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Love your heart – aerobic exercise comes with added benefits for those with diabetes

September 4, 2012 in News

Most of us have heard that exercise is good for the heart; regular aerobic exercise like swimming, jogging, and biking can strengthen the heart and improve cardiac function. Now it appears that the same aerobic exercise that is good for everyone’s heart gives an added benefit to people with diabetes.

Researchers at Johns Hopkins have been studying the impact of diabetes on the heart by using specially bred mice with type 2 diabetes as a model. To start, they looked at the hearts of both the diabetic mice and healthy mice, and used a chemical called isoproterenol to simulate the effect that exercise has on the heart. At the same time, they “fed” the hearts a lot of glucose, to simulate what would happen when the mice were exercising with high blood sugar.

The researchers found that the hearts from the non-diabetic mice handled the excess glucose with no problems. The hearts from the mice with type 2 diabetes did not; they were unable to contract and relax quickly enough to keep up with the increased blood flow during exercise and pump normally.

For the next part of the study, the researchers repeated the combination of isoproterenol and glucose, and added in fatty acids. Fatty acids occur normally in the blood, and play a role in helping cells exchange energy. In the heart, they also help protect the cells from the damaging effects of excess levels of “reactive oxygen species,” a form of free radical.

When we eat too much, the extra energy is stored as fat. When weight gain occurs continuously over a long period of time, we not only become overweight or obese; the stored fats build up to levels that become toxic for the cells. The stored fats crowd out many of the healthy functions of the cells.

During exercise, these stored fats begin to be broken down, and free fatty acids are released into the bloodstream. By adding a high level fatty acids to the mixture of isopoterenol and glucose, researchers at Johns Hopkins simulated this effect.

The double level of fatty acids had no impact on the function of the hearts of the non-diabetic mice; they continued to beat normally and keep up with the added stress of exercise. The effect on the hearts of the diabetic mice was surprising. In the first trial, the hearts of the diabetic mice had trouble keeping up with the extra blood flow. When the fatty acids were added, the hearts not only kept up with the added stress, they improved in function to the level of the hearts from the non-diabetic mice. This suggests that the extra fatty acids released into the blood during exercise can protect the heart from the impairments caused by excess glucose levels.

Another important finding from the study concerned diabetic cardiomyopathy. This complication is a form of heart failure. The study demonstrated that excess glucose levels can prevent the cells in the heart from getting the energy they need. Over time, this lack of energy in the heart muscle tissue causes the mechanical and electrical functions needed to to produce a normal heartbeat to break down, leading to heart failure.

The Johns Hopkins team found that adding glutathione, an important antioxidant, to the hearts of the diabetic mice improved the ability of the muscle tissue to function properly, counteracting the effect some of the damage that can lead to cardiomyopathy. They also found that when the level of fatty acids in the heart was raised, the level of naturally released glutathione increased as well. This suggests that when extra fatty acids are released into the blood by aerobic exercise, the body also releases more glutathione, bathing the heart tissues in two important compounds that can reduce the damage done by excess glucose.

The research team is hoping that these findings will lead to new treatments for diabetics who have trouble bringing their glucose levels under control; there may be a way to use glutathione to prevent some of the heart damage caused by excess glucose. These new treatments will need to be carefully assessed for safety once they are developed, so it will be a while before any safe treatments become available.

However, the other important finding of the study reinforces what previous research has told us. Exercise is of vital importance for everyone, and especially those with diabetes. When you exercise, you are not only gaining the same widely-known strengthening effects for the heart, and helping manage your weight; you are helping your heart deal with the stress caused by high glucose levels.

If you aren’t currently exercising, now is an excellent time to add asking your doctor about a fitness program. The American Diabetes Association also has a page with excellent advice about how to start an exercise program appropriate for you, and how to stay motivated.

If you would like to read ScienceDaily’s orginial news post, you can access the article on their website.





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