Active Voice: Using the Latest Exercise Guidelines for Type 2 Diabetes to Halt the Epidemic
By Sheri R. Colberg, Ph.D., FACSM
Viewpoints presented in SMB commentaries reflect opinions of the authors and do not necessarily reflect positions or policies of ACSM.
Sheri R. Colberg, Ph.D., FACSM, is a professor in the Human Movement Sciences Department at Old Dominion University in Norfolk, Virginia. Her research has focused on the benefits of exercise training in type 2 diabetes. See the Dec. 2010 issue of Medicine and Science in Sports and Exercise® for the joint position statement, "Exercise and Type 2 Diabetes," for which Dr. Colberg chaired the writing group.
The U.S. is being overwhelmed by gloomy projections of a rapid rise in cases of diabetes mellitus. Recently, the Centers for Disease Control and Prevention predicted that one of every three Americans will have diabetes by 2050. Moreover, more than half of Americans may develop diabetes or prediabetes – putting them at high risk of developing type 2 diabetes – within the next ten years, according to a new report by health insurer UnitedHealth Group. UnitedHealth Group also projected that diabetes and prediabetes together will account for ten percent of total health care spending by 2020, with an annual cost of almost $500 billion and a total cost of $3.35 trillion over the next decade.
Can anything be done to prevent or reverse the impending diabetes tsunami that is threatening not only the U.S. but also the world? The latest evidence-based research on physical activity and type 2 diabetes – reported in a newly-released joint position statement by ACSM and the American Diabetes Association – unequivocally shows that regular exercise plays a major role in preventing and controlling insulin resistance, prediabetes, type 2 diabetes, gestational diabetes mellitus and costly diabetes-related health complications.
Admittedly, much of the information in this joint position statement is not entirely new; in fact, it reiterates that both aerobic and resistance training improve insulin action, at least acutely, and can improve blood glucose levels, lipids, blood pressure, cardiovascular risk, mortality and quality of life. What is newsworthy, however, is the recommendation that individuals with type 2 diabetes get at least 150 minutes a week of moderate-to-vigorous aerobic exercise spread out at least three days during the week, with no more than two consecutive days between bouts of aerobic activity.
Previous jointly issued ACSM/AHA guidelines (2007) recommended 150 minutes of moderate activity (30 minutes, 5 days per week) or 60 minutes of vigorous activity (20 minutes, 3 days per week) for all adults, whereas recent U.S. federal guidelines (2008) that form the basis of the U.S. National Physical Activity Plan recommended 150 minutes of moderate activity or 75 minutes of vigorous activity, or an equivalent combination, each week. In contrast, most people with type 2 diabetes do not have sufficient aerobic capacity to sustain vigorous activity (~10 METs) for 75 minutes each week, and they may have orthopedic or other health limitations. Accordingly, most diabetic individuals will require at least 150 minutes of moderate-to-vigorous aerobic exercise per week to achieve optimal cardiovascular risk reduction, although some benefits – including improved blood glucose management – may be gained from lower exercise volumes, and further benefits will likely result from additional activity.
Another important recommendation made by the joint position statement is to include regular training of varying types, including moderate-to-vigorous resistance training at least two or three days per week. Recent studies have shown resistance training to be as important as (perhaps even more important than) aerobic activity in diabetes management. In fact, combining aerobic and resistance training may bestow additional glycemic benefits. All individuals with type 2 diabetes or prediabetes are also encouraged to increase their total daily unstructured physical activity (e.g., standing, gardening, housework and walking). Finally, flexibility training may be included, but it should not replace other recommended types of physical training.
Many physicians appear unwilling or cautious about prescribing exercise to individuals with diabetes for a variety of reasons, such as the presence of health-related complications. However, the majority of people with type 2 diabetes can exercise safely, as long as certain precautions are taken (outlined in the position statement), and most can engage in brisk walking without needing physician approval. Therefore, the presence of diabetes complications should not be used as an excuse to avoid participation in physical activity.
In summary, including an exercise program or other means of increasing overall physical activity is critical for optimal health in individuals with type 2 diabetes. It is also part of the decisive lifestyle changes (including dietary improvements) that we must strive to implement worldwide in order to prevent the projected explosion of diabetes and prediabetes over the next few decades. We need to work collectively to stop diabetes before it stops us. The time to take action is now – one (literal) step at a time!