Capacity for Aerobic Exercise Linked to Risk of Heart Disease

Low exercise capacity in rats associated with high levels of many CV disease risk factors.

ANN ARBOR, MI - If your New Year's resolution to exercise is now just a distant memory, there are some rats at the University of Michigan Medical School that may convince you to climb back on the treadmill.

A new research study, to be published in the Jan. 21 issue of Science, found that rats selected and bred for low aerobic exercise capacity had more cardiovascular disease risk factors than rats bred for high exercise capacity. The study was conducted by scientists from the Norwegian University of Science and Technology, the Medical College of Ohio, Williams College and the U-M Medical School.

The rats in the study are the product of 11 generations of artificial selection for exercise capacity conducted by U-M scientists Steven Britton, Ph.D., and Lauren Gerard Koch, Ph.D. Although they are all descended from the same founder population of genetically mixed lab rats, the experimental rats now differ substantially 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 on average before exhaustion forces them to stop, while the low-capacity runners average only 14 minutes. The overall difference in running capacity between the two groups of rats in the Science study was 347 percent.

The most clinically useful finding reported in the paper was the close association in the experimental rats between low aerobic exercise capacity and high scores for risk factors linked to metabolic syndrome