Increase in muscle nociceptive substances and anaerobic metabolism in patients with trapezius myalgia: microdialysis in rest and during exercise

Pain. 2004 Dec;112(3):324-334. doi: 10.1016/j.pain.2004.09.017.


Local metabolic changes are suggested to be involved in muscle pain development in humans. Nineteen women with chronic work-related trapezius myalgia (TM) and 20 healthy female controls (CON) were studied during baseline rest, 20 min repetitive low-force exercise, and 120 min recovery. Interstitial serotonin (5-HT), glutamate, lactate, pyruvate, and blood flow were determined by microdialysis in the trapezius muscle. Baseline pressure pain threshold (PPT) was lower (143+/-18 (TM) vs. 269+/-17 (CON)kPa) (mean+/-SEM), pain intensity (visual analogue scale, VAS) higher (33+/-5 vs. 2+/-1mm), muscle 5-HT higher (22.9+/-6.7 vs. 3.8+/-1.3 nmol/l), and glutamate higher (47+/-3 vs. 36+/-4 micromol/l) in TM than in CON (all P<0.05), whereas muscle blood flow was similar in groups. Furthermore, muscle pyruvate was higher (180+/-15 vs. 135+/-12 micromol/l) and lactate higher (4.4+/-0.3 vs. 3.1+/-0.3 mmol/l) in TM than in CON (P<0.001). In response to exercise, VAS and glutamate increased in both TM and CON (all P<0.05). In TM only, lactate and pyruvate increased significantly (P<0.02), whereas blood flow increased to similar levels in both groups. During the initial 20 min recovery period, blood flow remained increased in TM (P<0.005) whereas it decreased to baseline levels in CON. In conclusion, patients with chronic work-related TM have increased levels of muscle 5-HT and glutamate that were correlated to pain intensity (r=0.55, P<0.001) and PPT (r=-0.47, P<0.001), respectively. In addition, TM was associated with increased anaerobic metabolism, whereas a normal rise in blood flow was seen with exercise. These findings indicate that peripheral nociceptive processes are active in work-related TM.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Creatine / blood
  • Female
  • Glutamic Acid / metabolism
  • Humans
  • L-Lactate Dehydrogenase / blood
  • Lactic Acid / metabolism
  • Microdialysis / methods
  • Muscle, Skeletal / metabolism
  • Muscle, Skeletal / pathology
  • Occupational Diseases
  • Pain / metabolism*
  • Pain / physiopathology
  • Pain Measurement
  • Physical Exertion / physiology*
  • Pyruvic Acid / metabolism
  • Regional Blood Flow / physiology
  • Rest / physiology*
  • Serotonin / metabolism
  • Spectrophotometry
  • Time Factors
  • Ultrasonography / methods


  • Serotonin
  • Lactic Acid
  • Glutamic Acid
  • Pyruvic Acid
  • L-Lactate Dehydrogenase
  • Creatine