F. Kennedy voiced his concerns about a nation going soft in an article he wrote for Sports Illustrated magazine in 1960.

For adults to stay healthy, the new guidelines call for 150 to 300 minutes of moderate-intensity exercise or 75 to 150 minutes of vigorous-intensity physical activity each week, along with at least two days a week of muscle-strengthening exercises.

Those recommendations are unchanged from a decade ago.

The guidelines cite walking briskly at 2.5 to 4 miles (3.9 to 6.4 kilometres) per hour, playing volleyball or raking leaves as moderate-intensity activity.

Vigorous-intensity exercise includes jogging or running, carrying heavy groceries or taking a strenuous fitness class, the panel said.

Some workouts, such as swimming and cycling, can fall into either category, depending on the effort expended.

Children and teens ages 6 to 17 should get 60 minutes of vigorous activity every day, plus three days a week of activity that strengthens muscles, according to the recommendations.

Older adults should do exercise to improve balance as well as cardio and muscle-strengthening workouts, the panel said.

For the first time, the guidelines include a recommendation for preschoolers, noting that children ages 3 to 5 "should be physically active throughout the day to enhance growth and development."

The document also contains specific advice for pregnant and postpartum women and people with disabilities.

The panel noted that in the decade since the first guidelines were issued, research has expanded the recognized benefits of movement.

These include reducing the risk of cancer, anxiety and depression; improving cognitive function and sleep; aiding bone health and regulating weight gain in preschoolers; protecting against weight gain, gestational diabetes and postpartum depression in pregnant women and new mothers; and decreasing the risk of falls among older people.

Even a single workout can have some impact in some areas, the committee noted.

Researchers have also learned more in recent years about how damaging a sedentary lifestyle can be. The report notes that "an estimated US$117 billion in annual health care costs and about 10 percent of premature mortality are associated with inadequate physical activity."

"Being physically active," the guidelines state, "is one of the most important actions individuals of all ages can engage in to improve their health."

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This article was originally published by The Washington Post.