Musculoskeletal neck-shoulder pain : a new ambulant myofeedback intervention approach

Persisting musculoskeletal complaints in the neck-shoulder region are highly prevalent and associated with high health care and community costs in industrialized countries. The mechanisms underlying the development and perpetuation of these complaints have not fully been identified yet, but explanatory models and hypotheses generally acknowledge a role to abnormal muscle activation patterns. From a physiological perspective the painspasm- pain and the pain-adaptation models ascribe an important role to abnormal muscle activation. However, the leading hypothesis in this field is the Cinderella hypothesis, which suggests that lack of complete muscle relaxation, rather than abnormal muscle activation levels, is relevant for developing and perpetuating complaints. The hypothesis has especially been investigated in subjects with (computer) work-related neck-shoulder complaints, in whom contraction levels are relatively low but continuous over a long time frame. A purely physiological approach of musculoskeletal neck-shoulder complaints related to abnormal muscle activation patterns is according to the commonly adopted biopsychosocial approach not tenable. Within this approach the fear-avoidance and the avoidance-endurance models are relevant, describing the role of cognitions and behaviour in perpetuating pain and disability, and also indirectly addressing the reflected effects on muscle activation patterns. As such, normalisation of muscle activation patterns has been a starting point for developing an intervention strategy for treating musculoskeletal neckshoulder pain. An appropriate method for this purpose may be ambulant myofeedback training based on the Cinderella hypothesis, which provides feedback to the subject when muscle relaxation is insufficient. This feedback is anticipated to increase muscle relaxation levels contributing to recovery in terms of pain and disability, but likely other factors like cognitions and behavioural characteristics are important for outcome after myofeedback training as well. The ambulant Cinderella-based myofeedback approach is deviating from traditional feedback studies in that feedback is provided when the muscle is insufficiently relaxed rather than when muscle activation exceeds a certain threshold, and in that it enables continuous monitoring. This makes it potentially more effective than traditional feedback approaches. This thesis aimed at evaluating the effects and mechanisms of ambulant Cinderella-based myofeedback training in subjects with persistent musculoskeletal neckshoulder pain, primarily focusing on subjects with neck-shoulder complaints related to work but also exploring its effects in subjects with Whiplash Associated Disorder (WAD).