(RxWiki News) Whether you are an adult or a child, exercise is good for you. Researchers already know that exercise can lower the risk of diabetes in children. But how much exercise is the best protection against diabetes?
The answer may be that more exercise is better. In a recent study, researchers found that overweight or obese children who exercised more were less likely to develop conditions that lead to diabetes.
"Get exercise and stay healthy."
For their study, Catherine Davis, PhD, of the Medical College of Georgia, and colleagues assigned two groups overweight and obese children to do 20 or 40 minutes of aerobic exercise (e.g. walking, running or swimming) per day. A third group of children did their usual amount of activity.
The researchers found that the children who did more exercise were less likely to develop insulin resistance - a condition in which the body does not properly use insulin.
Insulin is a natural hormone the body needs to use glucose (sugar) for energy.
When someone becomes insulin resistant, levels of sugar in the blood can rise, which can lead to prediabetes and diabetes.
The study's results showed a dose-response relationship between the amount children exercised and their levels of insulin resistance.
In other words, the more they exercised, the less insulin resistant they became.
In addition, the researchers found that more exercise was associated with more fat loss. That is, greater amounts of exercise led to larger reductions in both total body fat and visceral fat.
Visceral fat is a kind of fat in the abdomen that surrounds the body's organs. This type of fat has been linked to an increased risk of heart disease and type 2 diabetes.
Studies have shown that aerobic exercise can lower children's risk of metabolic problems that lead to diabetes. The study by Dr. Davis and colleagues is the first to show that there is a dose-response relationship between exercise and metabolic risks in children.
The study involved 222 overweight or obese children who exercised little. Of these, 71 were assigned to exercise 20 minutes per day, 73 were assigned to 40 minutes of exercise per day and 78 stuck to their normal levels of physical activity. These exercise assignments were done 5 days a week for 13 weeks.
Children who were assigned to exercise 40 minutes per day had the largest reductions in insulin area under the curve, or time-averaged insulin levels (a measure of insulin resistance). The 20-minute group had smaller reductions in time-averaged insulin levels, but still larger reductions than children who did not change their amount of activity.
Compared to children who did usual activity, those who did 40 minutes of exercise per day had a difference in total body fat of 1.4 percent. Those who exercised 20 minutes per day had a difference in total body fat of 0.8 percent, compared to those who did usual activity.
Visceral fat sizes in the 40-minute group were 3.9 cm3 less than in the usual activity group. In the 20-minute group, visceral fat sizes were 2.8 cm3 less than in the usual activity group.
The sex or race of the participants did not change the effects of exercise.
The research was funded by the National Institutes of Health and the Spanish Ministry of Education and Science.
The study was published September 19 in The Journal of the American Medical Association (JAMA).