Short range stiffness elastic limit depends on joint velocity

JOURNAL OF BIOMECHANICS

卷:44

Article

de Vlugt, Erwin¹  van Eesbeek, Stijn¹  Baines, Patricia¹  Hilte, Joost¹  Meskers, Care G. M.²  de Groot, Jurriaan H.² 

[1] Delft Univ Technol, Dept Biomech Engn, Fac Mech Engn, Lab Neuromuscular Control, NL-2628 CD Delft, Netherlands

[2] Leiden Univ, Med Ctr, Dept Rehabil Med, Lab Kinemat & Neuromech, NL-2333 ZA Leiden, Netherlands

关键词: Short range stiffness;    Joint stiffness;    Muscle;    Cross-bridges;    Elastic limit;    Model;    Identification;   

DOI  :  10.1016/j.jbiomech.2011.05.022

来源: Elsevier

【 摘 要 】

Muscles behave as elastic springs during the initial strain phase, indicated as short range stiffness (SRS). Beyond a certain amount of strain the muscle demonstrates a more viscous behavior. The strain at which the muscle transits from elastic- to viscous-like behavior is called the elastic limit and is believed to be the result of breakage of cross-bridges between the contractile filaments. The aim of this study was to test whether the elastic limit, measured in vivo at the wrist joint, depended on the speed of lengthening. Brief extension rotations were imposed to the wrist joint (n=8) at four different speeds and at three different levels of voluntary torque using a servo controlled electrical motor. Using a recently published identification scheme, we quantified the elastic limit from measured joint angle and torque. The results showed that the elastic limit significantly increased with speed in a linear way, indicating to a constant time of approximately 30 ms before cross-bridges break. The implications for movement control of the joint are discussed. (c) 2011 Elsevier Ltd. All rights reserved.

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