Changes in cognitive-behavioral factors and muscle activation patterns after interventions for work-related neck-shoulder complaints: Relations with discomfort and disability

Objectives: Knowledge regarding the working mechanism of an intervention is essential for obtaining a better understanding of the intervention and contributes to optimize its outcome. This study aimed at investigating whether changes in cognitive-behavioral factors and muscle activation patterns after myofeedback training and ergonomic counseling were associated with outcome, in subjects with work-related musculoskeletal neck-shoulder complaints. Methods: Seventy-nine symptomatic subjects received either myofeedback with ergonomic counseling (Mfb/EC) or ergonomic counseling alone (EC). Outcome measures discomfort and disability, and process factors catastrophizing, pain control, fear-avoidance beliefs, and muscle activation patterns were assessed at baseline, after the interventions (T0), and at 3 months follow-up (T3). Mixed modeling techniques were used for analysis. Results: Outcome in terms of discomfort and disability was generally comparable between both interventions. Catastrophizing was significantly reduced and fear-avoidance beliefs about work slightly increased after the interventions, but no consistent changes in muscle activation patterns were observed. Changes in discomfort were especially associated with changes in catastrophizing at T0 and T3, but R2 was low (\0.14). Reduced catastrophizing at T0 and T3, and also reduced fear-avoidance beliefs about work at T3, were related to reduced disability (R2 between 0.30 and 0.40). No differences between the two intervention groups were observed. Conclusions: Intervention effects were generally non-specific and findings suggested that cognitive-behavioral factors underlie the outcome of these interventions rather than changes in muscle activation patterns. Emphasizing these factors during therapy may increase the beneficial outcome of occupational interventions