In fact, the white muscle that increases with resistance training, age and diabetes helps keep blood sugar in check.
"We wanted to figure out the relationship between muscle types and body metabolism, how the muscles were made, and also what kind of influence they have on diseases like Type 2 diabetes," said Jiandie Lin, Life Sciences Institute faculty member and associate professor at the UM Medical School.
Lin's findings were published online April 7 in Nature Medicine.
People with diabetes see whitening of muscles.
"For a long time, the red-to-white shift was thought to make muscle less responsive to insulin, a hormone that lowers blood sugar," Lin said. "But this idea is far from proven. You lose red muscle when you age or develop diabetes, but is that really the culprit?" Lin said.
White muscle dominates in the bodies of weight-lifters and sprinters - people who require short, intense bursts of energy.
"Most people have a mix of red and white muscles," Lin said.