title: Resisted Side Stepping: The Effect of Posture on Hip Abductor Muscle Activation.
abstract: METHODS
  Controlled laboratory study, repeated-measures design.
  
  
  OBJECTIVE
  To compare hip abductor muscle activity and hip and knee joint kinematics in the moving limb to the stance limb during resisted side stepping, and to determine whether muscle activity was affected by the posture (upright standing versus squat) used to perform the exercise.
  
  
  BACKGROUND
  Hip abductor weakness has been associated with a variety of lower extremity injuries. Resisted side stepping is often used as an exercise to increase strength and endurance of the hip abductors. Exercise prescription would benefit from knowing the relative muscle activity level generated in each limb and for different postures during the side-stepping exercise.
  
  
  METHODS
  Twenty-four healthy adults participated in this study. Kinematics and surface electromyographic data from the gluteus maximus, gluteus medius, and tensor fascia lata were collected as participants performed side stepping with a resistive band around the ankle, while maintaining each of 2 postures: (1) upright standing and (2) squat.
  
  
  RESULTS
  Mean normalized electromyographic signal amplitude of the gluteus maximus, gluteus medius, and tensor fascia lata was higher in the stance limb than in the moving limb (P≤.001). Gluteal muscle activity was higher, whereas tensor fascia lata muscle activity was lower, in the squat posture compared to the upright standing posture (P<.001). Hip abduction excursion was greater in the stance limb than in the moving limb (P<.001).
  
  
  CONCLUSIONS
  The 3 hip abductor muscles respond differently to the posture variations of the side-stepping exercise in healthy individuals. When prescribing resisted side-stepping exercises, therapists should consider the differences in hip abductor activation across limbs and variations in trunk posture.
authors.affiliation: Physical Therapist Assistant Program, Northland Community and Technical College, East Grand Forks, MN.
authors.forename: Justin W
authors.initials: JW
authors.lastname: Berry
authors.forename: Theresa S
authors.initials: TS
authors.lastname: Lee
authors.forename: Hanna D
authors.initials: HD
authors.lastname: Foley
authors.forename: Cara L
authors.initials: CL
authors.lastname: Lewis
mesh_terms: D001696:Biomechanical Phenomena; D004576:Electromyography; D005260:Female; D006621:Hip Joint / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D055070:Resistance Training; D055815:Young Adult
keywords: electromyography; gluteus maximus; gluteus medius; strengthening; tensor fascia lata