title: Lateral reach: a clinical measure of medio-lateral postural stability.
abstract: OBJECTIVE
  Medio-lateral postural instability has recently been identified as a risk factor for falls in the elderly community-dwelling population. However, few clinical tests involve challenges to stability limits in the medio-lateral direction. A lateral reach test was thus developed. Preliminary evaluation of the symmetry, accuracy, test-retest repeatability, and construct validity of the lateral reach test was undertaken to ensure its validity and repeatability prior to clinical application.
  
  
  METHODS
  Sixty healthy older female subjects (aged 72.5 +/- 5 years) participated in this study which involved two tasks. The first was the clinical test: a maximal lateral reach to the right and left, recorded by a clinical measure (observation of hand excursion) and a laboratory measure (3D analysis of hand marker excursion). The second was the recording of centre of pressure (COP) stability limits in the lateral direction by use of a dual force platform system. Eighteen subjects returned for repeatability testing.
  
  
  RESULTS
  No significant differences in the measures were found between the sides. Lateral reach as measured by the clinical measure was significantly (p < 0.05) correlated with both the laboratory measure of reach (r = 0.650) and with COP stability limits (r = 0.331). The clinical measure of reach was not significantly different (p > 0.01) from the laboratory measure. High test-retest repeatability (r > 0.94) was found for all measures.
  
  
  CONCLUSIONS
  The clinical lateral reach test was found to be an accurate measure of lateral reach ability. As it was significantly correlated with COP excursion it was deemed a valid indicator of lateral stability limits. In addition, the lateral reach test had high test-retest repeatability and was symmetrical between the sides. These promising results support both it's use where a clinical indicator of medio-lateral postural stability is desired and further investigation of the lateral reach test in clinical populations.
authors.affiliation: Department of Physiotherapy, University of Queensland, Australia. sbrauer@uoneuro.uoregon.edu
authors.forename: S
authors.initials: S
authors.lastname: Brauer
authors.forename: Y
authors.initials: Y
authors.lastname: Burns
authors.forename: P
authors.initials: P
authors.lastname: Galley
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis* / Q000503:physiopathology; D004856:Postural Balance; D011187:Posture; D011237:Predictive Value of Tests; D013131:Spine / Q000502:physiology*; D013647:Task Performance and Analysis