title: Intramuscular pain modulatory substances before and after exercise in women with chronic neck pain.
abstract: BACKGROUND
  In peripheral tissue, several substances influence pain and pain modulation. Exercise has been found to decrease pain and improve function for chronic pain conditions, but how and why exercise produces beneficial effects remains unclear. This study investigates whether aspects of pain and concentrations of substances with algesic, analgesic and metabolic functions differ between women with chronic neck shoulder pain (CNSP) and healthy women (CON) and whether changes are found after an exercise intervention for CNSP.
  
  
  METHODS
  Forty-one women with CNSP and 24 CON subjects were included. The participants attended two microdialysis sessions with 4-6 months between the experiments. During this period, the CNSP subjects underwent an exercise intervention. Expression levels of substance P, beta-endorphin, cortisol, glutamate, lactate and pyruvate as well as pain intensity and pressure pain thresholds were analysed.
  
  
  RESULTS
  At baseline, higher concentrations of glutamate and beta-endorphin and lower concentrations of cortisol in CNSP than CON were found. After exercise, decreased levels of substance P and possibly of glutamate, increased levels of beta-endorphin and cortisol as well as decreased pain intensity and increased pain pressure thresholds were found for CNSP.
  
  
  CONCLUSIONS
  The findings at baseline indicated algesic and analgesic alterations in the painful trapezius muscles. The findings for CNSP after the exercise intervention, with changes in peripheral substances and decreased pain intensity and sensitivity, could reflect a long-term physiological effect of the exercise.
authors.affiliation: Department of Pain and Rehabilitation Center, Linköping University, Sweden.|Department of Medical and Health Sciences (IMH), Linköping University, Sweden.
authors.forename: L
authors.initials: L
authors.lastname: Karlsson
authors.affiliation: Department of Pain and Rehabilitation Center, Linköping University, Sweden.|Department of Medical and Health Sciences (IMH), Linköping University, Sweden.
authors.forename: B
authors.initials: B
authors.lastname: Gerdle
authors.affiliation: Department of Pain and Rehabilitation Center, Linköping University, Sweden.|Department of Medical and Health Sciences (IMH), Linköping University, Sweden.|Occupational and Environmental Medicine, Department of Clinical and Experimental Medicine (IKE), Faculty of Health Sciences, Linköping University, Sweden.|Centre of Occupational and Environmental Medicine, UHL, County Council, Linköping, Sweden.
authors.forename: B
authors.initials: B
authors.lastname: Ghafouri
authors.affiliation: Department of Pain and Rehabilitation Center, Linköping University, Sweden.|Department of Medical and Health Sciences (IMH), Linköping University, Sweden.
authors.forename: E
authors.initials: E
authors.lastname: Bäckryd
authors.affiliation: Department of Pain and Rehabilitation Center, Linköping University, Sweden.|Department of Medical and Health Sciences (IMH), Linköping University, Sweden.
authors.forename: P
authors.initials: P
authors.lastname: Olausson
authors.affiliation: Department of Pain and Rehabilitation Center, Linköping University, Sweden.|Department of Medical and Health Sciences (IMH), Linköping University, Sweden.
authors.forename: N
authors.initials: N
authors.lastname: Ghafouri
authors.affiliation: Department of Pain and Rehabilitation Center, Linköping University, Sweden.|Department of Medical and Health Sciences (IMH), Linköping University, Sweden.
authors.forename: B
authors.initials: B
authors.lastname: Larsson
mesh_terms: D000328:Adult; D002908:Chronic Disease; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D018698:Glutamic Acid / Q000097:blood; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D019344:Lactic Acid / Q000097:blood; D017551:Microdialysis; D008875:Middle Aged; D019547:Neck Pain / Q000097:blood* / Q000628:therapy*; D010147:Pain Measurement; D017288:Pain Threshold; D019289:Pyruvic Acid / Q000097:blood; D020069:Shoulder Pain / Q000097:blood* / Q000628:therapy*; D013373:Substance P / Q000097:blood; D064171:Superficial Back Muscles / Q000378:metabolism; D055815:Young Adult; D001615:beta-Endorphin / Q000097:blood
chemical_list: D013373:Substance P; D019344:Lactic Acid; D018698:Glutamic Acid; D001615:beta-Endorphin; D019289:Pyruvic Acid; D006854:Hydrocortisone