Exercise as it relates to Disease/Aerobic Training vs Resistance Training and Type 2 Diabetes

Background - Type 2 Diabetes Mellitus
Type 2 Diabetes Mellitus(T2DM) is a chronic, metabolic disease that affects people all over the world. Globally, it contributes to 90% of people with diabetes, with very similar results in Australia, representing 85-90% of total overall diabetes cases. It is characterised by elevated levels of glucose in the blood, due to one of two things; the pancreas does not produce enough insulin (insulin deficiency) or the insulin cannot be taken up by the tissues (insulin resistance). T2DM can have chronic detrimental effects on many areas of the body and ultimately affects an individuals quality of life.
 * Heart Complications: increased risk of heart disease, myocardial infarction, ischemic heart disease and stroke
 * Nerve Complications: neuropathy in the feet decreases foot sensitivity and thereby increases chances of foot ulcers, infections and the risk of amputation
 * Eye Complications: retinopathy can lead to blindness
 * Kidney Complications: kidney failure

Risk Factors

Exercise and Type 2 Diabetes Mellitus
 Aerobic Training : Involves repeated and/or continuous movements of the same large muscle groups lasting for a minimum of 10 minutes at a time; such activities include walking, jogging, running, cycling, swimming, aerobics, rhythmical dancing and many sports. When this particular form of exercise is carried out at sufficient intensity and on a frequent basis, it results in an increase in cardiorespiratory fitness.  Resistance Training : Uses muscle strength to perform work against a resistive load; it usually with some degree of weight in the form of body weight, free weights or weight machines. When performed on a regular basis and at a moderate to high intensity level, this type of exercise increases muscular fitness.

During exercise, contraction of the skeletal muscle causes glucose transporter protein-4 (GLUT-4) to translocate to the plasma membrane, and uptake glucose from the bloodstream into the muscle. After just one exercise bout, GLUT-4 concentration can be increased by nearly 4-fold. The ability of GLUT-4 to be translocated to the membrane – independent of the presence of insulin – assists in creating metabolic adaptations that improve insulin sensitivity in T2 diabetics.

While there is currently a wide range of pharmaceutical treatments available to help control T2DM; participation in physical activity is an important aspect that should be included within a treatment plan due to the effects of GLUT-4. Aerobic exercise, resistance exercise and/or a combination of the two, have been shown to have a positive effect on the health status and blood glucose levels of T2 Diabetics,  as well as improving blood lipids,  decreasing blood pressure, reducing the risk of cardiovascular events and mortality and improving overall quality of life.

The degree of these positive effects is variable depending on the form of exercise. Aerobic exercise in particular has shown to have a greater effect on lowering blood glucose concentrations both during the session and for up to 12 hours following exercise, when compared to resistance training. Improvements to glycemic control, insulin sensitivity and VO2max have been shown as a result of aerobic training; further improvements are shown to both glycemic control and insulin sensitivity the higher the training intensity. Only within recent years has resistance training received more attention regarding its effect on glycemic control in individuals with T2D, yet results are still mixed in terms of its benefits and improvements on metabolic abnormalities associated with T2DM. In addition to this, participating in exercise bouts of combined aerobic and resistance training returns benefits superior to either alone.

Recommendations for Exercise Methods
'' Before undertaking any form of exercise, the individual should be checked by a health professional and complete a prescreening tool ( ESSA Screening Tool and Information ). Current health status, medications, mobility range, strength level, and any associated co morbidities must be taken into account and an individualised approach to constructing any exercise program is important. ''

NB: In the interest of the individuals’ safety and to ensure correct technique of resistance exercises’ are being performed in order to maximise benefits, initial supervision and regular assessments should be carried out by a qualified specialist.

In addition to the simple forms of physical activity such as walking, recommendations for aerobic exercise sessions include:

Further Reading/Information Sources
Australian Diabetes Council

Diabetes Australia

National Evidence Based Guideline for Case Detection and Diagnosis of Type 2 Diabetes

Australian Type 2 Diabetes Risk Assessment Tool (AUSDRISK)

WHO Diabetes Fact Sheet

WHO: Definition and Diagnosis of Diabetes Mellitus and Intermediate Hyperglycemia