Muscular force production after concentric contraction
2008 (English)In: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 41, no 11, 2422-2429 p.Article in journal (Refereed) Published
The steady-state force following active shortening does not reach the maximum isometric force associated with the final length. Isolated extensor digitorum longus and soleus muscles from mice (NMRI strain) were used to investigate the force produced by a muscle, and some parameters hypothetically influencing this shortening-induced force depression. The muscles were pre-stimulated at fixed length, shortened and then held isometrically to give maximum post-shortening forces, before de-stimulation. The shortening magnitude was 0.18. 0.36 or 0.72 mm (about 2-7% of optimal length), time of shortening was chosen as 0.03, 0.06 and 0.12 s, and final length as +0.72. 0 and -0.72mm, related to optimal length. The mechanical work during active shortening was evaluated by integrating the product of force and shortening velocity over the shortening period. The results show a positive correlation between the force depression and the mechanical work. whereas the force depression was not correlated to the velocity of shortening. Depression of the passive force component was also observed following all stimulations. Experiments show that the fully stimulated redevelopment of isometric force following concentric contraction follows a time function similar to the creation of force when isometric muscle is initially stimulated. The conclusion is that the isometric force development after active shortening can be well described by an asymptotic force which is decided by the produced work, and the initial isometric time constant.
Place, publisher, year, edition, pages
2008. Vol. 41, no 11, 2422-2429 p.
mouse muscles, concentric contractions, force depression, history, dependence, muscular work, cat soleus muscle, skeletal-muscle, length relationship, isometric, force, descending-limb, frog-muscle, depression, enhancement, stretch, relaxation
IdentifiersURN: urn:nbn:se:kth:diva-17816DOI: 10.1016/j.jbiomech.2008.05.019ISI: 000259129000012ScopusID: 2-s2.0-48149107349OAI: oai:DiVA.org:kth-17816DiVA: diva2:335861
QC 201005252010-08-052010-08-052012-05-25Bibliographically approved