Exercise Capacity Affects Heart Disease Risk
Reported January 25, 2005
(Ivanhoe Newswire) — A new study shows low aerobic exercise capacity is associated with greater risk factors for cardiovascular disease.
Scientists from Norwegian University of Science and Technology, the Medical College of Ohio, Williams College, and the University of Michigan Medical School examined almost 3,000 rats bred for low aerobic exercise capacity. After 11 generations of this artificial selection for exercise capacity, the rats now differ in their ability to use oxygen efficiently and generate the energy it takes to run for long periods of time.
For example, the high-capacity runners in generation 11 can exercise continuously on a treadmill for 42 minutes before exhaustion causes them to stop, whereas the rats with low-capacity average 14 minutes.
“Our goal in selecting and breeding these rats over many generations was to concentrate genetic differences related to exercise capacity,” says scientist Steven Britton, Ph.D.
They found that rats with low aerobic capacity scored higher on risk factors linked to cardiovascular disease, including high blood pressure and vascular function. In addition, they found evidence of mitochondrial dysfunction in the low-capacity rats.
Researchers hypothesize that impaired mitochondrial function may be what links low aerobic capacity and disease. They explain mitochondria generate energy in each cell, which results in the production of the energy-storing molecule called ATP. ATP is used by every cell in the body and is required to pump blood and for cells to be able to take up the right amount of oxygen.
After 11 generations, researchers found low-capacity rats have low levels of proteins required to maintain adequate production of ATP, and the high-capacity rats have accumulated genes that code for increased production of ATP.
Britton says increasing the capacity for exercise is important to anyone who wants to lower their risk of dying from heart attack or stroke. He and his colleagues call for future research to focus on proving a direct cause-and-effect relationship between mitochondrial function and disease.
SOURCE: Science, published online Jan. 20, 2005
