rats bred to run

From Reuters:

WASHINGTON, Jan 20 (Reuters) – Rats that were “born to run” not only outpaced their less-talented cousins but also were naturally less prone to heart disease, a finding that may help explain why exercise prevents heart death, researchers said on Thursday. …

[Researcher Steven] Britton [of the University of Michigan] and colleagues bred rats for 11 generations to be good or poor runners.

Then they tested their ability to exercise, without training them first, so that differences could not be attributed to practice.

Their high-capacity runners can exercise on a little rodent treadmill for 42 minutes on average before becoming exhausted, while the low-capacity runners average only 14 minutes. It is a 347 percent difference in capacity, they report in Friday’s issue of the journal Science.