A recent study offered some encouraging potential ammunition in the fight against rising childhood obesity rates: As little as 20 minutes of daily, vigorous physical activity can reduce diabetes risk and increase fitness.
In the study led by Catherine Davis, PhD, a professor of pediatrics at the Medical College of Georgia and researcher with the Institute of Public and Preventive Health at Georgia Health Sciences University, kids ages 7–11 participated in either 20- or 40-minute exercise sessions or maintained their sedentary lifestyles. The majority of the study participants were obese at the beginning of the study.
When compared to kids who did not exercise, children who exercised for 40 minutes daily had a 22 percent reduction in insulin resistance, and those who exercised for 20 minutes had an 18 percent reduction. Insulin resistance is a risk factor for diabetes, and a rise among children diagnosed with type 2 diabetes, formerly termed “adult diabetes,” is a major public health concern.
“Basically, the advantage of the 40-minute group was in reduced fatness, but the 20-minute group was apparently effective in reducing diabetes risk and improving aerobic fitness,” Davis told The Nation’s Health. “So 20 minutes of vigorous activity could go a long way in improving children’s health, and that could be done during the school day.”
The exercise sessions included running and tag games and modified sports, unlike some typical team sports that have kids “standing there waiting their turn,” Davis said. And also unlike many school physical education classes, the staff to student ratio was one to nine.
“We weren’t trying to produce little athletes,” Davis said. “We were trying to make sure the kids were engaged and having a good time and getting their heart rates up.”
Participants wore heart-rate monitors and were rewarded with small toys for keeping their heart rates high.
“Instead of criticizing them for being slow or not trying, we reward them for getting their heart rate up, and that improves their fitness, and later, they can go faster,” Davis said. “I think that’s a key lesson. It’s so easy to criticize a child for not making an effort because they’re moving slower than their peers. An unfit child is not going to be able to move that fast, but they may be doing all they can.”
Children in both the 20- and 40-minute exercise group lost body fat and improved aerobic fitness without changing their diets. Researchers offered the exercise sessions five days a week, and results were equal for girls and boys. While the study found a benefit from 20–40 minutes of daily vigorous activity, that likely translates into one half hour to an hour of daily exercise in “real-world” settings outside of a research gym, Davis said.
Davis said she was surprised at the nearly equal reduction in diabetes risk among those children who exercised in 20-minute and 40-minute sessions.
“I was so excited about the idea of using exercise to reduce diabetes risk,” Davis said. “When kids started coming down with Type 2, I thought, this is just wrong.”
Davis said she hopes the study results will help in the design of public health interventions sorely needed in light of the fact that a third of American school children are overweight.
“My vision is that parents everywhere will demand from their school system that there is adequate physical activity, that children are encouraged instead of being discouraged about athletics if they’re not the fastest kids and that school property will be available for physical activity programs,” Davis said. “This could be gym class if it were active, it could be physical activity as part of classroom lessons, which has been shown by a couple of research groups to be effective not only in activating the kids but in improving their performance in academics.”
The study was published in the Sept. 19 Journal of the American Medical Association and is online at jama.jamanetwork.com/article.aspx?articleid=1360862.
- Copyright The Nation’s Health, American Public Health Association
