title: Effect of different approaches to target force on transcranial magnetic stimulation responses.
abstract: BACKGROUND
  The aim of this study was to determine whether the manner in which a target force is approached can influence the electromyographic (EMG) and mechanical parameters evoked by transcranial magnetic stimulation (TMS) during brief muscle contractions.
  
  
  METHODS
  The amplitude of motor-evoked potentials (MEP) and superimposed twitch and the duration of the silent period were recorded in 8 healthy participants in response to TMS delivered during brief isometric voluntary contractions of the quadriceps maintaining a target force (10% and 50% of maximal voluntary force) or gradually increasing or decreasing to reach this point.
  
  
  RESULTS
  MEP and superimposed twitch, unlike the silent period, are influenced by the manner of reaching a low force.
  
  
  CONCLUSIONS
  Clear instructions must be provided to research participants and patients. Rapidly increasing to a target force without exceeding it and maintaining the force before the delivery of TMS results in stable, representative MEP amplitudes.
authors.affiliation: Laboratoire HP2, U1042 INSERM, Université Joseph Fourier, Grenoble, France.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Gruet
authors.forename: John
authors.initials: J
authors.lastname: Temesi
authors.forename: Thomas
authors.initials: T
authors.lastname: Rupp
authors.forename: Guillaume Y
authors.initials: GY
authors.lastname: Millet
authors.forename: Samuel
authors.initials: S
authors.lastname: Verges
mesh_terms: D000328:Adult; D004558:Electric Stimulation; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
keywords: force; motor-evoked potential; muscle contraction; silent period; transcranial magnetic stimulation