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Two mechanisms are commonly related to placebo effects: expectations and conditioning. However, the research in this field is focused on laboratory studies with healthy participants. This study aims to identify whether a conditioning procedure with positive induced expectations about spinal manipulative therapy (SMT) will result in greater hypoalgesic effects in adults with chronic low back pain (CLBP) in a clinical trial design.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Methods and analysis<\/jats:title>\n                  <jats:p>This trial will enrol 264 patients with non-specific CLBP, aged 18\u201360 years. Patients will undergo a calibration test to determine the thermal pain threshold for the hidden pain conditioning procedure. Afterward, they will be randomised to one of the three groups: hidden pain conditioning with positive induced expectations\u2014group one (G1); positive expectations\u2014group two (G2) and neutral expectations\u2014group three (G3). Patients will receive instructions to manipulate the expectations. The pretreatment heat pain test will be performed before the SMT and after the intervention patients will undergo again the heat pain intensity test. However, only patients in G1 will receive hidden pain conditioning to reinforce the association between SMT and pain intensity reduction. All patients will undergo five sessions of SMT. The outcomes will be assessed immediately after the last session and at the 6\u2009weeks and 3-month follow-ups. All statistical analyses will be conducted following intention-to-treat principles, and the treatment effects will be determined with linear mixed models.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Ethics and dissemination<\/jats:title>\n                  <jats:p>The Federal University of S\u00e3o Carlos approved this research (Process n\u00b0 52359521.1.0000.5504). All participants will give written informed consent. Dissemination of the results will include publications in peer-reviewed journals and presentations at conferences. If positive expectations and classical conditioning improve outcomes, it may support the administration of such intervention.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Trial registration number<\/jats:title>\n                  <jats:p>\n                     <jats:ext-link xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" ext-link-type=\"clintrialgov\" xlink:href=\"NCT05202704\">NCT05202704<\/jats:ext-link>.<\/jats:p>\n               <\/jats:sec>","DOI":"10.1136\/bmjopen-2022-066199","type":"journal-article","created":{"date-parts":[[2023,4,12]],"date-time":"2023-04-12T13:11:03Z","timestamp":1681305063000},"page":"e066199","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":3,"title":["Investigating the hypoalgesic effects of spinal manipulative therapy using hidden pain conditioning and positive expectation in patients with chronic low back pain: protocol for a randomised controlled trial"],"prefix":"10.1136","volume":"13","clinical-trial-number":[{"clinical-trial-number":"nct05202704","registry":"10.18810\/clinical-trials-gov"}],"author":[{"given":"Helen Cristina","family":"Nogueira Carrer","sequence":"first","affiliation":[{"name":"Department of Physical Therapy, UFSCar, Sao Carlos, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Thamiris Costa de","family":"Lima","sequence":"additional","affiliation":[{"name":"Department of Physical Therapy, UFSCar, Sao Carlos, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Steven Z","family":"George","sequence":"additional","affiliation":[{"name":"Department of Orthopedic Surgery, Duke Clinical Research Institute, Durham, North Carolina, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Felipe Jos\u00e9 Jandre dos","family":"Reis","sequence":"additional","affiliation":[{"name":"Department of Physiotherapy, Instituto Federal do Rio de Janeiro (IFRJ), Rio de Janeiro, Brazil, Rio de Janeiro, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Deise Lilian Costa","family":"Dias","sequence":"additional","affiliation":[{"name":"Department of Physical Therapy, UFSCar, Sao Carlos, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Bianca Emanuelli Saes","family":"Campanha","sequence":"additional","affiliation":[{"name":"Departament of Physical Therapy, Federal University of Sao Carlos, Sao Carlos, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6222-4961","authenticated-orcid":false,"given":"Tha\u00eds Cristina","family":"Chaves","sequence":"additional","affiliation":[{"name":"Department of Physical Therapy, UFSCar, Sao Carlos, Brazil"},{"name":"University of Sao Paulo Faculty of Medicine of Ribeirao Preto, Ribeirao Preto, S\u00e3o Paulo, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"239","published-online":{"date-parts":[[2023,4,12]]},"reference":[{"key":"2025101815203077000_13.4.e066199.1","doi-asserted-by":"crossref","DOI":"10.21037\/atm.2020.02.175","article-title":"Global low back pain prevalence and years lived with disability from 1990 to 2017: estimates from the global burden of disease study 2017","volume":"8","author":"Wu","year":"2020","journal-title":"Ann Transl Med"},{"key":"2025101815203077000_13.4.e066199.2","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(20)30925-9"},{"key":"2025101815203077000_13.4.e066199.3","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(18)30480-X"},{"key":"2025101815203077000_13.4.e066199.4","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(16)30970-9"},{"key":"2025101815203077000_13.4.e066199.5","doi-asserted-by":"crossref","first-page":"1352","DOI":"10.1097\/BRS.0000000000000975","article-title":"Trajectories of symptoms and function in older adults with low back disorders","volume":"40","author":"Deyo","year":"2015","journal-title":"Spine (Phila Pa 1976)"},{"key":"2025101815203077000_13.4.e066199.6","unstructured":"NICE guideline NG59 . 2018 surveillance (exceptional review) of low back pain and sciatica in over 16s: assessment and management (NICE guideline NG59). 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