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Updated: Feb 12, 2026
07:44
An Experimental Study on Colorado Potato Beetle Hibernation Under Natural Conditions
Published on: November 17, 2023
13.4K
Soleus muscle stability in wild hibernating black bears
D A Riley1, J M Van Dyke1, V Vogel1
1Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin , Milwaukee, Wisconsin.
Summary
Hibernating black bears prevent skeletal muscle atrophy, particularly in the soleus muscle, by maintaining fiber size and performance. This study reveals key adaptations in fiber composition and function during hibernation.
Area of Science:
- Comparative physiology
- Skeletal muscle biology
- Hibernation research
Background:
- Hibernating mammals resist skeletal muscle atrophy during prolonged inactivity and fasting.
- Previous studies focused on fast skeletal muscles, but slow muscles are more susceptible to disuse atrophy.
- The black bear's soleus muscle, rich in slow fibers, was investigated for atrophy-sparing mechanisms.
Purpose of the Study:
- To investigate atrophy sparing in the slow soleus muscle of hibernating black bears.
- To analyze changes in fiber type composition, size, and performance characteristics during hibernation.
- To understand the biochemical adaptations preserving muscle function during prolonged dormancy.
Main Methods:
- Histochemical analysis of soleus muscle fiber types (slow vs. fast).
- Biochemical detection of myosin heavy chain isoforms in hybrid fibers.
- Measurement of fiber cross-sectional area relative to body mass.
- Assessment of fiber shortening velocity, specific tension, and normalized power.
Main Results:
- Black bear soleus muscle comprises predominantly slow fibers (84%), with no significant change in percentage during hibernation.
- Fiber size-to-body mass ratio remained stable between summer and hibernating periods.
- A significant increase in hybrid fibers (containing both slow and fast myosin) was observed during hibernation.
- Specific tension and normalized power of both slow and fast fibers were maintained or elevated during hibernation.
Conclusions:
- Black bears exhibit remarkable preservation of soleus muscle structure and function during hibernation.
- Adaptations include stable fiber composition and size, increased hybrid fiber presence, and enhanced contractile properties.
- These findings demonstrate effective atrophy resistance mechanisms in a slow skeletal muscle during prolonged dormancy.
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