title: Discrete quasi-linear viscoelastic damping analysis of connective tissues, and the biomechanics of stretching.
abstract: The time- and frequency-dependent properties of connective tissue define their physiological function, but are notoriously difficult to characterize. Well-established tools such as linear viscoelasticity and the Fung quasi-linear viscoelastic (QLV) model impose forms on responses that can mask true tissue behavior. Here, we applied a more general discrete quasi-linear viscoelastic (DQLV) model to identify the static and dynamic time- and frequency-dependent behavior of rabbit medial collateral ligaments. Unlike the Fung QLV approach, the DQLV approach revealed that energy dissipation is elevated at a loading period of ∼10s. The fitting algorithm was applied to the entire loading history on each specimen, enabling accurate estimation of the material's viscoelastic relaxation spectrum from data gathered from transient rather than only steady states. The application of the DQLV method to cyclically loading regimens has broad applicability for the characterization of biological tissues, and the results suggest a mechanistic basis for the stretching regimens most favored by athletic trainers.
authors.affiliation: Department of Mechanical Engineering & Materials Science, and NSF Center for Engineering MechanoBiology, Washington University in St. Louis, St. Louis, MO, USA.
authors.forename: Behzad
authors.initials: B
authors.lastname: Babaei
authors.affiliation: Department of Bioengineering, Rice University,Houston, TX, USA.
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Velasquez-Mao
authors.affiliation: Orthopaedic Surgery, School of Medicine, Washington University School of Medicine, St. Louis, MO, USA.
authors.forename: Stavros
authors.initials: S
authors.lastname: Thomopoulos
authors.affiliation: Department of Biochemistry & Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA.
authors.forename: Elliot L
authors.initials: EL
authors.lastname: Elson
authors.affiliation: Musculoskeletal Research Center, Department of Bioengineering, University of Pittsburgh Pittsburgh, USA.
authors.forename: Steven D
authors.initials: SD
authors.lastname: Abramowitch
authors.affiliation: Department of Mechanical Engineering & Materials Science, and NSF Center for Engineering MechanoBiology, Washington University in St. Louis, St. Louis, MO, USA. Electronic address: genin@wustl.edu.
authors.forename: Guy M
authors.initials: GM
authors.lastname: Genin
mesh_terms: D000465:Algorithms; D000818:Animals; D001696:Biomechanical Phenomena; D003238:Connective Tissue / Q000502:physiology*; D004548:Elasticity; D016014:Linear Models; D008954:Models, Biological; D052580:Muscle Stretching Exercises; D011817:Rabbits; D013314:Stress, Mechanical; D014783:Viscosity
keywords: Discrete quasi-linear viscoelastic model; Ligament; Quasi-linear viscoelasticity; Relaxation spectrum; Storage and loss modulus; Stress relaxation