title: Voluntary rate of torque development is impaired after a voluntary versus tetanic conditioning contraction.
abstract: BACKGROUND
  Both voluntary and evoked conditioning contractions will potentiate muscle twitch contractile properties. The response of a voluntary contraction to each condition type is not well understood but it may be a more functional model than evoked twitch potentiation.
  
  
  METHODS
  Baseline measurements from tibialis anterior included: maximal isometric twitch torque and rate of torque development (RTD); maximal evoked 50-Hz torque; and maximal voluntary ballistic RTD. Potentiation was induced by a 10-s voluntary or tetanic contraction (∽78% MVC), followed by 2 twitches and 2 ballistic contractions.
  
  
  RESULTS
  Twitch properties (torque and RTD) were potentiated equally after each conditioning contraction. Ballistic RTD was greater post-tetanus (390.2 ± 59.3 Nm/s) than post-voluntary (356.4 ± 69.1 Nm/s), but both were reduced from baseline (422.0 ± 88.9 Nm/s).
  
  
  CONCLUSIONS
  Twitch potentiation was similar between conditioning contraction types, but ballistic RTD was lower after post-tetanus than post-voluntary. The results indicate central inhibition or fatigue concurrent with peripheral potentiation.
authors.affiliation: School of Kinesiology, Arthur and Sonia Labatt Health Sciences Building, University of Western Ontario, London, Ontario, N6A 5B9, Canada.
authors.forename: Cameron B
authors.initials: CB
authors.lastname: Smith
authors.forename: Matti D
authors.initials: MD
authors.lastname: Allen
authors.forename: Charles L
authors.initials: CL
authors.lastname: Rice
mesh_terms: D000328:Adult; D004558:Electric Stimulation; D004576:Electromyography; D005071:Evoked Potentials / Q000502:physiology; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D019415:Torque
keywords: ballistic contraction; dorsiflexion; evoked contraction; post-activation potentiation; voluntary contraction