title: The single-leg-stance test in Parkinson's disease.
abstract: BACKGROUND
  Timed single-leg-stance test (SLST) is widely used to assess postural control in the elderly. In Parkinson's disease (PD), it has been shown that an SLST around 10 seconds or below may be a sensitive indicator of future falls. However, despite its role in fall risk, whether SLST times around 10 seconds marks a clinically important stage of disease progression has largely remained unexplored.
  
  
  METHODS
  A cross-sectional study where 27 people with PD were recruited and instructed to undertake timed SLST for both legs was conducted. Disease motor impairment was assessed with the Unified Parkinson's Disease Rating Scale Part 3 (UPDRS-III).
  
  
  RESULTS
  This study found that: 1) the SLST in people with PD shows good test-retest reliability; 2) SLST values can be attributed to two non-overlapping clusters: a low (10.4 ± 6.3 seconds) and a high (47.6 ± 11.7 seconds) value SLST group; 3) only the low value SLST group can be considered abnormal when age-matched normative SLST data are taken into account for comparison; and 4) lower UPDRS-III motor performance, and the bradykinesia sub-score in particular, are only associated with the low SLST group.
  
  
  CONCLUSIONS
  These results lend further support that a low SLST time around 10 seconds marks a clinically important stage of disease progression with significant worsening of postural stability in PD.
authors.affiliation: Department of Clinical Neurosciences, Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary, Calgary, AB, Canada.
authors.forename: Taylor
authors.initials: T
authors.lastname: Chomiak
authors.affiliation: Department of Clinical Neurosciences, Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary, Calgary, AB, Canada.
authors.forename: Fernando Vieira
authors.initials: FV
authors.lastname: Pereira
authors.affiliation: Department of Clinical Neurosciences, Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary, Calgary, AB, Canada.
authors.forename: Bin
authors.initials: B
authors.lastname: Hu
keywords: Balance; Bradykinesia; Leg; Parkinson’s disease; Reliability; Single; Stance; Test; Unipedal