title: Hip- and trunk-muscle activation patterns during perturbed gait.
abstract: BACKGROUND
  Selected muscles in the kinetic chain may help explain the body's ability to avert injury during unexpected perturbation.
  
  
  OBJECTIVE
  To determine the activation of the ipsilateral rectus femoris (RF), gluteus maximus (MA), gluteus medius (ME), and contralateral external obliques (EO) during normal and perturbed gait.
  
  
  METHODS
  Single-factor, repeated measures.
  
  
  METHODS
  University research laboratory.
  
  
  METHODS
  32 physically active, college-age subjects.
  
  
  METHODS
  Subjects walked a total of 20 trials the length of a 6.1-m custom runway capable of releasing either side into 30° of unexpected inversion. During 5 trials, the platform released into inversion.
  
  
  METHODS
  Average, peak, and time to peak EMG were analyzed across the 4 muscles, and comparisons were made between the walking trials and perturbed trials.
  
  
  RESULTS
  Significantly higher average and peak muscle activity were noted for the perturbed condition for RF, MA, and EO. Time to peak muscle activity was faster during the perturbed condition for the EO.
  
  
  CONCLUSIONS
  Rapid contractions of selected postural muscles in the kinetic chain help explain the body's reaction to unexpected perturbation.
authors.affiliation: School of Kinesiology and Recreation, Illinois State University, Normal, IL, USA.
authors.forename: Justin M
authors.initials: JM
authors.lastname: Stanek
authors.forename: Todd A
authors.initials: TA
authors.lastname: McLoda
authors.forename: Val J
authors.initials: VJ
authors.lastname: Csiszer
authors.forename: A J
authors.initials: AJ
authors.lastname: Hansen
mesh_terms: D000005:Abdomen / Q000502:physiology; D000704:Analysis of Variance; D004576:Electromyography; D005260:Female; D005684:Gait / Q000502:physiology*; D006615:Hip / Q000502:physiology; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D016138:Walking / Q000502:physiology; D055815:Young Adult