New Orleans, LA - More than 40 million Americans participate at least once in a form of aerobic exercise every year. Despite the fact that two individuals may participate in the same activity for the same amount of time, one may achieve greater more aerobic capacity. The reason? Genetics.

In 1996, two physiologists began to test their assumptions about artificial selection for low and high aerobic treadmill running capacity in rats. Their purpose was to create low capacity runners (LCR) and high capacity runners (HCR) that could ultimately be developed into contrasting strains for intrinsic (i.e., untrained) aerobic capacity. Now they are able to report the response to selection across nine generations of divergent artificial selection for aerobic treadmill running capacity.

Steven L. Britton and Lauren Gerard Koch, both from the Functional Genomics Laboratory, Medical College of Ohio, Toledo, OH are the research investigators. They will deliver the results of their investigation, “Genetic Models of Aerobic Endurance Running Capacity in Rats,” during the American Physiological Society’s (APS) annual meeting, part of the "Experimental Biology 2002 conference. More than l2,000 will attend the conference, which is being held April 20-24, 2002 at the Ernest N. Morial Convention Center, New Orleans, LA.

Artificial selection for intrinsic aerobic endurance running capacity was started using a genetically heterogeneous stock of rats (N:NIH) as a founder population of 168. Selection for low and high capacity was based upon distance run to exhaustion on a motorized treadmill using a velocity-ramped running protocol.

On average the founder population ran to exhaustion in 355 ± 11 meters. Nine generations of selection produced lines that differed in running capacity by 270 percent with most of the change occurring in the high line (HCR). At generation 9 the LCR ran 230 ± 8 m and the HCR ran 851 ± 36 m at exhaustion. Body weight changed as a correlated trait in response to rats selectively bred for aerobic running capacity. The low line gained weight while the high line lost weight across nine generations (males = 28% and females = 21% difference between the lines).

The large difference in capacity - 270 percent -- between the LCR and HCR demonstrates that useful models are now available for discovering the genes responsible for variation in intrinsic aerobic capacity. The researchers’ immediate plan is to increase the intensity of selection to produce LCR and HCR that are even more widely different in running capacity and make these available for study. In the long-term, inbred strains derived from these lines will assist in efforts to identify genes responsible for both low and high capacity runners.

- end -

The American Physiological Society (APS) is one of the world’s most prestigious organizations for physiological scientists. These researchers specialize in understanding the processes and functions underlying human health and disease. Founded in 1887 the Bethesda, MD-based Society has more than 10,000 members and publishes 3,800 articles in its 14 peer-reviewed journals each year.

***