title: Continuous Ultrasound Decreases Pain Perception and Increases Pain Threshold in Damaged Skeletal Muscle.
abstract: OBJECTIVE
  Determine whether therapeutic ultrasound (TUS) delivered in a continuous mode reduces pain perception after muscle injury.
  
  
  METHODS
  Randomized, double-blind trial.
  
  
  METHODS
  Institutional laboratory.
  
  
  METHODS
  Twenty young healthy participants (11 females; 9 males; mean age ± SD, 24.1 ± 3.7 years).
  
  
  METHODS
  All subjects performed 50 maximal eccentric contractions of the biceps brachii on a Biodex dynamometer. Criterion measures of isometric force production and serum creatine kinase (CK) activity confirmed tissue damage. Both groups received either TUS or sham treatment everyday starting 24 hours after muscle damage. Muscle soreness and pain were assessed at baseline, 48 hours postdamage, and every other day for 8 days.
  
  
  METHODS
  Muscle pain was assessed with a battery of tests: visual analog scale (VAS), Short-form McGill Pain Questionnaire-2, joint angle changes, and mechanical pressure threshold.
  
  
  RESULTS
  Confirmation of damage occurred with baseline compared to 48 hours after damage of isometric peak torque (N·m; P < 0.01) and CK activity (IU/I; P = 0.03). Our results showed significant treatment group differences in VAS (P = 0.01) and mechanical pressure threshold (P = 0.02) after the third TUS treatment in the distal bicep brachii region.
  
  
  CONCLUSIONS
  Continuous TUS reduced pain perception and increased mechanical pressure threshold in the biceps brachii after muscle damage, specifically near the distal musculotendinous junction.
authors.affiliation: *Department of Health Sciences and Research, Medical University of South Carolina, Charleston, South Carolina; †Escuela de Fisioterapia, Facultad de Salud, Universidad Industrial de Santander, Bucaramanga, Colombia; and ‡Department of Physical Therapy, Duquesne University, Pittsburgh, Pennsylvania.
authors.forename: Stacey E
authors.initials: SE
authors.lastname: Aaron
authors.forename: Diana C
authors.initials: DC
authors.lastname: Delgado-Diaz
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Kostek
mesh_terms: D000328:Adult; D001132:Arm; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000293:injuries*; D063806:Myalgia / Q000628:therapy*; D010147:Pain Measurement; D058748:Pain Perception; D017288:Pain Threshold; D014464:Ultrasonic Therapy; D055815:Young Adult