title: Viscoelastic response of the finger pad to incremental tangential displacements.
abstract: The finger pads of eight subjects were loaded by tangential displacement (x-perpendicular to the long axis of the finger) of a contacted surface when the distal and proximal interphalangeal joints (DIP and PIP, respectively) were alternately constrained. The finger pad responded in a linearly viscoelastic manner during loading, but exhibited highly nonlinear behavior upon unloading. The observed tangential force (F(T)) relaxations were nonlinear and could be modeled well by a logarithmic function. The average F(T) relaxation duration (tau) was 11.8 s. Apparent tangential stiffness (kT), determined by F(T) after relaxation, varied linearly with normal force. With the DIP joints constrained the fingers showed significantly larger stiffness than with the PIP joints constrained (p<0.001). Implications for finger force coordination studies are discussed.
authors.affiliation: Department of Kinesiology, The Pennsylvania State University, University Park, 16802, USA. tcp120@psu.edu
authors.forename: Todd C
authors.initials: TC
authors.lastname: Pataky
authors.forename: Mark L
authors.initials: ML
authors.lastname: Latash
authors.forename: Vladimir M
authors.initials: VM
authors.lastname: Zatsiorsky
mesh_terms: D003238:Connective Tissue / Q000502:physiology*; D004548:Elasticity; D005385:Fingers / Q000502:physiology*; D006801:Humans; D010812:Physical Stimulation / Q000379:methods*; D012879:Skin Physiological Phenomena; D013314:Stress, Mechanical; D014783:Viscosity