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ORCID
https://orcid.org/0000-0001-5768-9708
Access Type
Open Access Thesis
Document Type
thesis
Degree Program
Kinesiology
Degree Type
Master of Science (M.S.)
Year Degree Awarded
2023
Month Degree Awarded
February
Abstract
Stretch activation (FSA) is the delayed increase in fiber specific tension (force per cross-sectional area) following a rapid stretch and can improve muscle performance during repetitive cyclical contractions. Historically considered minimal in skeletal muscle, our recent work showed the ratio ofstretch- to calcium-activated specific tension (FSA/F0) increased from 10 to 40% with greater inorganic phosphate (Pi) levels in soleus muscle fibers (Straight et al., 2019). Given Pi increases with muscle fatigue, we hypothesize that FSA helps maintain force generation during fatigue. To test this, FSA, induced by a stretch of 0.5% fiber length, was examined during Active (pCa 4.5 (pCa = -log([Ca2+]), pH 7.0, Pi 5 mM), High Ca2+ Fatigue (pCa 4.5, pH 6.2, Pi 30 mM) and Low Ca2+ Fatigue (pCa 5.1, pH 6.2, Pi 30 mM) in fibers expressing myosin heavy chain (MHC) I, IIA, IIX and IIB isoforms from soleus and extensor digitorum longus muscles of C57BL/6NJ mice. F0 of all MHC isoforms decreased from Active to High Ca2+ Fatigue to Low Ca2+ Fatigue, as expected. In MHC IIX and IIB fibers, FSA occurred under all conditions and FSA/F0 increased from Active (17-20%) to High Ca2+ Fatigue (32-35%) to Low Ca2+ Fatigue (42-44%). In MHC IIA fibers, FSA/F0 increased similarly to MHC IIX and IIB fibers from Active (14%) to High Ca2+ Fatigue (32%) but stayed elevated under Low Ca2+ Fatigue (35%). For MHC I fibers, no discernable FSA was apparent in either High – or Low Ca2+ Fatigue, leaving an FSA/F0 value in Active only ( 4%). These results show that FSA is a significant modulator of specific tension production under fatiguing conditions in fast-contracting muscle fibers. This mechanism could play an important physiological role during cyclical contractions, when the antagonistic muscle rapidly stretches the agonist muscle, by reducing the effect of fatigue on specific tension production.
DOI
https://doi.org/10.7275/32898994
First Advisor
Mark S. Miller
Second Advisor
Jane A. Kent
Third Advisor
Edward E. Debold
Fourth Advisor
Douglas A. Swank
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Recommended Citation
Woods, Philip C., "Stretch Activation During Fatigue Improves Relative Force Production in Fast-Contracting Mouse Skeletal Muscle Fibers" (2023). Masters Theses. 1279.
https://doi.org/10.7275/32898994
https://scholarworks.umass.edu/masters_theses_2/1279
Included in
Cellular and Molecular Physiology Commons, Laboratory and Basic Science Research Commons, Other Kinesiology Commons