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Objectives: To examine changes in pain outcomes to fully evaluate the effect of adding sensorimotor training to manual therapy and exercise in patients with chronic neck pain and sensorimotor deficits. Concordance was examined between pain distribution and pain intensity and patient-reported outcomes., Methods: Participants (n=152) were randomly allocated into 4 intervention groups: One group received local neck treatment (NT) comprising manual therapy and exercise and the other 3 groups received additional sensorimotor training (either joint position sense/oculomotor exercises, balance exercises or both). Treatment was delivered twice a week for 6 weeks. Pain and patient-reported outcomes were measured at baseline, posttreatment, and 3-, 6- and 12-month follow-ups., Results: There were greater changes in pain location, extent, and intensity at 6- and 12-month follow-ups in the sensorimotor training groups compared with the NT group ( P <0.05). A greater number of patients in the sensorimotor training groups gained ≥50% reduction in pain extent and intensity relative to the NT group at 6 and 12 months ( P <0.05). Clinical improvement in pain extent was concordant with pain intensity (adjusted kappa=056 to 0.66, %agreement=78.3 to 82.9, P <0.001) and disability (adjusted kappa=0.47 to 0.58, % agreement=73.7 to 79.0, P <0.01) at 3-, 6- and 12-month follow-ups, but not with function and well-being. The concordance tended to decline with time., Discussion: Multiple aspects of the pain experience improved in the longer term by adding sensorimotor training to NT for patients with neck pain and sensorimotor deficits. The concordance between pain and patient-reported outcomes was not always evident and varied over time, suggesting the need for multidimensional assessments of pain., Competing Interests: This work was supported by the Thailand Science Research and Innovation (TSRI): Research Career Development Grant (RSA) [grant number 6180020]. The funder played no role in the design, conduct, or reporting of this study. The authors declare no conflict of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Objective: An association exists between repetitive movements and the development or perpetuation of neck-shoulder muscle pain. The mechanisms underlying this association remain unclear. This observational study investigated the effect of upper trapezius muscle pain on the distribution of upper trapezius activity during repetitive lifting. It was hypothesized that nociception would change the distribution of activity resulting in activation of muscle regions which would not normally be active during the task., Materials and Methods: Healthy men repeatedly lifted a box with a cycle time of 3 seconds for 50 cycles, at baseline, following injection of isotonic and hypertonic saline into the upper trapezius muscle and 15 minutes after the last injection. High-density surface electromyography (EMG) was recorded from the upper trapezius using a grid of 64 electrodes. The EMG amplitude was computed for each location to form a map of the EMG amplitude distribution., Results: During the painful condition, the overall EMG amplitude was lower compared with all other conditions (P<0.05) and in addition, the center of upper trapezius activity was shifted toward the caudal region of the muscle (P<0.01), a region not normally active during the task. The described alterations of muscle activity likely play an important role in the perpetuation of pain during repetitive activity., Discussion: Novel mapping of the spatial distribution of upper trapezius muscle activity showed that nociception induced a redistribution of activity during repetitive lifting. This knowledge provides new insights into the mechanisms underlying the perpetuation of pain with repetitive activity.

Aim: To apply topographical mapping of the electromyography (EMG) amplitude recorded from the upper trapezius muscle to evaluate the distribution of activity and the location of peak activity during a shoulder elevation task in participants with and without myofascial pain and myofascial trigger points (MTrP) and compare this location with the site of the MTrP., Materials and Methods: Thirteen participants with myofascial pain and MTrP in the upper trapezius muscle and 12 asymptomatic individuals participated. High-density surface EMG was recorded from the upper trapezius muscle using a matrix of 64 surface electrodes aligned with an anatomic landmark system (ALS). Each participant performed a shoulder elevation task consisting of a series of 30 s ramped contractions to 15% or 60% of their maximal voluntary contraction (MVC) force. Topographical maps of the EMG average rectified value were computed and the peak EMG amplitude during the ramped contractions was identified and its location determined with respect to the ALS. The location of the MTrP was also determined relative to the ALS and Spearman correlation coefficients were used to examine the relationship between MTrP and peak EMG amplitude location., Results: The location of the peak EMG amplitude was significantly (P<0.05) different between groups (participants with pain/MTrP: -0.32±1.2 cm at 15% MVC and -0.35±0.9 cm at 60% MVC relative to the ALS; asymptomatic participants: 1.0±1.3 cm at 15% MVC and 1.3±1.1 cm relative to the ALS). However, no correlation was observed between the position of the MTrP and peak EMG amplitude during the ramped contractions at either force level (15%: rs=0.039, P=0.9; 60%: rs=-0.087, P=0.778)., Conclusions: People with myofascial pain and MTrP displayed a caudal shift of the distribution of upper trapezius muscle activity compared with asymptomatic individuals during a submaximal shoulder elevation task. For the first time, we show that the location of peak muscle activity is not associated with the location of the MTrP.