title: Effects of ultrasound and stretch on knee ligament extensibility.
abstract: METHODS
  Randomized, double-blind pre-test and post-test with repeated measures.
  
  
  OBJECTIVE
  To determine whether heating with continuous wattage ultrasound (CWUS) augmented the effects of stretching on ligament extensibility in nonimpaired human subjects.
  
  
  BACKGROUND
  Heating with CWUS, combined with static stretching, is often used to treat ligament "tightness," but "heat and stretch" has not been studied well in vivo.
  
  
  METHODS
  Twenty-one nonimpaired women subjects (aged 31.5 +/- 11.0 years) underwent serial measurements of knee joint displacement (valgus and varus) on a Genucom arthrometer before and after valgus stretch (10 ft-lb x 2.5 minutes). Subjects received either simultaneous CWUS (3 MHz, 1.25 W/cm2) or sham CWUS applied over the medial collateral ligament. Five trials (2 before, 3 after treatment) were conducted with the right knee positioned in 20 degrees of flexion. Subjects received the alternate treatment 28 days later. For each subject, all testing was performed by the same investigator.
  
  
  RESULTS
  Repeated measures ANOVA revealed that stretching, combined with sham CWUS, increased mean valgus displacement from 8.95 degrees (+/-1.72 degrees) to 10.00 degrees (+/-2.10 degrees). Stretching, combined with CWUS, increased mean valgus displacement from 9.24 degrees (+/-2.36 degrees) to 10.48 degrees (+/-2.54 degrees). This was a 13.4% change from the control condition.
  
  
  CONCLUSIONS
  Heating with CWUS did not augment the effects of stretching. "Heat and stretch" with CWUS may not be more effective than stretching alone for increasing the extensibility of dense connective tissue.
authors.affiliation: Department of Physical Therapy, University of Vermont, Burlington 05405, USA. breed@zoo.uvm.edu
authors.forename: B V
authors.initials: BV
authors.lastname: Reed
authors.forename: T
authors.initials: T
authors.lastname: Ashikaga
authors.forename: B C
authors.initials: BC
authors.lastname: Fleming
authors.forename: N J
authors.initials: NJ
authors.lastname: Zimny
mesh_terms: D000293:Adolescent; D000328:Adult; D003238:Connective Tissue / Q000502:physiology; D004311:Double-Blind Method; D005260:Female; D006358:Hot Temperature / Q000627:therapeutic use*; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D017888:Medial Collateral Ligament, Knee / Q000502:physiology*; D008875:Middle Aged; D015915:Motion Therapy, Continuous Passive; D014464:Ultrasonic Therapy