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dc.contributor.advisorFaulkner, John A.
dc.contributor.authorWard, Christine E.
dc.description19 p.en_US
dc.description.abstractHypotheses were tested that a muscle stimulated at a frequency that elicited a maximal rate of force development (dP/dto) was fully activated during after-loaded isotonic contractions by the time the muscle developed the force necessary to displace the after-load and consequently the shortening velocity was maximum. whereas a muscle stimulated at a rate that elicited maximum tetanic force (Po) was not fully activated and under similar circumstances could not displace after-loads at maximum velocities. As controls for fully activated muscle, the same muscles were stimulated to develop Po and were then released to each after-load. Soleus muscles from 14 mice were stimulated directly in vitro at 25º C. Shortening velocities of each muscle were measured at 13 different after-loads using 4 different protocols: stimulation at a frequency that produced Po (approximately 90 Hz) with an after-loaded isotonic contraction: stimulation at 90 Hz to Po with a quick-release to each after-load; stimulation at a frequency that produced dP/dto (approximately 250 Hz) with an after-loaded isotonic contraction; or stimulation at 250 Hz to Po with a quick-release to each after-load. The maximum velocity of unloaded shortening (V max) was extrapolated from the force-velocity relationship. A significant difference was observed between the V max of isotonic contractions at 90 Hz (V max=4.17±0.l4 Lf/s) and that at 250 Hz (V max=4.82±O.l4 Lf/s). Based on a repeated measures analysis of variance of the velocities at 13 after-loads, I concluded that soleus muscles were not fully activated when stimulated at a frequency that produced Po unless stimulated to Po and subsequently quick-released to the after-loads. whereas muscles stimulated at a frequency that produced dP/dto were fully activated in all cases except during isotonic contractions at after-loads above 0.40. Furthermore, the extrapolation of measured velocities of a whole muscle to V max is not valid and the practice should be discontinued.en_US
dc.description.sponsorshipDepartment of Physiology. University of Michigan Medical School. Ann Arbor, Michigan.
dc.publisherKalamazoo Collegeen_US
dc.relation.ispartofKalamazoo College Biology Senior Individualized Projects Collection
dc.relation.ispartofseriesSenior Individualized Projects. Biology;
dc.rightsU.S. copyright laws protect this material. Commercial use or distribution of this material is not permitted without prior written permission of the copyright holder.
dc.titleThe Force-Velocity Relationship of the Soleus Muscles of Mice During After-Loaded Isotonic Contractions and After-Loaded Isotonic Releasesen_US
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  • Biology Senior Individualized Projects [1550]
    This collection includes Senior Individualized Projects (SIP's) completed in the Biology Department. Abstracts are generally available to the public, but PDF files are available only to current Kalamazoo College students, faculty, and staff.

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