title: Obstacle crossing in Parkinson's disease: mediolateral sway of the centre of mass during level-ground walking and obstacle crossing.
abstract: BACKGROUND
  Falls are common in idiopathic Parkinson's disease (PD) and frequently occur when walking and crossing obstacles.
  
  
  OBJECTIVE
  To determine whether people with mild to moderately severe PD have abnormal centre of mass (CoM) motion in response to the perturbations of level-ground walking and obstacle crossing.
  
  
  METHODS
  Mediolateral excursion and velocity of the CoM were measured using three-dimensional motion analysis and force platforms in 20 people with mild to moderately severe PD at the peak dose of their PD medication, and 20 age and sex matched healthy control participants.
  
  
  RESULTS
  People with PD had greater sideways sway than healthy older adults when walking, particularly when walking over obstacles. People with PD also maintained their CoM more medial to their stance foot throughout the swing phase of gait compared to controls. The severity of motor symptoms in people with PD, measured using the UPDRS-III, was associated with faster sideways CoM motion but not increased CoM excursions.
  
  
  CONCLUSIONS
  Environmental hazards, such as ground-based obstacles, may accentuate postural instability in people with PD. Increased mediolateral sway might be due to impaired postural responses or kinematic compensations to increase foot clearance. Fall prevention programs could benefit from inclusion of components educating people with PD about the risks associated with obstacle crossing when walking.
authors: Institute for Ageing and Health, Clinical Ageing Research Unit, Newcastle University, Newcastle Upon Tyne NE4 5PL, United Kingdom. Electronic address: brook.galna@ncl.ac.uk.
authors: Brook
authors: B
authors: Galna
authors: Anna T
authors: AT
authors: Murphy
authors: Meg E
authors: ME
authors: Morris
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena; D005260:Female; D005684:Gait / Q000502:physiology; D020233:Gait Disorders, Neurologic / Q000209:etiology / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications / Q000503:physiopathology*; D004856:Postural Balance / Q000502:physiology*
keywords: Centre of mass; Gait; Obstacle crossing; Parkinson's disease