Increasing the Strength of the Heart and Lungs Can Lower the Chances of Getting Diabetes and Related Problems

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Cardiorespiratory fitness attenuates metabolic risk independent of abdominal subcutaneous and visceral fat in men, by S. Lee and colleagues. Diabetes Care 28:895-901, 2005.

What is the problem and what is known about it so far?

Being overweight or obese (seriously overweight) can lead to many health problems, such as high blood pressure and high cholesterol, among others. People who are overweight or obese and have both high blood pressure and high cholesterol are likely to get diabetes if they don't improve their health.

Why did the researchers do this particular study?

People can improve their cardiorespiratory fitness, or the strength of their heart and lungs, by walking, jogging, biking, and other physical activities. Exercising is known to lower body fat and to make the heart and lungs stronger. But it is still not known whether people who exercise are less likely to have high blood pressure and high cholesterol if they remain overweight. The researchers wanted to compare men of the same weight and body make-up to find out whether men who exercised had a lower chance of getting the conditions related to diabetes.

Who was studied?

A total of 297 healthy white men were studied at Queens University in Kingston, Ontario, Canada, and the Cooper Clinic in Dallas, Texas. The men in the study were all nonsmokers and were not taking any medications at the time of the study.

How was the study done?

After not eating for 12 hours, each man had their total cholesterol (a waxy fat-like substance that builds up in the blood vessels), HDL (“good”) cholesterol, triglycerides (a type of fat found in the blood), and blood glucose measured. Each man was weighed and had his waist size measured. Then, the subjects walked on a treadmill at different speeds and inclines to measure the fitness of their heart and lungs. Researchers looked at all of this information to see whether there was a link between heart and lung fitness and the conditions related to diabetes (high blood pressure, high cholesterol, and overweight or obesity).

What did the researchers find?

Men whose heart and lungs were more fit had a lower chance of getting the conditions related to diabetes, even if they were overweight. They had lower blood pressure, lower triglycerides, and higher HDL (“good”) cholesterol. There were no differences in blood glucose levels between men who had similar fitness levels. Researchers found that by increasing the strength of their heart and lungs, people can lower their risk of getting deadly diseases by 44%.

What are the limitations of the study?

Genetic factors play a large role in a person's fitness level, meaning that the strength of a person's heart and lungs also has to do with the medical history of a person's family. Not everyone may be able to reach a high fitness level.

Researchers did not look at what the men ate. The foods we eat affect our blood pressure, cholesterol, and weight.

Because only men were looked at in this study, researchers do not know if their findings will be the same for women.

What are the implications of the study?

To avoid becoming overweight or obese, adults should spend more time doing physical activities. By increasing their fitness levels, adults will be less likely to get the conditions related to diabetes and other deadly diseases.

FOR MORE INFORMATION

The Metabolic Syndrome

Available at

Exercise and Diabetes

The “I Hate to Exercise” Book for People With Diabetes, by Charlotte Hayes (Alexandria, Va., ADA, 2001).

Exercise capacity and body composition as predictors of mortality among men with diabetes, by T.S. Church and colleagues. Diabetes Care 27:83–88, 2004.