title: Lower limb muscle moments and power during recovery from forward loss of balance in male and female single and multiple steppers.
abstract: BACKGROUND
  Studying recovery responses to loss of balance may help to explain why older adults are susceptible to falls. The purpose of the present study was to assess whether male and female older adults, that use a single or multiple step recovery strategy, differ in the proportion of lower limb strength used and power produced during the stepping phase of balance recovery.
  
  
  METHODS
  Eighty-four community-dwelling older adults (47 men, 37 women) participated in the study. Isometric strength of the ankle, knee and hip joint flexors and extensors was assessed using a dynamometer. Loss of balance was induced by releasing participants from a static forward lean (4 trials at each of 3 forward lean angles). Participants were instructed to recover with a single step and were subsequently classified as using a single or multiple step recovery strategy for each trial.
  
  
  RESULTS
  (1) Females were weaker than males and the proportion of females that were able to recover with a single step were lower than for males at each lean magnitude. (2) Multiple compared to single steppers used a significantly higher proportion of their hip extension strength and produced less knee and ankle joint peak power during stepping, at the intermediate lean angle.
  
  
  CONCLUSIONS
  Strength deficits in female compared to male participants may explain why a lower proportion of female participants were able to recover with a single step. The inability to generate sufficient power in the stepping limb appears to be a limiting factor in single step recovery from forward loss of balance.
authors.affiliation: Centre for Musculoskeletal Research, Griffith Health Institute & School of Rehabilitation Sciences, Griffith University, Queensland, Australia. c.carty@griffith.edu.au
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Carty
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
authors.forename: Rod S
authors.initials: RS
authors.lastname: Barrett
mesh_terms: D000058:Accidental Falls; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D000843:Ankle Joint / Q000502:physiology; D005260:Female; D006621:Hip Joint / Q000502:physiology; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D053581:Muscle Strength Dynamometer; D018908:Muscle Weakness / Q000503:physiopathology; D004856:Postural Balance / Q000502:physiology*; D012307:Risk Factors; D012737:Sex Factors