New York: A moderate aerobic exercise program alone—without weight loss—has been found to improve insulin sensitivity in both lean and obese sedentary adolescents, as part of a new study.
Accepted for publication in The Endocrine Society`s Journal of Clinical Endocrinology and Metabolism (JCEM), a report on the study highlights the fact that insulin is a hormone produced in the pancreas that permits glucose to enter cells to be used for energy or stored for future use by the body.
To maintain normal blood sugar levels in obese adolescents, given that they are resistant to insulin, their bodies have to increase the production of insulin.
However, increasing insulin production places higher demands on the pancreas, and thus can exhaust pancreatic beta cells to the point that they no longer produce sufficient amounts of insulin to keep blood sugar levels normal, which might subsequently lead to type 2 diabetes.
"Because weight loss can be difficult to achieve and maintain in obese sedentary children, the purpose of this study was to determine whether a controlled exercise program, without any diet intervention and with no intention of weight loss, would improve fat distribution and sensitivity to insulin," said Dr. Agneta Sunehag, of Baylor College of Medicine and senior author of the study.
"We found that a 12-week moderate aerobic exercise program consisting of four 30-minute workouts a week increased fitness and improved insulin sensitivity in both lean and obese adolescents," Sunehag added.
During the study, 29 adolescents—14 lean and 15 obese—completed the 12-week moderate aerobic exercise program.
The exercise sessions required the subjects to work out on a treadmill, elliptical or bicycle.
The goal of each exercise session was to get the participants`` heart rate to increase to at least 70 percent of their maximum capacity.
The researchers measured the subjects’ glucose and insulin concentrations both before and after the exercise program.
Cardiovascular fitness was determined using an oxygen consumption test which consists of measuring oxygen uptake of the participant during a treadmill exercise where speed and incline is increased every three minutes until the subject reaches his maximum exercise capacity.
"Many studies include both diet and exercise interventions, which makes it difficult to determine which intervention is most effective and best accepted by adolescents. Our findings show that exercise alone can increase fitness and improve insulin sensitivity, making an aerobic program like the one used in this study a potential useful tool in preventing obesity-related illnesses," said Sunehag.