title: Activation of the VMO and VL during dynamic mini-squat exercises with and without isometric hip adduction.
abstract: OBJECTIVE
  the purpose of this study was to compare vastus medialis obliquus (VMO) and vastus lateralis (VL) activity while performing a mini-squat with and without isometric hip adduction.
  
  
  METHODS
  a repeated measures within subjects design was used. Subjects performed two sets of three repetitions of a traditional mini-squat and a mini-squat with concurrent hip adduction (squeeze).
  
  
  METHODS
  20 recreationally active subjects (10 men, 10 women age=28.10+/-5.91 years, height=170.94+/-11.03 cm, mass=72.32+/-16.66 kg) with no history of patellofemoral pain (PFP), quadriceps injury, or other knee injury participated in the study.
  
  
  METHODS
  the EMG signal of the VMO and VL was recorded bilaterally during both exercises. EMG data were normalized to the maximal voluntary isometric contraction (MVIC) of the quadriceps produced during seated, isometric knee extension.
  
  
  RESULTS
  results of repeated measures ANOVA's revealed that the squeeze squat produced significantly greater VMO and VL activity than the traditional squat (p=0.02). For both the traditional and squeeze squats, intrasession reliability from the first to the second set was calculated using intraclass correlation coefficient (ICC) formula (3:1) bilaterally for both the VMO and the VL. All ICC values were greater than 0.9.
  
  
  CONCLUSIONS
  combining isometric hip adduction with a mini-squat exercise significantly increases the activity of the quadriceps. Performing mini-squats with isometric hip adduction will be beneficial to patellofemoral patients as they increase quadriceps activity, however, based on our data we cannot conclude that this exercise preferentially recruits the VMO. Further research is needed to determine the exact mechanism by which quadriceps function is altered.
authors.affiliation: Department of Kinesiology, Pennsylvania State University, 266 Recreation Hall, University Park, PA 16802, USA. jee128@psu.edu
authors.forename: J E
authors.initials: JE
authors.lastname: Earl
authors.forename: R J
authors.initials: RJ
authors.lastname: Schmitz
authors.forename: B L
authors.initials: BL
authors.lastname: Arnold
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D004576:Electromyography; D015444:Exercise / Q000502:physiology*; D005260:Female; D006621:Hip Joint / Q000502:physiology*; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*