title: Assessment of the rate of force development scaling factor for the hip muscles.
abstract: BACKGROUND
  The aim of this study was to evaluate test feasibility, validity, and reproducibility of the rate of force development scaling factor (RFD-SF) for the hip muscles.
  
  
  METHODS
  Feasibility was assessed as the testing compliance, validity as the ability to compute the RFD-SF from a linear regression, and reproducibility with a test-retest design in 20 healthy subjects. Reliability and agreement (reproducibility) were evaluated using intraclass correlation coefficient (ICC3,1) and percent standard error of measurement (SEM), respectively.
  
  
  RESULTS
  The RFD-SF testing protocol was completed successfully by all subjects, although the analysis had to be modified for hip rotators. Reliability was high (ICC3,1 > 0.70) for all muscles except hip abductors (ICC3,1 = 0.69) and internal rotators (ICC3,1 = 0.58). Agreement was high for all muscles (SEM < 10%).
  
  
  CONCLUSIONS
  Hip adductor, flexor, and external rotator RFD-SF can be evaluated with confidence, provided the analysis is modified for external rotators, whereas hip abductor and internal rotator RFD-SF assessment is not recommended.
authors.affiliation: Neuromuscular Research Laboratory, Schulthess Clinic, Lengghalde 2, 8008, Zurich, Switzerland; INSERM U1093-Cognition, Action and Sensory Plasticity, University of Burgundy, Dijon, France.
authors.forename: Nicola C
authors.initials: NC
authors.lastname: Casartelli
authors.forename: Romuald
authors.initials: R
authors.lastname: Lepers
authors.forename: Nicola A
authors.initials: NA
authors.lastname: Maffiuletti
mesh_terms: D000328:Adult; D005240:Feasibility Studies; D005260:Female; D006621:Hip Joint / Q000502:physiology*; D006801:Humans; D016014:Linear Models; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D009469:Neuromuscular Junction / Q000502:physiology; D010827:Physiology / Q000379:methods*; D016059:Range of Motion, Articular / Q000502:physiology; D015203:Reproducibility of Results; D012399:Rotation
keywords: hip; isometric; neuromuscular function; rate of force development scaling factor; regression line