title: Peak torque and rotational stiffness developed at the shoe-surface interface: the effect of shoe type and playing surface.
abstract: BACKGROUND
  Shoe-surface interactions have been implicated in the high number of noncontact knee injuries suffered by athletes at all levels.
  
  
  OBJECTIVE
  To examine shoe-surface interactions on newer field designs and compare these with more traditional shoe-surface combinations. The peak torque and rotational stiffness (the rate at which torque is developed under rotation) were determined.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  A device was constructed to measure the torque versus applied rotation developed between different shoe-surface combinations. Data were collected on 5 different playing surfaces (natural grass, Astroturf, 2 types of Astroplay, and FieldTurf), using 2 types of shoes (grass and turf), under a compressive load of 333 N.
  
  
  RESULTS
  The highest peak torques were developed by the grass shoe-FieldTurf tray and the turf shoe-Astroturf field combinations. The lowest peak torques were developed on the grass field. The turf shoe-Astroturf combination exhibited a rotational stiffness nearly double that of any other shoe-surface combinations.
  
  
  CONCLUSIONS
  The differences in the rotational stiffness across all 10 shoe-surface combinations were greater than those of the peak torques. It is possible that rotational stiffness may provide a new criterion for the evaluation of shoe-surface interface.
  
  
  CONCLUSIONS
  An improved understanding of shoe-surface interactions remains a critical need to improve the design of shoe-surface combinations with the goal of meeting player needs while minimizing injury potential.
authors.affiliation: Department of Applied Biology and Biomedical Engineering, Rose-Hulman Institute of Technology, 5500 Wabash Avenue, Terre Haute, IN 47803, USA. livesay@rose-hulman.edu
authors.forename: Glen A
authors.initials: GA
authors.lastname: Livesay
authors.forename: Dawn R
authors.initials: DR
authors.lastname: Reda
authors.forename: Eric A
authors.initials: EA
authors.lastname: Nauman
mesh_terms: D004867:Equipment Design; D006801:Humans; D012399:Rotation; D012775:Shoes / Q000592:standards*; D013177:Sports; D019415:Torque; D014142:Track and Field; D014481:United States