title: Role of Hip Abductor Muscle Composition and Torque in Protective Stepping for Lateral Balance Recovery in Older Adults.
abstract: To examine differences in hip abductor strength and composition between older adults who primarily use medial step versus cross-step recovery strategies to lateral balance perturbations.
  
  
  
  Cross-sectional.
  
  
  
  University research laboratory.
  
  
  
  Community-dwelling older adults (N=40) divided into medial steppers (n=14) and cross-steppers (n=26) based on the first step of balance recovery after a lateral balance perturbation.
  
  
  
  Not applicable.
  
  
  
  Computed tomography scans to quantify lean tissue and intramuscular adipose tissue (IMAT) areas in the hip abductor, hip abductor isokinetic torque, and first step length.
  
  
  
  Medial steppers took medial steps in 71.1% of trials versus 4.6% of trials with cross-steps. The cross-steppers when compared with medial steppers, had lower hip abductor IMAT (24.7±0.7% vs 29.9±2.8%; P<.05), greater abductor torque (63.3±3.6Nm vs 48.4±4.1Nm; P<.01), and greater normalized first step length (.75±.03 vs .43±.08; P<.001). There was no difference in hip abductor lean tissue between the groups (P>.05).
  
  
  
  Our findings suggest that older adults who initially use a medial step to recover lateral balance have lower hip abductor torque and may be less able to execute a biomechanically more stable cross-step. This may be related to increased IMAT levels. Assessments and interventions for enhancing balance and decreasing fall risk should take the role of the hip abductor into account.
authors.affiliation: Department of Veterans Affairs and Veterans Affairs Medical Center Baltimore, Geriatric Research, Education, and Clinical Center (GRECC), Baltimore, MD; Department of Physical Therapy and Rehabilitation Science, University of Maryland School of Medicine, Baltimore, MD.
authors.forename: Odessa
authors.initials: O
authors.lastname: Addison
authors.affiliation: Department of Physical Therapy and Rehabilitation Science, University of Maryland School of Medicine, Baltimore, MD.
authors.forename: Mario
authors.initials: M
authors.lastname: Inacio
authors.affiliation: Department of Physical Therapy and Rehabilitation Science, University of Maryland School of Medicine, Baltimore, MD.
authors.forename: Woei-Nan
authors.initials: WN
authors.lastname: Bair
authors.affiliation: Department of Veterans Affairs and Veterans Affairs Medical Center Baltimore, Geriatric Research, Education, and Clinical Center (GRECC), Baltimore, MD; Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD.
authors.forename: Brock A
authors.initials: BA
authors.lastname: Beamer
authors.affiliation: Department of Veterans Affairs and Veterans Affairs Medical Center Baltimore, Geriatric Research, Education, and Clinical Center (GRECC), Baltimore, MD; Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD.
authors.forename: Alice S
authors.initials: AS
authors.lastname: Ryan
authors.affiliation: Department of Physical Therapy and Rehabilitation Science, University of Maryland School of Medicine, Baltimore, MD. Electronic address: mrogers@som.umaryland.edu.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Rogers
mesh_terms: D000273:Adipose Tissue / Q000502:physiology*; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005260:Female; D006621:Hip Joint / Q000502:physiology*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D004856:Postural Balance / Q000502:physiology*; D014057:Tomography, X-Ray Computed
keywords: Hip; Muscle strength; Muscle, skeletal; Postural balance; Rehabilitation