title: The variable component of lateral body sway during walking in young and older humans.
abstract: BACKGROUND
  Because sideways falls are common in elderly persons, we devised a method to measure variable lateral movements of the thorax with respect to foot position during normal walking.
  
  
  METHODS
  Movements of the ankles and shoulders were measured during walking a distance of 9 m. Two age groups were studied: young (n = 17, 6 male, mean age 27.3 years) and older (n = 21, 13 male, mean age 72.7 years) people. During walking, the path followed in the horizontal plane by the midpoint between the two shoulders was compared to the line connecting successive positions of the ankles during stance. Lateral deviations between these two paths were divided into a regular component (average of about 30 strides) and a variable component (the difference between the deviation during each stride and the average). Lateral sway was also observed while standing with eyes open for 1 minute.
  
  
  RESULTS
  The older group had more lateral movement during walking in the variable component (p =.006) and a nonsignificant trend (p =.054) in the same direction in the regular component. Eight of the older participants had a value for the variable component greater than the 95% confidence limit for the young participants. Only two of the older participants had a standing sway outside the confidence limit for the young participants. The variable component was associated with variability in stride width.
  
  
  CONCLUSIONS
  The variable component of lateral sway during walking provides good discrimination between age groups, as does variability in step width. It remains to be seen whether these variables are different in fallers and nonfallers.
authors.affiliation: Centre for Applied Biomedical Research, School of Biomedical Sciences, Kings College London, Shepherds House, Guys Campus, London SE1 1UL, UK.
authors.forename: Roger C
authors.initials: RC
authors.lastname: Woledge
authors.forename: Deirdre B
authors.initials: DB
authors.lastname: Birtles
authors.forename: Di J
authors.initials: DJ
authors.lastname: Newham
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D011187:Posture; D013909:Thorax / Q000502:physiology*; D016138:Walking