Hopker James G, Foad Abigail J, Beedie Christopher J, Coleman Damian A, Leach Geoffrey
Centre for Sports Studies, University of Kent, Chatham, Kent, UK.
Open Access J Sports Med. 2010 Nov 19;1:215-21. doi: 10.2147/OAJSM.S13564. eCollection 2010.
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.
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.
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).
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.
本研究在运动治疗环境中检验了一种惰性安慰剂凝胶对实验诱导的肌肉疼痛的治疗效果。其旨在调查条件性镇痛与干预预期相结合在后续镇痛中所起作用的程度。
参与者为英国一所大学的16名男性和8名女性运动治疗专业学生。在获得机构伦理委员会批准并遵循知情同意程序后，每位参与者在五种条件下接受小腿疼痛刺激，即条件设定、基线前、实验（两次应用安慰剂凝胶）和基线后。在条件设定试验中，参与者确定相当于疼痛评分为6/10的疼痛刺激水平。然后将一种惰性安慰剂凝胶涂抹在该部位，并明确告知这是一种镇痛药。参与者再次接受疼痛刺激，其水平在他们不知情的情况下已降低，从而营造出凝胶产生镇痛效果的印象。在实验条件下，涂抹安慰剂凝胶并记录引发疼痛评分为6/10所需的疼痛刺激水平。
涂抹安慰剂凝胶后，引发疼痛评分为6/10所需的疼痛刺激水平提高了8.2%。安慰剂凝胶的应用显著降低了参与者对肌肉疼痛的感知（P = 0.001）。
受试者对疼痛减轻的体验和预期可能是治疗过程中的主要因素。在运动治疗环境中应考虑这些因素。
