title: Reliability of isometric subtalar pronator and supinator strength testing.
abstract: BACKGROUND
  Due to the specific anatomy of the subtalar joint with its oblique axis, isometric pronator and supinator strength is not well documented. The purpose of this study was to determine intra- and between-session reliability of pronator and supinator strength and lower leg muscle activity measurements during maximum voluntary isometric contractions (MVIC).
  
  
  METHODS
  Pronator and supinator peak torques (PT), with and without supplementary visual muscle strength biofeedback (FB), and muscular activities of peroneus longus (PL) and tibialis anterior (TA) were assessed twice 3 days apart by the same examiner in 21 healthy young male adults (mean age: 27.6 years; SD = 3.9). Limits of agreement (LoA) and minimum detectable change (MDC) were evaluated.
  
  
  RESULTS
  By applying FB, reliability of both pronator and supinator PT was improved: LoA were reduced from 32% to 26% and from 20% to 18% and MDC from 20% to 15% and from 16% to 12% in supinator and pronator PT, respectively. Learning effects in pronator and supinator PT (p < 0.05), which were present without FB, were eliminated using FB. Except for TA during pronation, muscle activities showed low reliability indicated by LoA of 51% to 79%.
  
  
  CONCLUSIONS
  Using supplementary biofeedback, isometric subtalar pronator and supinator strength testing is reliable in healthy subjects. LoA of 18% and 26% have to be exceeded for pronator and supinator PT, respectively, to detect relevant effects in repeated measures.
authors.affiliation: Biomechanics Laboratory, Institute of Sport and Movement Sciences, University of Duisburg-Essen, Gladbeckerstraße 182, Essen, 45141 Germany.
authors.forename: Marco
authors.initials: M
authors.lastname: Hagen
authors.affiliation: Clinics for Orthopaedic and Trauma Surgery, University Hospital St. Joseph, Ruhr-University Bochum, Gudrunstraße 56, Bochum, 44791 Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Lahner
authors.affiliation: Biomechanics Laboratory, Institute of Sport and Movement Sciences, University of Duisburg-Essen, Gladbeckerstraße 182, Essen, 45141 Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Winhuysen
authors.affiliation: Department of Applied Human Movement Science, Technische Universität Chemnitz, Chemnitz, 09107 Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Maiwald
keywords: Isometric muscle strength; Limits of agreement; Minimum detectable change; Pronation; Subtalar joint; Supination