SKELETAL MUSCLE FORCE GENERATION: PARAMETER IDENTIFICATION OF DIFFERENT MATERIAL MODELS TO A CONTRACTION COMBINATION

Frederico Lagemann¹; Jakson Manfredini Vassoler¹

¹ PROMEC-UFRGS

doi:10.20906/CPS/COB-2015-1412

Resumo

Skeletal muscle tissue provides force generation, balance and locomotion for the human body. The main characteristics of this tissue is that they are composed of sarcomeres, which contract upon electrical stimulus. Based on experimental observations, the muscle mechanical behavior exhibit a passive contributions, due to collagen fibers and intrinsic elasticity of the muscle fiber, as well as an active contribution, due to sarcomere contraction, that increases the tissue stiffness. Many authors have been investigating the muscle mechanical behavior. In these studies the attention is given to individual contractions (isometric, eccentric or concentric), but not the combination of them, which are responsible to the most common movements of a skeletal muscle. In general, these models can be applied only to one specific kind of muscle contraction, not being able to predict different contraction combinations. Then, the main objective of this paper is to study and compare the mechanical response of different constitutive models capable to simulate isometric, eccentric and concentric contractions for large strains. In this paper the most promising models are presented and tested to an isometric-eccentric-isometric contraction. Also, to have a fair comparison between the models a parameter identification procedure was performed. The results show that none of the models were capable of representing the expected stress observed in the contraction combination, indicating a need of a new constitutive model that can represent these basic muscle mechanical behaviors. This result was not surprising, since no model was proposed to account for muscle contraction combination.

Palavras-chave: skeletal muscle; active-passive behavior; contraction; comparative analyses