title: Immediate effects of transcutaneous electrical nerve stimulation and focal knee joint cooling on quadriceps activation.
abstract: OBJECTIVE
  To determine whether transcutaneous electrical nerve stimulation (TENS) and focal knee joint cooling will affect the quadriceps central activation ratio (CAR) in patients with tibiofemoral osteoarthritis.
  
  
  METHODS
  Thirty-three participants with diagnosed tibiofemoral osteoarthritis were randomly allocated to the 45-min TENS treatment (six males and four females, 56 +/- 10.1 yr, 174.11 +/- 10.78 cm, 89.34 +/- 21.3 kg), the 20-min focal knee joint cooling treatment (six males and five females, 58 +/- 8.4 yr, 176.41 +/- 8.29 cm, 83.18 +/- 17.97 kg), or the control group (five males and seven females, 54 +/- 9.9 yr, 166.37 +/- 13.07 cm, 92.14 +/- 25.37 kg). Volitional quadriceps activation, maximal voluntary isometric contraction, and subjective pain measurements were conducted at baseline and at 20, 30, and 45 min. The 20-min focal knee joint cooling intervention consisted of two 1.5-L ice bags to the anterior and posterior aspects of the knee. The TENS group received 45 min of a sensory, biphasic square wave stimulation (150-mus phase duration and 150 pps) from four 2 x 2-inch electrodes positioned around the patella.
  
  
  RESULTS
  : TENS resulted in a significantly higher percent change in CAR scores compared with control at 20 min (6.4 +/- 4.8 vs -3.5 +/- 8, P = 0.006), 30 min (9.7 +/- 10.16 vs -1 +/- 7.9, P = 0.025), and 45 min (11.25 +/- 6.96 vs 0.81 +/- 9.4, P = 0.029). Focal knee joint cooling resulted in significantly higher percent change scores compared with the control group at 20 min (5.75 +/- 7.25 vs -3.5 +/- 8, P = 0.009) and trended to be higher at 45 min (9.06 +/- 9.63 vs 0.81 +/- 9.4, P = 0.098). No significant differences in percent change for CAR were found between the TENS and the focal knee joint cooling group.
  
  
  CONCLUSIONS
  Both TENS and focal knee joint cooling increased the quadriceps CAR immediately after application in participants with tibiofemoral osteoarthritis.
authors.affiliation: Exercise and Sport Injury Laboratory, University of Virginia, Charlottesville, VA, USA.
authors.forename: Brian G
authors.initials: BG
authors.lastname: Pietrosimone
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Hart
authors.forename: Susan A
authors.initials: SA
authors.lastname: Saliba
authors.forename: Jay
authors.initials: J
authors.lastname: Hertel
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Ingersoll
mesh_terms: D000704:Analysis of Variance; D003080:Cold Temperature; D016001:Confidence Intervals; D017679:Cryotherapy; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D007719:Knee Joint; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons; D020370:Osteoarthritis, Knee; D010147:Pain Measurement; D052097:Quadriceps Muscle / Q000294:innervation*; D016037:Single-Blind Method; D013997:Time Factors; D004561:Transcutaneous Electric Nerve Stimulation