title: Relationship between hip abductor rate of force development and mediolateral stability in older adults.
abstract: OBJECTIVE
  To examine the relationship between hip abductor rate of force development (RFD) and performance of reactive and voluntary balance tasks in older adults.
  
  
  METHODS
  Descriptive study using correlation and regression analyses.
  
  
  METHODS
  University research laboratory.
  
  
  METHODS
  A volunteer sample of 30 community-dwelling men and women over the age of 65 years.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  Measures of hip abductor RFD, center of pressure (COP) displacement during compensatory stepping, and scores on 1-leg standing (OLS), and tandem gait tests. Hip abductor RFD was defined as the time required to go from 10% of maximum force to 60% of maximum force (10%-60% RFD) or to 90% of maximum force (10%-90% RFD).
  
  
  RESULTS
  Hip abductor RFD did not correlate with COP displacement during compensatory stepping, but did correlate significantly with OLS and tandem gait variables (P<.05). In predicting OLS scores, age (beta=-.485, P<.05) and 10% to 60% RFD (beta=-.354, P<.05) were significant predictors. In predicting tandem gait scores, 10% to 90% RFD (beta=.384, P<.05) was the only significant predictor in the final regression model.
  
  
  CONCLUSIONS
  Hip abductor RFD, tested under voluntary conditions, correlated with performance of clinical tests that challenge lateral stability. Our results support the idea that voluntary and reactive balance tasks involve different types of neuromuscular control.
authors.affiliation: Center for Human Movement Science, Department of Allied Health Sciences, School of Medicine, University of North Carolina, Chapel Hill, NC 27599-7135, USA.
authors.forename: Shuo-Hsiu J
authors.initials: SH
authors.lastname: Chang
authors.forename: Vicki S
authors.initials: VS
authors.lastname: Mercer
authors.forename: Carol A
authors.initials: CA
authors.lastname: Giuliani
authors.forename: Philip D
authors.initials: PD
authors.lastname: Sloane
mesh_terms: D000054:Acceleration; D000058:Accidental Falls / Q000517:prevention & control; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D015331:Cohort Studies; D005260:Female; D005684:Gait / Q000502:physiology*; D015577:Geriatric Assessment; D006621:Hip Joint / Q000502:physiology*; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D004856:Postural Balance / Q000502:physiology*; D011336:Probability; D016059:Range of Motion, Articular / Q000502:physiology*; D012044:Regression Analysis; D012307:Risk Factors