title: Postactivation potentiation of force is independent of h-reflex excitability.
abstract: The contractile history of muscle can potentiate electrically evoked force production. A link to voluntary force production, related in part to an increase in reflex excitability, has been suggested.
  
  
  OBJECTIVE
  Our purpose was to quantify the effect of postactivation potentiation on voluntary force production and spinal H-reflex excitability during explosive plantar flexion actions.
  
  
  METHODS
  Plantar flexor twitch torque, soleus H-reflex amplitudes, and the rate of force development of explosive plantar flexion were measured before and after 4 separate conditioning trials (3 x 5 s maximal contractions).
  
  
  RESULTS
  Twitch torque and rate of force production during voluntary explosive plantar flexion were significantly increased (P < .05) while H-reflex amplitudes remained unchanged. Although twitch torque was significantly higher after conditioning, leading to a small increase in the rate of voluntary force production, this was unrelated to changes in reflex excitability.
  
  
  CONCLUSIONS
  We conclude that postactivation potentiation may result in a minor increase in the rate of voluntary isometric force production that is unrelated to neural excitability.
authors.affiliation: Rehabilitation Neuroscience Laboratory and the School of Physical Education, University of Victoria, Victoria, BC.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Hodgson
authors.forename: David
authors.initials: D
authors.lastname: Docherty
authors.forename: E Paul
authors.initials: EP
authors.lastname: Zehr
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000328:Adult; D019054:Evoked Potentials, Motor / Q000502:physiology*; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D007700:Kinetics; D007866:Leg / Q000502:physiology; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D055815:Young Adult