title: Changed activation, oxygenation, and pain response of chronically painful muscles to repetitive work after training interventions: a randomized controlled trial.
abstract: The aim of this randomized controlled trial was to assess changes in myalgic trapezius activation, muscle oxygenation, and pain intensity during repetitive and stressful work tasks in response to 10 weeks of training. In total, 39 women with a clinical diagnosis of trapezius myalgia were randomly assigned to: (1) general fitness training performed as leg-bicycling (GFT); (2) specific strength training of the neck/shoulder muscles (SST) or (3) reference intervention without physical exercise. Electromyographic activity (EMG), tissue oxygenation (near infrared spectroscopy), and pain intensity were measured in trapezius during pegboard and stress tasks before and after the intervention period. During the pegboard task, GFT improved trapezius oxygenation from a relative decrease of -0.83 ± 1.48 μM to an increase of 0.05 ± 1.32 μM, and decreased pain development by 43%, but did not affect resting levels of pain. SST lowered the relative EMG amplitude by 36%, and decreased pain during resting and working conditions by 52 and 38%, respectively, without affecting trapezius oxygenation. In conclusion, GFT performed as leg-bicycling decreased pain development during repetitive work tasks, possibly due to improved oxygenation of the painful muscles. SST lowered the overall level of pain both during rest and work, possibly due to a lowered relative exposure as evidenced by a lowered relative EMG. The results demonstrate differential adaptive mechanisms of contrasting physical exercise interventions on chronic muscle pain at rest and during repetitive work tasks.
authors.affiliation: Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense M, Denmark. ksogaard@health.sdu.dk
authors.forename: Karen
authors.initials: K
authors.lastname: Søgaard
authors.forename: Anne Katrine
authors.initials: AK
authors.lastname: Blangsted
authors.forename: Pernille Kofoed
authors.initials: PK
authors.lastname: Nielsen
authors.forename: Lone
authors.initials: L
authors.lastname: Hansen
authors.forename: Lars L
authors.initials: LL
authors.lastname: Andersen
authors.forename: Pernille
authors.initials: P
authors.lastname: Vedsted
authors.forename: Gisela
authors.initials: G
authors.lastname: Sjøgaard
mesh_terms: D000328:Adult; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009209:Myofascial Pain Syndromes / Q000175:diagnosis / Q000503:physiopathology* / Q000534:rehabilitation*; D009784:Occupational Diseases / Q000503:physiopathology* / Q000534:rehabilitation*; D010100:Oxygen / Q000378:metabolism; D010101:Oxygen Consumption; D020127:Recovery of Function / Q000502:physiology; D016896:Treatment Outcome
chemical_list: D010100:Oxygen