On sarcomere length stability during isometric contractions before and after active stretching

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dc.contributor.authorJohnston, Kaleena
dc.contributor.authorMoo, Engkuan
dc.contributor.authorJinha, Azim
dc.contributor.authorHerzog, Walter
dc.date.accessioned2019-11-29T21:17:51Z
dc.date.available2019-11-29T21:17:51Z
dc.date.issued2019-11-27
dc.description.abstractSarcomere length (SL) instability and SL non-uniformity have been used to explain fundamental properties of skeletal muscles, such as creep, force depression following active muscle shortening and residual force enhancement following active stretching of muscles. Regarding residual force enhancement, it has been argued that active muscle stretching causes SL instability, thereby increasing SL non-uniformity. However, we recently showed that SL non-uniformity is not increased by active muscle stretching, but it remains unclear if SL stability is affected by active stretching. Here, we used single myofibrils of rabbit psoas muscle and measured SL non-uniformity and SL instability during isometric contractions and for isometric contractions following active stretching at average SLs corresponding to the descending limb of the force-length relationship. We defined isometric contractions as contractions during which mean SL remained constant. SL instability was quantified by the rate of change of individual SLs over the course of steady-state isometric force and SL non-uniformity was defined as deviations of SLs from the mean SL at an instant of time. We found that whereas the mean SL remained constant during isometric contraction, by definition, individual SLs did not. SLs were more stable in the force-enhanced, isometric state following active stretching compared with the isometric reference state. We also found that SL instability was not correlated with the rate of change of SL non-uniformity. Also, SL non-uniformity was not different in the isometric and the post-stretch isometric contractions. We conclude that since SL is more stable but similarly non-uniform in the force-enhanced compared with the corresponding isometric reference contraction, it appears unlikely that either SL instability or SL non-uniformity contribute to the residual force enhancement property of skeletal muscle.en_US
dc.identifier.citationJohnston, K., Moo E., Jinha, A., & Herzog, W. (2019). On sarcomere length stability during isometric contractions before and after active stretching. "Journal of Experimental Biology. 222. 1-8. http://dx.doi.org/10.1242/jeb.209924en_US
dc.identifier.doihttp://dx.doi.org/10.1242/jeb.209924en_US
dc.identifier.urihttp://hdl.handle.net/1880/111266
dc.publisher.facultyKinesiologyen_US
dc.publisher.institutionUniversity of Calgaryen_US
dc.rightsUnless otherwise indicated, this material is protected by copyright and has been made available with authorization from the copyright owner. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.en_US
dc.titleOn sarcomere length stability during isometric contractions before and after active stretchingen_US
dc.typeunknown
ucalgary.item.requestcopytrueen_US
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