title: Impairments in systems underlying control of balance in COPD.
abstract: BACKGROUND
  Although balance deficits are increasingly recognized in COPD, little is known regarding the disordered subcomponents underlying the control of balance. We aimed to determine the specific components of balance that are impaired in COPD and to investigate the association among balance, peripheral muscle strength, and physical activity.
  
  
  METHODS
  Balance, physical activity, and lower extremity muscle strength were assessed in 37 patients with COPD and 20 age-matched healthy control subjects using the Balance Evaluation Systems Test (BESTest), the Physical Activity Scale for the Elderly, and an isokinetic dynamometer, respectively. A subset of subjects (20 patients with COPD and 20 control subjects) underwent a second testing session in which postural perturbations were delivered using a lean-and-release system.
  
  
  RESULTS
  Subjects with COPD (age, 71 ± 7 years; FEV(1), 39% ± 16% predicted) exhibited significantly lower scores than did control subjects (age, 67 ± 9 years) on all of the BESTest subscales (all P < .001). In response to anterior perturbations, subjects with COPD showed a longer time to foot-off (P = .027) and foot contact (P = .018), and a longer duration anticipatory phase (P = .008) compared with control subjects. Muscle strength (P = .008) and self-reported physical activity (P = .033) explained 35% of the variance in balance in subjects with COPD.
  
  
  CONCLUSIONS
  Individuals with COPD exhibit impairments in all balance subcomponents and demonstrate slower reaction times in response to perturbations. Deficits in balance are associated with reduced physical activity levels and skeletal muscle weakness.
authors: Graduate Department of Rehabilitation Science, University of Toronto, Toronto, ON, Canada; Respiratory Medicine, West Park Healthcare Centre, Toronto, ON, Canada.
authors: Marla K
authors: MK
authors: Beauchamp
authors: Department of Physical Therapy, University of Toronto, Toronto, ON, Canada; Toronto Rehabilitation Institute, Toronto, ON, Canada.
authors: Kathryn M
authors: KM
authors: Sibley
authors: Graduate Department of Rehabilitation Science, University of Toronto, Toronto, ON, Canada; Toronto Rehabilitation Institute, Toronto, ON, Canada.
authors: Bimal
authors: B
authors: Lakhani
authors: Respiratory Medicine, West Park Healthcare Centre, Toronto, ON, Canada.
authors: Julia
authors: J
authors: Romano
authors: Department of Physical Therapy, University of Toronto, Toronto, ON, Canada; Respiratory Medicine, West Park Healthcare Centre, Toronto, ON, Canada.
authors: Sunita
authors: S
authors: Mathur
authors: Department of Physical Therapy, University of Toronto, Toronto, ON, Canada; Respiratory Medicine, West Park Healthcare Centre, Toronto, ON, Canada.
authors: Roger S
authors: RS
authors: Goldstein
authors: Graduate Department of Rehabilitation Science, University of Toronto, Toronto, ON, Canada; Department of Physical Therapy, University of Toronto, Toronto, ON, Canada; Respiratory Medicine, West Park Healthcare Centre, Toronto, ON, Canada; Toronto Rehabilitation Institute, Toronto, ON, Canada. Electronic address: dina.brooks@utoronto.ca.
authors: Dina
authors: D
authors: Brooks
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D005260:Female; D015577:Geriatric Assessment; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology; D053580:Muscle Strength / Q000502:physiology; D004856:Postural Balance / Q000502:physiology*; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D012044:Regression Analysis; D013147:Spirometry