To quantify the extent to which the participant-provider interaction influences the response to sham treatment following exercised-induced acute musculoskeletal pain.
In total, 40 participants between the ages of 18 and 35 volunteered for the study. Participants came to the laboratory for 3 test sessions 48-hour 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 before their sham treatment. Participants allocated to the no-expectation condition received no feedback before the sham treatment. Maximum voluntary isometric contraction; relaxed elbow angle; visual analog scale; and the QuickDash questionnaire were used as outcome measures.
The positive expectation group had a significant reduction in perceived pain compared with the no-expectation group at day 3 follow-up, with the mean scores being 34.65 mm (SE=4.44) compared with 49.4 mm (SE=5.79), respectively. There were no between-group differences with respect to maximum voluntary isometric contraction, QuickDash, or relaxed elbow angle 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 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.
*Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL
‡Department of Orthopaedic Surgery and Duke Clinical Research Institute, Duke University, Durham, NC
†Department of Exercise Science, Concordia University, Montreal, QC, Canada
The authors declare no conflict of interest.
Reprints: William C. Hedderson, MS, ATC, CAT(C), Department of Applied Physiology and Kinesiology, Rm 100FLG, 1864 Stadium Rd, Gainesville, FL 32611 (e-mail: firstname.lastname@example.org).
Received May 26, 2016
Received in revised form January 13, 2017
Accepted January 24, 2017