Knowledge: Animals, Bears Hibernating

(sleeping bears and their physical conditions)

How Bears Power-Nap

For most people, staying in shape means getting regular exercise. Take a vacation from the gym and your hard-earned sixpack goes soft. Imagine if you could sleep for five months and still wake up fit as a fiddle.

• According to research described in the February 23, 2001, Nature, this is in fact just how bears emerge from hibernation.
• Henry J. Harlow of the University of Wyoming and his colleagues found that hibernating black bears lose less than 23 percent of their strength during their 130-day winter slumber.
• Humans, in contrast, would experience a 90 percent strength loss if they were immobile for so long.
• Incredibly, when the team took muscle biopsies from denned bears in early and late winter, they found that the skeletal muscle cells did not dwindle in size or number-nor did they lose their protein content or oxidative capacity.
• The researchers suggest that the bears may be maintaining their muscles by drawing on protein reserves from elsewhere in the body, and by shivering.
• "Understanding these processes in hibernating bears," the team writes, "may provide new insight into treating muscle disorders and into the effects of prolonged hospital bed confinement, antigravity and long-distance space travel on humans."