New Answers on Exercise

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The first session I attended at last month’s ADA Scientific Sessions featured three experts on the effects of exercise. The room was packed with interested doctors. The moderator assured us that all three researchers were "well-funded," which I guess is high praise in research circles.

William Haskell, M.D., of Stanford University’s Center on Longevity answered the questions: “How much exercise do we need?” and “How much is too much?” He is on the National Institutes of Health (NIH) committee creating the national exercise guidelines that will be released in October.

One startling conclusion is that the first step is the most valuable. Even minimal exercise is significantly better than none. Just 70 minutes a week (10 minutes a day) of moderate-intensity exercise (such as a very brisk walk) probably gets you half the benefit you can get. Doing 150 minutes a week gets you most of the rest. (Dr. Haskell reported that 90 minutes a week of moderate exercise reduces death rates by 20%.) There is apparently very little additional health benefit from going over 240 minutes a week.

But that 10 to 30 minutes a day is super-important, Dr. Haskell said. Even three days of bed rest causes insulin resistance, even among athletes! So you can imagine what no exercise might do to someone who is already insulin resistant. Even light activity reverses most of this insulin resistance.

Fit vs. Fat
Timothy Church, M.D., M.P.H., Ph.D., of the Pennington Biomedical Research Center at Louisiana State University answered the question, “Which is more important, getting physically fit or losing weight?” He had explored this “fatness vs. fitness” issue for years at The Cooper Institute in Houston, a leading exercise research center.

The short answer was that when it comes to developing Type 2 diabetes, “obesity is somewhat more important than physical activity.” But when it comes to death from cardiovascular disease (heart disease and strokes), fitness is much more important than weight. And since most people with diabetes die from cardiovascular disease, exercise is the most important medicine when it comes to survival for people with diabetes, especially Type 2.

Dr. Church agreed that 10 minutes a day was very valuable and that 150 minutes a week was enough for most people when it comes to fitness. But he cited the DREW (Dose Response to Exercise in Women) study to explain that sustained weight loss requires more work. To lose weight, 150 minutes a week is enough. But to keep it off, you probably will need more like 45 to 60 minutes a day of moderate to vigorous exercise.

Does Weight Training Help?
Gary Hunter, Ph.D., of the University of Alabama showed that there is much more to exercise than walking and running. He cited studies that show that resistance training (usually with weights) increases strength and muscle mass, and decreases fat and inflammation. All of this is good news for people with diabetes. Weight training might be better than aerobics for many people, although combining aerobics and resistance training is best.

Resistance training also tends to make bones stronger and denser. So if you have concerns about osteoporosis, strength training is great medicine.

So the bottom line is that even small amounts of physical activity are extremely helpful. Being a complete couch potato is extremely bad. And you can try almost any kind of activity. It doesn’t have to be all walking.

Does this match up with your experience? I personally think that 150 minutes a week is doable, and most people can feel the benefits quickly, especially in improved mood, but also in things like blood glucose readings. Has it worked like that for you?

If you’re interested in what else went on at ADA, you can see abstracts of all the presentations at

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