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The Effects of Muscle Starting Length on Work Loop Power Output of Isolated Mouse Soleus and Extensor Digitorum Longus Muscle

Shelley, S.P.
James, Rob S.
Tallis, J.
Publication Date
2024-04-01
End of Embargo
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Rights
(c) 2024 The Authors. Exlusively licensed to the Company of Biologists. Full-text reproduced according to the re-use rights as stated by CoB (https://www.biologists.com/user-licence-1-1/)
Peer-Reviewed
Yes
Open Access status
embargoedAccess
Accepted for publication
2024-03-27
Institution
Department
Awarded
Embargo end date
2025-04-30
Additional title
Abstract
Force–length relationships derived from isometric activations may not directly apply to muscle force production during dynamic contractions. As such, different muscle starting lengths between isometric and dynamic conditions could be required to achieve maximal force and power. Therefore, this study examined the effects of starting length [±5–10% of length corresponding to maximal twitch force (L0)] on work loop (WL) power output (PO), across a range of cycle frequencies, of the soleus (SOL) and extensor digitorum longus muscle (EDL; N=8–10) isolated from ∼8 week old C57 mice. Furthermore, passive work was examined at a fixed cycle frequency to determine the association of passive work and active net work. Starting length affected maximal WL PO of the SOL and EDL across evaluated cycle frequencies (P0.494). For the SOL, PO produced at −5% L0 was greater than that at most starting lengths (P0.6), except −10% L0 (P=0.135, d1.08), except versus −5% L0 (P=0.124, d0.163, d<1.04). For the SOL, higher passive work was associated with reduced PO (Spearman's r=0.709, P<0.001), but no relationship was observed between passive work and PO of the EDL (Pearson's r=0.191, r2=0.04, P=0.184). This study suggests that starting length should be optimised for both static and dynamic contractions and confirms that the force–length curve during dynamic contractions is muscle specific.
Version
Published version
Citation
Shelley SP, James RS and Tallis J (2024) The Effects of Muscle Starting Length on Work Loop Power Output of Isolated Mouse Soleus and Extensor Digitorum Longus Muscle. Journal of Experimental Biology. 227(8): jeb247158.
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Article
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Notes
The full-text of this article will be released for public view at the end of the publisher embargo on 30 Apr 2025.