Major annual physiological cycles of grizzly (brown) bears.aThree major annual metabolic stages—hibernation, active, and hyperphagia—are indicated along with the letter abbreviation for the corresponding months of the year. Blue line along the perimeter indicates the approximate period of insulin resist...
Muscle atrophy is a physiological response to disuse and malnutrition, but hibernating bears are largely resistant to this phenomenon. Unlike other mammals, they efficiently reabsorb amino acids from urine, periodically activate muscle contraction, and their adipocytes differentially responds to insulin. Th...