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Expectancy Reduces Symptoms but not Functional Impairment Following Exercise Induced Musculoskeletal Injury

Hedderson William C. MS ATC CAT(C); Dover, Geoffrey C. PhD, CAT(C), ATC; George, Steven Z. PT, PhD; Crow, Joshua A. MS; Borsa, Paul A. PhD, ATC
The Clinical Journal of Pain: Post Acceptance: February 02, 2017
doi: 10.1097/AJP.0000000000000484
Original Article: PDF Only


To quantify the extent to which the participant-provider interaction influences the response to sham treatment following exercised-induced acute musculoskeletal pain.


Forty participants between the ages of 18 and 35 volunteered for the study. Participants came to the laboratory for three test sessions 48-hours apart (Day 1, 3 and 5). During the initial session, baseline measures were assessed and participants underwent a fatigue protocol for the biceps brachii. Participants were then assigned to a positive expectation or a no-expectation condition before receiving a sham laser therapy treatment. The positive expectation group received symptom improvement priming prior to their sham treatment. Participants allocated to the no-expectation condition received no feedback prior to the sham treatment. Maximum voluntary isometric contraction (MVIC); relaxed elbow angle (RANG); visual analogue scale (VAS); and the QuickDash (QD) questionnaire were used as outcome measures.


The positive expectation group had a significant reduction in perceived pain compared to the no-expectation group at day 3 follow-up, with the mean scores being 34.65 mm (SE=4.44) compared to 49.4 mm (SE=5.79) respectively. There were no between-group differences with respect to MVIC, QD or RANG outcomes. In addition, there were no significant between-group differences observed with expected pain on follow-up visits, the effect sizes were d=0.26 on day 1 for day 3 and d=0.51 on day 3 for day 5.


Positive expectations before a sham treatment enhanced reduction in pain intensity but did not improve functional impairments following exercise induced acute musculoskeletal injury.

The authors declare no conflict of interest.

Reprints: William Hedderson, MSc, ATC, CAT(C), Department of Applied Physiology and Kinesiology, Rm 100FLG, 1864 Stadium Rd, Gainesville, FL, 32611 (e-mail:

Received May 26, 2016

Accepted January 24, 2017

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