title: Skin-textile friction and skin elasticity in young and aged persons.
abstract: OBJECTIVE
  The mechanical properties of human skin are known to change with ageing, rendering skin less resistant to friction and shear forces, as well as more vulnerable to wounds. Until now, only few and contradictory results on the age-dependent friction properties of skin have been reported. This study has investigated in detail the influence of age on the friction of human skin against textiles.
  
  
  METHODS
  In vivo skin-friction measurements on a force plate were combined with skin analyses concerning elasticity, hydration, pH value and sebum content. Thirty-two young and 28 aged persons rubbed their volar forearm in a reciprocating motion against various textiles on the force plate, using defined normal loads and sliding velocities, representing clinically relevant contact conditions.
  
  
  RESULTS
  Mean friction coefficients ranged from 0.30 +/- 0.04 (polytetrafluoroethylene) to 0.43 +/- 0.04 (cotton/polyester). No significant differences in the friction properties of skin were found between the age groups despite skin elasticity being significantly lower in the aged persons. Skin hydration was significantly higher in the elderly, whereas no significant differences were observed in either skin pH value or sebum content.
  
  
  CONCLUSIONS
  Adhesion is usually assumed to be the dominant factor in skin friction, but our observations imply that deformation is also an important factor in the friction of aged skin. In the elderly, lower skin elasticity and skin turgor are associated with more pronounced skin tissue displacements and greater shear forces during frictional contact, emphasizing the importance of friction reduction in wound-prevention programmes.
authors.affiliation: Laboratory for Protection and Physiology, Empa, Swiss Federal Laboratories for Materials Testing and Research, St. Gallen CH-9014, Switzerland.
authors.forename: L-C
authors.initials: LC
authors.lastname: Gerhardt
authors.forename: A
authors.initials: A
authors.lastname: Lenz
authors.forename: N D
authors.initials: ND
authors.lastname: Spencer
authors.forename: T
authors.initials: T
authors.lastname: Münzer
authors.forename: S
authors.initials: S
authors.lastname: Derler
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D003020:Clothing; D055119:Elastic Modulus / Q000502:physiology; D005260:Female; D017276:Friction; D006801:Humans; D008297:Male; D008875:Middle Aged; D012879:Skin Physiological Phenomena; D012882:Skin Tests / Q000379:methods*; D013499:Surface Properties; D013784:Textiles; D055815:Young Adult