The grizzly bear's weight training routine.
Anyone who's ever had his arm in a cast has witnessed the shocking speed with which human muscle disappears when unused. But every winter, bears roll up into a ball and become immobile for months—no eating, drinking, urinating, or defecating—and manage to emerge as lean beasts with virtually all the muscle they started out with. How do they manage burn 4000 calories of fat per day, and still retain all their muscle? Recent research
by Josep M. Argilés of the University of Barcelona Cancer Research Group suggests that during hibernation, bears produce a factor—likely a protein or a hormone—that circulates in their blood and inhibits protein degradation. Argilés and his team took muscle cells from laboratory rats and grew them in dishes with blood from hibernating or non-hibernating bears. Rat muscle cells that were incubated in the hibernating bear blood degraded 40 percent less than those incubated in blood from the non-hibernating bears. If isolated, this factor might benefit patients who lose muscle in pathological situations, such as cancer or AIDS, along with those undergoing long periods of malnutrition, immobilization, or near zero-g