title: Walking performance and muscle strength in the later stage poststroke: a nonlinear relationship.
abstract: OBJECTIVE
  To evaluate the relation between muscle strength in the lower extremities and walking performance (speed and distance) in subjects in the later stage poststroke and to compare this with normative data.
  
  
  METHODS
  A cross-sectional observational study.
  
  
  METHODS
  University hospital department.
  
  
  METHODS
  Subjects poststroke (n=41; 31 men, 10 women) with a mean age of 59±5.8 years and a time from stroke onset of 52±36 months were evaluated. An urban sample (n=144) of 40- to 79-year-olds (69 men, 75 women) formed the healthy reference group.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  Muscle strength in the lower extremities was measured with an isokinetic dynamometer and combined into a strength index. Values for the 30-meter walk test for self-selected and maximum speed and the 6-minute walk test were measured. A nonlinear regression model was used.
  
  
  RESULTS
  The average strength index was 730±309 in the subjects after stroke compared with 1112±362 in the healthy group. A nonlinear relation between walking performance and muscle strength was evident. The model explained 37% of the variance in self-selected speed in the stroke group and 20% in the healthy group, and 63% and 38%, respectively, in the maximum walking speed. For the 6-minute walk test, the model explained 44% of the variance in the stroke group.
  
  
  CONCLUSIONS
  Subjects in the later stage poststroke were weaker than the healthy reference group, and their weakness was associated with walking performance. At the same strength index, subjects walked at lower speeds and shorter distances after stroke, indicating that there are multiple impairments that affect walking ability. Treatments focused on increasing muscle strength thus continue to hold promise.
authors.affiliation: Section of Clinical Neuroscience and Rehabilitation Medicine, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. cristiane.carvalho@neuro.gu.se
authors.forename: Cristiane
authors.initials: C
authors.lastname: Carvalho
authors.forename: Katharina S
authors.initials: KS
authors.lastname: Sunnerhagen
authors.forename: Carin
authors.initials: C
authors.lastname: Willén
mesh_terms: D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D005080:Exercise Test; D005260:Female; D006801:Humans; D035002:Lower Extremity / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength; D053581:Muscle Strength Dynamometer; D017711:Nonlinear Dynamics; D020521:Stroke / Q000150:complications / Q000503:physiopathology*; D013647:Task Performance and Analysis; D013997:Time Factors; D016138:Walking / Q000502:physiology*