It is widely believed that aerobic exercise may prevent diabetes. Such kind of exercise increases the insulin sensitivity of the cells. So when you exercise, less insulin is required to keep your blood sugar levels under control.
However, this idea is based on studies whose methodology does not allow a distinction between the roles of aerobic fitness and body fat percentage as risk factors of insulin resistance and type 2 diabetes.
A new study sheds light on this and suggests that good aerobic exercise does not protect children against obesity-induced insulin resistance, which is a key risk factor of type 2 diabetes. Instead of being more physically active and less sedentary time found to be associated with reduced insulin resistance also in obese children.
Eero Haapala, Ph.D., from the Faculty of Sport and Health Sciences at the University of Jyväskylä, said, “Our study clearly shows that aerobic fitness is not associated with insulin resistance when body composition is taken into consideration properly. Moreover, good aerobic fitness doesn’t seem to protect against obesity-induced insulin resistance. It seems that the role of poor aerobic fitness as a risk factor of type 2 diabetes has been grossly exaggerated.”
452 children between 6 and 8 years of age were analyzed during the study. The study explored associations between their aerobic fitness, body fat percentage, physical activity, sedentary time and insulin resistance.
Aerobic fitness was assessed using a maximal exercise test on a cycle ergometer, and body fat percentage by DXA measurement. Physical activity and sedentary time were measured using a combined movement and heart rate sensor, and insulin resistance were assessed by measuring glucose and insulin levels from blood samples.
Scientists found that brisker physical activity and less sedentary time were associated with reduced insulin resistance regardless of the level of aerobic fitness and body fat percentage. It also protected children from obesity.
Dr. Haapala noted, “A key take-home message from our study is that more physical activity and less sedentary time play key roles in the prevention of type 2 diabetes already in childhood. For obese children, these seem to be especially important.”
The study is published in Medicine & Science in Sports & Exercise.