title: Reliability of measures of quadriceps muscle function using magnetic stimulation.
abstract: BACKGROUND
  Magnetic stimulation can be used to assess muscle function by calculating voluntary activation using an interpolated twitch during maximal voluntary contractions (MVCs) and control twitches to potentiated muscle. In this study we assessed the reliability of torque, electromyography (EMG), and voluntary activation variables.
  
  
  METHODS
  Fifteen men completed 5 testing sessions (2 familiarization and 3 reliability trials) to assess quadriceps femoris muscle function. Intra- and interday reliability levels of torque and EMG variables were estimated using typical error ± 90% confidence limits, expressed as percentage [coefficient of variation (CV)] and intraclass correlation coefficient. The smallest worthwhile change was calculated as 0.2 × between-participant standard deviation.
  
  
  RESULTS
  Intra- and interday torque variables for MVC were reliable (CV < 4%, ICC 0.98, and CV < 5%, ICC 0.99, respectively). EMG variables were less reliable than torque variables, with CVs ranging from 7% to 18%.
  
  
  CONCLUSIONS
  Magnetic stimulation of the femoral nerve is a reliable method for assessing muscle function.
authors.affiliation: School of Exercise Science, Australian Catholic University, 115 Victoria Parade, Fitzroy, 3065, Melbourne, Victoria, Australia.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Tofari
authors.affiliation: School of Exercise Science, Australian Catholic University, 115 Victoria Parade, Fitzroy, 3065, Melbourne, Victoria, Australia.
authors.forename: David A
authors.initials: DA
authors.lastname: Opar
authors.affiliation: School of Exercise Science, Australian Catholic University, 115 Victoria Parade, Fitzroy, 3065, Melbourne, Victoria, Australia.
authors.forename: Justin G
authors.initials: JG
authors.lastname: Kemp
authors.affiliation: Département de Kinésiologie, Université Laval, Quebec City, Quebec, Canada.
authors.forename: Francois
authors.initials: F
authors.lastname: Billaut
authors.affiliation: School of Exercise Science, Australian Catholic University, 115 Victoria Parade, Fitzroy, 3065, Melbourne, Victoria, Australia.
authors.forename: Stuart
authors.initials: S
authors.lastname: Cormack
mesh_terms: D000328:Adult; D004576:Electromyography; D005267:Femoral Nerve; D006801:Humans; D060526:Magnetic Fields; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D052097:Quadriceps Muscle / Q000502:physiology*; D015203:Reproducibility of Results; D019415:Torque; D055815:Young Adult
keywords: EMG; interpolated twitch; magnetic stimulation; reliability; skeletal muscle; torque