| Muscle atrophy is another result of dormancy
that bears must avoid. While protein degeneration during long periods of
inactivity is usually consistent with atrophy of skeletal muscles, studies
have shown the lack of impaired locomotor ability by bears during dormancy
(Tinker et al., 1998). Many studies have shown that concentrations of principle
energy supplying substrates such as glycogen and triglycerides are relatively
unchanged in bears during dormancy. They have also shown that muscle oxidative
capacity remains unchanged during the denning period (Koebel et al., 1991;
Tinker et al., 1998). Therefore, muscle energy metabolism maintains its
capacity in denning bears. Because energy metabolism is maintained, researchers
have concluded little or no muscle atrophy. One study completed by Tinker
et al (1998) poses possible explanations for this phenomenon. They suggest
that the processes of nitrogen recycling to retain skeletal muscle protein
and periodic shivering leads to sustained muscle strength. |
