title: Increased trapezius pain sensitivity is not associated with increased tissue hardness.
abstract: Fatiguing exercise can affect muscle pain sensitivity and muscle hardness, as seen with work-related neck and shoulder pain. Objective methods to assess muscle pain sensitivity are important because the reliability of manual assessment is generally poor. The aim of this study was (1) to compare coexistence of tender points identified by manual palpation and pressure algometry or hardness assessments and (2) to examine the influence of exercise on muscle pain sensitivity and hardness. Fourteen sites in the upper trapezius muscle were selected for assessments in 12 healthy subjects. Pressure pain thresholds and muscle hardness were examined by computer-controlled pressure algometry at baseline, immediately after static or dynamic exercise, and 20 minutes after static or dynamic exercise. Before recording of pressure pain thresholds, the trapezius muscle was examined for tender points by manual palpation. Two sites with low pressure pain thresholds were typical locations for tender points, and these were the least hard sites. However, manually detected tender points were often (29%) not colocalized with most sensitive sites according to the pressure algometry. A heterogeneous distribution of pressure pain sensitivity and muscle hardness was found in the upper trapezius. The short duration of exercise until exhaustion did not change muscle sensitivity or muscle hardness in asymptomatic muscles.
  
  
  CONCLUSIONS
  This study confirms clinical findings with heterogeniosity in pain sensitivity and hardness across the upper trapezius muscle. Developments of new techniques that objectively can identify tender points are important, but thus far, manual palpation is best clinical practice.
authors.affiliation: Laboratory for Musculoskeletal Pain and Motor Control, Center for Sensory-Motor Interaction (SMI), Aalborg University, Aalborg, Denmark.
authors.forename: Helle
authors.initials: H
authors.lastname: Andersen
authors.forename: Hong-You
authors.initials: HY
authors.lastname: Ge
authors.forename: Lars
authors.initials: L
authors.lastname: Arendt-Nielsen
authors.forename: Bente
authors.initials: B
authors.lastname: Danneskiold-Samsøe
authors.forename: Thomas
authors.initials: T
authors.lastname: Graven-Nielsen
mesh_terms: D000328:Adult; D004548:Elasticity; D015444:Exercise / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009333:Neck / Q000503:physiopathology*; D019547:Neck Pain / Q000503:physiopathology*; D010147:Pain Measurement / Q000379:methods; D017288:Pain Threshold / Q000502:physiology*; D010808:Physical Examination; D010812:Physical Stimulation; D011312:Pressure; D012782:Shoulder / Q000503:physiopathology*; D020069:Shoulder Pain / Q000503:physiopathology*; D055815:Young Adult