title: Effect of foot type on knee valgus, ground reaction force, and hip muscle activation in female soccer players.
abstract: BACKGROUND
  The purpose of this study was to determine the degree to which subtalar joint pronation resulting from a supple planus foot affects knee alignment, hip muscle activation and ground reaction force attenuation in female athletes during a broad jump-to-cut maneuver.
  
  
  METHODS
  Twelve National Collegiate Athletic Association (NCAA) Division II female soccer players (age=19.4±1.4 years, height=1.64±0.05 m, mass=64.10±4.8 kg) were identified as having either supple planus (SP) or rigid feet (RF). Participants completed three broad jump-to-cut trials onto a force plate while EMG and motion data were collected. Muscle activation levels (percentage of maximal voluntary contraction [%MVC]) in the gluteus maximus, gluteus medius, biceps femoris, and rectus femoris were calculated, and peak vertical and medial shear force, rate of loading, and valgus angle were collected for each trial.
  
  
  RESULTS
  Mann-Whitney U tests revealed no statistical significance between foot-type groups, however, effect size statistics revealed practical significance for between-group %MVC biceps femoris (d=1.107), %MVC gluteus maximus (d=1.069), and vertical ground reaction force (d=1.061).
  
  
  CONCLUSIONS
  Athletes with a SP foot type may experience decreased hip muscle activation associated with increased vertical ground reaction force during a broad jump-to-cut maneuver. This might result in reduced dynamic stability and neuromuscular control during deceleration, potentially increasing the risk of non-contact ACL injury in female soccer players.
authors.affiliation: Department of Kinesiology, West Chester University, West Chester, PA, USA - dstearne@wcupa.edu.
authors.forename: Meghan E
authors.initials: ME
authors.lastname: Rath
authors.forename: David J
authors.initials: DJ
authors.lastname: Stearne
authors.forename: Cameron R
authors.initials: CR
authors.lastname: Walker
authors.forename: Jaime C
authors.initials: JC
authors.lastname: Cox
mesh_terms: D000328:Adult; D056352:Athletes; D054874:Athletic Performance / Q000502:physiology*; D001696:Biomechanical Phenomena; D004576:Electromyography; D005260:Female; D005528:Foot; D006615:Hip / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D004856:Postural Balance / Q000502:physiology; D052097:Quadriceps Muscle; D016059:Range of Motion, Articular / Q000502:physiology; D012916:Soccer / Q000502:physiology