Exercise as Therapy: Insulin Resistance

Considerable knowledge has been accumulated in recent decades concerning the significance of physical activity in the treatments of number of diseases. Today, exercise is indicated in the treatment of a large number of medical disorders. In the medical world, it is traditional to prescribe the evidence-based treatment known to be the most effective and entailing the fewest side effects or risks.1 Evidence has suggested that in select cases exercise therapy is just as effective as medical treatment—and in situations more effective –or it adds to the effect.Exercise therapy can have two known clinical effects. It can directly affect the pathogenesis by improving symptoms of the underlying disease, or it can enhance physical fitness, strength, and quality of life of the patient.  Exercise therapy does not represent a paradigm change—it is rather the accumulated knowledge is now so extensive that it has to be implemented. Exercise therapy can have clinical effects, either by directly affecting the disease pathogenesis by improving dominant symptoms of the underlying disease or by enhancing physical fitness, strength and hence quality of life in patients weakened by disease. The goal is that all patients should exercise so that they benefit from the positive effect of prevention of other diseases.1

Background

Insulin Resistance can cause impaired glucose tolerance. About ~40% of people with impaired glucose tolerance will develop type 2 diabetes within 5-10 years. While some remain insulin resistant, others will regain normal glucose tolerance.1 Physical activity, including appropriate endurance and resistance training, is a major therapeutic modality for type 2 diabetes. Unfortunately, too often physical activity is an underutilized therapy. Favorable chances in glucose tolerance and insulin sensitivity usually deteriorate within 72 hours of the last exercise session: consequently, regular physical activity is imperative to sustain glucose-lowering effects and improved insulin sensitivity.2

Evidence for Physical Training

Few studies have examined the isolated effect of training on the prevention of diabetes in patients with impaired glucose tolerance, but there is good evidence for a beneficial effect of combined physical training and dietary modification.1 Few studies have examined the isolated  effects of training and the prevention of diabetes. However, there is evidence that  when combining physical activity and dieting will result in benefits,  Chinese study subdivided 577 people with impaired glucose tolerance into four groups: diet alone, physical exercise, diet and physical exercise and control, and followed them for 6 years. The risk of diabetes was reduced by 31% (P<0.03) in the diet group, by 46% (P<0.0005) in the exercise group and by 42% (P<0.005) in the diet and exercise group.1

Type and Amount of Training

Most of the information available concerns aerobic training of moderate intensity over a long period of time Most of the information given is based on aerobic training done at a moderate intensity for a long time period., but strength conditioning with many repetitions enhances insulin sensitivity in experimental situations and is probably effective in the prevention of type 2 diabetes). Also, strength conditioning (done in experiments) with multiple repetitions enhances insulin sensitivity and may be effective in preventing type 2 diabetes. Lastly, muscular strength and cardiorespiratory fitness are known to have independent and joint inverse associations with the prevalence of metabolic syndrome.1

References:

1 Pedersen, B.K., & Saltin, B. (2006). Evidence for prescribing exercise as therapy in chronic disease. Scandinavian Journal of Medicine & Science in Sports, (16)S1, 3-63. doi:10.1111/j.1600-0838.2006.00520.x

2Albright, A., Franz, M., Hornsby, G., Kriska, A., Marrero, D., Ullrich, I., & Verity, L.S. (2000). American College of Sports Medicine position stand. Exercise and type 2 diabetes. Journal of Medicine and Science in Sports and Exercise 37(7), 1345-1360. doi: 10.1097/00005768-200007000-00024