VISCOELASTICITY

  1. ELASTICITY

    A MATERIAL'S STIFFNESS, REFLECTED IN THE SLOPE OF ITS PASSIVE LENGTH-TENSION CURVE

  2. VISCOSITY

    A MATERIAL'S ABILITY TO DAMP MOVEMENT BY BECOMING STIFFER AT HIGHER RATES OF ELONGATION

The influences of passive properties like elasticity and viscosity are easy to understand if we consider that muscles and other soft tissues behave like springs. Viscoelastic materials demonstrate hysteresis, a property wherein the tissues' length-tension characteristics differ during loading and unloading. Muscles also demonstrate a related property, thixotropy, which may be explainable at the level of protein molecules by the formation of transient cross-bridges.

Readings that apply these concepts: Becher, J.G., Harlaar, J., Lankhorst, G.J., & Vogelaar, T.W. (1998). Measurement of impaired muscle function of the gastrocnemius, soleus, and tibialis anterior muscles in spastic hemiplegia: A preliminary study. Journal of Rehabilitation Research & Development, 35, 314-26.

Chesworth, B.M., & Vandervoort, A.A. (1989). Age and passive ankle stiffness in healthy women. Physical Therapy, 69, 217-224.

Magnusson, S.P., Aagard, P., Simonsen, E., & Bojsen-Moller, F. (1998). A biomechanical evaluation of cyclic and static stretch in human skeletal muscle. International Journal of Sports Medicine, 19, 310-6.

Oatis, C.A. (1993). The use of a mechanical model to describe the stiffness and damping characteristics of the knee joint in healthy adults. Physical Therapy, 73, 740-749.

Last updated 1-5-01 ©Dave Thompson PT