title: Knee-extension exercise's lack of immediate effect on maximal voluntary quadriceps torque and activation in individuals with anterior knee pain.
abstract: BACKGROUND
  Weight-bearing (WB) and non-weight-bearing (NWB) exercises are commonly used in rehabilitation programs for patients with anterior knee pain (AKP).
  
  
  OBJECTIVE
  To determine the immediate effects of isolated WB or NWB knee-extension exercises on quadriceps torque output and activation in individuals with AKP.
  
  
  METHODS
  A single-blind randomized controlled trial.
  
  
  METHODS
  Laboratory.
  
  
  METHODS
  30 subjects with self-reported AKP.
  
  
  METHODS
  Subjects performed a maximal voluntary isometric contraction (MVIC) of the quadriceps (knee at 90°). Maximal voluntary quadriceps activation was quantified using the central activation ratio (CAR): CAR = MVIC/(MVIC + superimposed burst torque). After baseline testing, subjects were randomized to 1 of 3 intervention groups: WB knee extension, NWB knee extension, or control. WB knee-extension exercise was performed as a sling-based exercise, and NWB knee-extension exercise was performed on the Biodex dynamometer. Exercises were performed in 3 sets of 5 repetitions at approximately 55% MVIC. Measurements were obtained at 4 times: baseline and immediately and 15 and 30 min postexercise.
  
  
  METHODS
  Quadriceps torque output (MVIC: N·m/Kg) and quadriceps activation (CAR).
  
  
  RESULTS
  No significant differences in the maximal voluntary quadriceps torque output (F2,27 = 0.592, P = .56) or activation (F2,27 = 0.069, P = .93) were observed among the 3 treatment groups.
  
  
  CONCLUSIONS
  WB and NWB knee-extension exercises did not acutely change quadriceps torque output or activation. It may be necessary to perform exercises over a number of sessions and incorporate other disinhibitory interventions (eg, cryotherapy) to observe acute changes in quadriceps torque and activation.
authors: Dept of Exercise Sciences, Brigham Young University, Provo, UT, USA.
authors: Jihong
authors: J
authors: Park
authors: Terry L
authors: TL
authors: Grindstaff
authors: Joe M
authors: JM
authors: Hart
authors: Jay N
authors: JN
authors: Hertel
authors: Christopher D
authors: CD
authors: Ingersoll
mesh_terms: D000293:Adolescent; D000328:Adult; D018771:Arthralgia / Q000503:physiopathology / Q000534:rehabilitation*; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D052097:Quadriceps Muscle / Q000502:physiology*; D055070:Resistance Training / Q000379:methods*; D016037:Single-Blind Method; D019415:Torque; D016474:Weight-Bearing / Q000502:physiology*; D055815:Young Adult