title: Lower limb muscle weakness predicts use of a multiple- versus single-step strategy to recover from forward loss of balance in older adults.
abstract: BACKGROUND
  Older adults compared with young adults have reduced strength and balance recovery ability. The purpose of the present study was to investigate whether age, sex, and/or lower limb strength predicted the stepping strategy used to recover from a forward loss of balance.
  
  
  METHODS
  Ninety-five, community-dwelling, older adults, aged 65-90 years, participated in the study. Loss of balance was induced by releasing participants from a static forward lean. Participants performed four trials at three initial lean magnitudes and were subsequently classified as using a single- or multiple-step strategy. Isometric strength of the ankle, knee, and hip joint flexors and extensors was assessed using a dynamometer.
  
  
  RESULTS
  Univariate logistic regression revealed that a unit (ie, 1% body weight [BW] × height) decrease in ankle plantar flexion, knee extension, or hip flexion strength was associated with 1.7-2.5 times increased odds of adopting a multiple-step strategy. Women also had greater odds of requiring a multiple-step recovery strategy at the two greatest lean magnitudes. Forward stepwise logistic regression revealed that hip flexor strength in particular was influential as it was the primary predictor included in the logistic regression models at 20% and 25% BW lean magnitudes.
  
  
  CONCLUSIONS
  Lower limb muscle weakness, especially of the hip flexors and knee extensors, was associated with increased odds of requiring multiple steps compared with single steps to recover from forward loss of balance across a range of initial lean magnitudes. Improved balance recovery ability might be achieved by targeting these muscle groups in falls prevention programs.
authors.affiliation: Centre for Musculoskeletal Research, Griffith Health Institute, Griffith University, Gold Coast Campus, Queensland, Australia 4222. c.carty@griffith.edu.au
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Carty
authors.forename: Rod S
authors.initials: RS
authors.lastname: Barrett
authors.forename: Neil J
authors.initials: NJ
authors.lastname: Cronin
authors.forename: Glen A
authors.initials: GA
authors.lastname: Lichtwark
authors.forename: Peter M
authors.initials: PM
authors.lastname: Mills
mesh_terms: D000058:Accidental Falls / Q000517:prevention & control*; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D000704:Analysis of Variance; D005260:Female; D006801:Humans; D016015:Logistic Models; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D009068:Movement; D018908:Muscle Weakness / Q000150:complications / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000502:physiology; D016017:Odds Ratio; D004856:Postural Balance / Q000502:physiology*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011930:Reaction Time; D018570:Risk Assessment; D012678:Sensation Disorders / Q000150:complications*; D012737:Sex Factors