Defining fit: Duke professor helps set new federal definition of an active lifestyle

Under new federal guidelines, less than one-third of adults and one-fifth of children in America will be considered physically active. 

William Kraus, Richard and Pat Johnson university professor of medicine, served on the Physical Activity Guidelines Advisory Committee responsible for updating past physical activity advisories by the Department of Health and Human Services. This second edition of the Physical Activity Guidelines made changes to the original standards released in 2008, including focusing less on 10-minute blocks of physical activity and more on tackling many Americans’ sedentary lifestyles.

“It’s all about less sitting and more moving,” Kraus said.

The new guidelines call for adults to get at least 150 minutes of moderate-intensity aerobic exercise—including brisk walking, running or bicycling—each week, as well as two sessions of muscle strengthening, which can include weight lifting or resistance training 

Children younger than 6 years old were included for the first time in the new guidelines.

The new policy mandates that preschool-aged children should be physically active throughout the day to enhance growth and development. 

For school-aged children and adolescents, the committee recommended at least one hour of moderate-intensity aerobic activity each day and three sessions of muscle strengthening each week for children. 

The guidelines emphasized instilling healthy habits in children.

Kraus said the changes to the original guidelines aimed to “decrease the amount of time during the day we spend sitting at a desk” and recognize the health benefits of small physical activities throughout the day.

He also warned against the “soft science” of requiring 10-minute intervals of exercise. Any amount of exercise is better than nothing, he said.

Kraus offered his advice on how the University could adhere to the new guidelines and make its students, faculty and administrators healthier. 

He called lecture classes, where students sit for long times, extremely unhealthy and urged professors “to find ways to get their students moving”—whether by holding classes outdoors, or letting students stand up and move around during class.

Though Duke undergraduates get more exercise than average college students, Kraus said that he hoped Duke would improve its physical activity levels and become a model for greater national change. 

While students stay fit during their time at Duke, he said that exercise problems for Duke students often develop after graduation.

“I’m most worried for tech and finance students who will soon be working in New York City in 18-hour shifts,” Kraus said.

Though maintaining exercise right after college can be difficult, Kraus stressed the importance of developing and maintaining consistent exercise habits as their careers move forward. 


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