title: Placebo effect of an inert gel on experimentally induced leg muscle pain.
abstract: OBJECTIVE
  This study examined the therapeutic effects of an inert placebo gel on experimentally induced muscle pain in a sports therapy setting. It aimed to investigate the degree to which conditioned analgesia, coupled with an expectation of intervention, was a factor in subsequent analgesia.
  
  
  METHODS
  Participants were sixteen male and eight female sports therapy students at a UK University. With institutional ethics board approval and following informed consent procedures, each was exposed to pain stimulus in the lower leg in five conditions, ie, conditioning, prebaseline, experimental (two placebo gel applications), and postbaseline. In conditioning trials, participants identified a level of pain stimulus equivalent to a perceived pain rating of 6/10. An inert placebo gel was then applied to the site with the explicit instruction that it was an analgesic. Participants were re-exposed to the pain stimulus, the level of which, without their knowledge, had been decreased, creating the impression of an analgesic effect resulting from the gel. In experimental conditions, the placebo gel was applied and the level of pain stimulus required to elicit a pain rating of 6/10 recorded.
  
  
  RESULTS
  Following application of the placebo gel, the level of pain stimulus required to elicit a pain rating of 6/10 increased by 8.2%. Application of the placebo gel significantly decreased participant's perceptions of muscle pain (P = 0.001).
  
  
  CONCLUSIONS
  Subjects' experience and expectation of pain reduction may be major factors in the therapeutic process. These factors should be considered in the sports therapeutic environment.
authors.affiliation: Centre for Sports Studies, University of Kent, Chatham, Kent, UK.
authors.forename: James G
authors.initials: JG
authors.lastname: Hopker
authors.forename: Abigail J
authors.initials: AJ
authors.lastname: Foad
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Beedie
authors.forename: Damian A
authors.initials: DA
authors.lastname: Coleman
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Leach
keywords: conditioning; expectation; perception; positive belief; sports therapy