Diabetes is a metabolic disorder exposing the body's inability to process and utilize glucose, which is the name for sugar once it enters the bloodstream. Insulin, a hormone produced by the pancreas, is responsible for carrying glucose out of the bloodstream and into the cell membrane for energy utilization. Type 1 diabetics either don't produce any or cannot produce enough insulin for this to take place; type 2 diabetics' cells are resistant to the insulin. In either case, sugar accumulates in the bloodstream and leads to abnormally high blood sugar levels. Exercise has been touted as "invisible insulin" due to its contribution in increasing insulin-sensitivity among the cells, thus increasing their uptake of blood glucose.
Benefits
Exercise is essential in the prevention and treatment of diabetes. Cardiovascular exercise is known to strengthen the heart. This is important because diabetic adults have a heart disease-related death rate of two to four times that of non-diabetic individuals. Muscle contractions from resistance exercise increase the number of glucose transporting proteins (GluT4) that enhance the amount of glucose carried into muscle cells. This reduces the need for insulin. Too much insulin can cause a severe drop in blood sugar levels--a condition known as hypoglycemia--which reduces exercise performance and is potentially life-threatening.
Exercise Prescriptions
The American College of Sports Medicine recommends that aerobic conditioning should be undertaken four to six days per week. Ideally, exercise should be performed for 20 to 60 minutes, and intensity should be closely monitored and maintained between 40 to 70 percent of your maximum output.
Resistance training should be performed two to three times per week on nonconsecutive days. Perform eight to 10 exercises, executing one to three sets of these exercises for 10 to 15 repetitions at the outset.
Flexibility training also should be a part of the exercise regimen. Stretching enhances circulation, which is a big concern for those diabetics experiencing peripheral neuropathy in the lower extremities. Perform static stretching two to three times per week, holding each stretch for 10 to 30 seconds.
Contraindications
There are times when exercise is contraindicated. Type 1 diabetics should avoid exercise when blood sugar levels are greater than 240 mg/dL prior to exercise; type 2 individuals' levels should be no greater than 300 mg/dL. Those with proliferative retinopathy are advised to avoid strenuous high-intensity exercise. Exercise also is contraindicated in people with severe kidney disease, a loss of protective sensation in the feet, infection or fever.
Tips
Those with diabetes should eat approximately one hour prior to engaging in activity so they will exercise when blood glucose levels are on the rise. Always check sugar levels prior to beginning exercise, and never engage if blood glucose is low. Keep some form of sugar handy during your workout, in case of a sudden drop in blood glucose. It is a good idea to exercise with a partner who is apprised of the risks of hypoglycemia and hyperglycemia--elevated blood sugar--and who knows the response protocols in case of an emergency.
Considerations
Individuals who have had type 2 diabetes for more than 10 years, are over age 35, have had type 1 diabetes in excess of 15 years or who have evidence of the microvascular diseases retinopathy or neuropathy should get medical clearance from a physician before engaging in an exercise regimen. Lower impact activities such as swimming and biking are preferable to walking and jogging for those who have peripheral neuropathy.
References
- "Sports and Fitness Nutrition"; R. Wildman and B. Miller; 2004
- "NSCA's Essentials of Personal Training"; National Strength and Conditioning Association; 2004
