DESPITE hardly moving during the five to seven months they hibernate, black
bears retain muscle tissue and strength. Henry Harlow and his colleagues at the
University of Wyoming found that the bears lost only 22 per cent of their muscle
strength during hibernation, and only 10 to 15 per cent of their protein (
Nature, vol 409, p 997). A human would lose 85 per cent of their strength
and 90 per cent of their protein if bedridden for a similar period.
The researchers believe the bears need good muscle condition to be ready to
fight predators such as wolves if disturbed in their cave. By studying muscle
biopsies, Harlow has shown that the bears maintain their muscle using nitrogen
from urea. 鈥淭hey don鈥檛 eat, drink or pee for 130 days,鈥� says Harlow. 鈥淭he bear
reabsorbs urea through the bladder and uses the nitrogen to conserve
辫谤辞迟别颈苍.鈥�