Preventive Medicine Column

Dr. David L. Katz

A recent study in JAMA shows that just 20 minutes of daily physical activity is enough to be the difference between the onset of diabetes or dodging that bullet in at-risk children.

The researchers randomly assigned over 200 overweight or obese grade school students to 20 or 40 minutes of supervised aerobic activity 5 days a week, or to a control group in which habitual activity (or lack thereof) was maintained, for a period of 13 weeks.

Both doses of physical activity significantly improved insulin sensitivity, suggesting diabetes prevention over time. The higher dose of activity was more effective than the lower at reducing weight and body fat, but both were significantly better than control.  And in the case of fitness, measured formally with peak oxygen consumption, both doses were comparably effective, and both much better than control, i.e., doing just about nothing.

So while more exercise is better, some- and a rather small ‘sum’ at that- can do a remarkable amount of good.  If we know- and it seems we do- that fitting 20 minutes of activity in during every school day can be enough to prevent diabetes in a large and growing percentage of our kids, it’s hard to believe we would fail to act on that knowledge.

That much more so when we consider that a daily dose of exercise is likely to enhance academic performance, rather than interfere with it.  ‘Sound mind, sound body’ should sound familiar, because it’s the kind of sensible advice our grandparents gave us.  Science now points in the same direction, it just took longer to get there.

Getting to 20 minutes a day is not a big hill to climb.  My colleagues and I can provide a boost up with a program called ABC for Fitness, freely available to all courtesy of my non-profit, Turn the Tide Foundation.  Designed for just this purpose- to give all kids enough daily physical activity to immunize them against serious chronic diseases- ABC for Fitness reconciles the square peg of physical education to the round hole of the modern school day, by breaking physical activity up into brief bursts throughout the day, doled out right in the classroom.  By teaching during the bursts, teaching time can actually be increased.

We studied the program in over 1,000 children, half receiving ABC for Fitness, the other half a standard curriculum.  The daily activity bursts were associated with improved fitness, decreased behavioral problems, preserved academic performance, reduced medication use for asthma, and a 33% reduction in overall prescriptions for ADHD.  Recess is a far better remedy for the rambunctiousness of young children than Ritalin!

We have reason to think benefits are similar for adults.  We know, for instance, from the Diabetes Prevention Program that modest improvements in weight, activity, and diet can prevent diabetes almost two times in three among high-risk adults.

We know as well from the largest available database on sustained weight loss, the National Weight Control Registry, that even modest daily activity appears to be a nearly universal element in successfully maintaining weight over the long term.  Doing so, in turn, insulates against all of the major chronic diseases for which obesity is a risk factor, including, but not limited to: heart disease, cancer, stroke, and diabetes.

With that in mind, my colleagues and I have a free program to offer adults, to help fit some or all of those minutes in each day: ABE for Fitness.

There are 1440 minutes in every day.  Of that total, 20 minutes represents less than 1.4%.   If a day were a dollar, for a penny and half of it you could pay to keep diabetes away from you, and your children.

Better still, we might commit in the might of our multitudes- as loving parents, grandparents, aunts, and uncles- to insisting that every school in the country offer every young child the minimal, healthful dose of physical activity.  We know how valuable it is, and we know it can be done while promoting rather than hindering academic achievement.  And it can be done at no cost.  Why should we accept any excuses?

All this is a matter of mere minutes a day, minutes that can be the difference between diabetes and staying healthy.  That is clearly a difference that matters.   We all have the same invitation, even if each of us chooses to march to the beat of a different drummer: to make a small investment of our daily time for a big return in health, for our children and ourselves alike.




Dr. David L. Katz;