title: Muscle activation and contraction: constitutive relations based directly on cross-bridge kinetics.
abstract: This paper reviews recent work aimed at deriving tractable constitutive relations for skeletal muscle from biophysical cross-bridge theories. Discussion is focused on a model proposed previously by the first author (the Distribution-Moment Model), which emphasizes the important role of the moments of the actin-myosin bond-distribution function. The theory leads to a relatively simple third order state variable model for contraction dynamics in which the state variables are the three lowest order moments of the bond-distribution function; further, these three moments have simple macroscopic interpretations as muscle stiffness, force, and elastic energy. New results are presented on the formulation of a compatible model for excitation-contraction coupling, and this model requires the introduction of only one more state variable--the free calcium concentration.
authors.affiliation: Washington University, Department of Mechanical Engineering, St. Louis, MO 63130.
authors.forename: G I
authors.initials: GI
authors.lastname: Zahalak
authors.forename: S P
authors.initials: SP
authors.lastname: Ma
mesh_terms: D000199:Actins / Q000378:metabolism / Q000502:physiology; D001696:Biomechanical Phenomena; D002118:Calcium / Q000378:metabolism / Q000502:physiology; D004548:Elasticity; D007700:Kinetics; D008954:Models, Biological; D009119:Muscle Contraction / Q000502:physiology*; D009132:Muscles / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism / Q000502:physiology
chemical_list: D000199:Actins; D009218:Myosins; D002118:Calcium