title: Potentiation of the triceps brachii during voluntary submaximal contractions.
abstract: BACKGROUND
  The effects of postactivation potentiation (PAP) on evoked contractions are well understood, but less is known about the effect of PAP on voluntary submaximal contractions. Using a measure of neuromuscular efficiency (NME) [NME = (mV EMG / Nm torque)] we explored the effects of PAP in the triceps brachii at two muscle lengths.
  
  
  METHODS
  Evoked twitch and NME were compared at short (40° elbow flexion) and long (120°) muscle lengths. At each length, 12 subjects performed a contraction of 25% maximum voluntary contraction (MVC) torque before and after a potentiating MVC.
  
  
  RESULTS
  Twitch torque potentiated more at short length (216.9 ± 169.3%) than at long length (77.3 ± 32.6%), but PAP moderately improved NME only at short length (12.2 ± 8.7%).
  
  
  CONCLUSIONS
  The greater capacity for PAP at the short length is reflected by greater NME. Compared with evoked responses, the relatively small change in NME suggests a different and more modest role of PAP during voluntary submaximal contractions.
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: Arthur J
authors.initials: AJ
authors.lastname: Cheng
authors.forename: Charles L
authors.initials: CL
authors.lastname: Rice
mesh_terms: D000328:Adult; D001132:Arm / Q000502:physiology*; D001696:Biomechanical Phenomena / Q000502:physiology; D004551:Elbow Joint / Q000502:physiology; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D019415:Torque; D014836:Volition / Q000502:physiology*; D055815:Young Adult