title: Motor Planning for Loading During Gait in Subacute Stroke.
abstract: OBJECTIVE
  To determine the characteristics of motor planning surrounding initial contact during gait through examination of thigh muscle timing, amplitude, and co-contraction of the paretic and nonparetic limbs in people poststroke, and to investigate whether muscle timing, amplitude, and clinical performance measures of balance and mobility differ based on the level of co-contraction.
  
  
  METHODS
  Observational study.
  
  
  METHODS
  University-based research laboratory.
  
  
  METHODS
  Individuals (n=27) in the subacute phase after stroke and healthy controls (n=8) (N=35).
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  Timing (onset and offset) and normalized amplitude (percent electromyography maximum) of the biceps femoris (BF) and rectus femoris (RF) muscles were measured during terminal swing and early stance. A co-contraction index (CCI) was calculated for the BF and RF muscle activity. Individuals with CCI values equal to or below the mean of the healthy group were in the low CCI group, whereas those with values above the mean were in the high CCI group. Functional balance and mobility evaluation used the Community Balance and Mobility Scale (CB&M).
  
  
  RESULTS
  For the paretic and nonparetic limbs, measures of timing, amplitude, and co-contraction were similar for both limbs. Compared with the healthy group, the high CCI group had lower CB&M scores, longer durations, and higher levels of RF and BF muscle activity, whereas the low CCI group had electromyographic measures statistically similar to healthy controls.
  
  
  CONCLUSIONS
  The motor control of gait after subacute stroke is characterized by symmetry of timing and amplitude of muscle recruitment at the knee. High co-contraction levels surrounding the knee were associated with lower functional balance and mobility. These findings suggest a compensatory strategy of increased co-contraction in those with more impairment while maintaining symmetry of lower-limb biomechanics between limbs.
authors.affiliation: Department of Physical Therapy, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Sue
authors.initials: S
authors.lastname: Peters
authors.affiliation: Department of Physical Therapy, University of British Columbia, Vancouver, BC, Canada.
authors.forename: S Jayne
authors.initials: SJ
authors.lastname: Garland
authors.affiliation: Department of Physical Therapy, University of British Columbia, Vancouver, BC, Canada; Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada.
authors.forename: Kimberly J
authors.initials: KJ
authors.lastname: Miller
authors.affiliation: Department of Physical Therapy, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Cochrane
authors.affiliation: Department of Physical Therapy, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Tanya D
authors.initials: TD
authors.lastname: Ivanova
authors.affiliation: Department of Physical Therapy, University of British Columbia, Vancouver, BC, Canada. Electronic address: michael.hunt@ubc.ca.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Hunt
mesh_terms: D000368:Aged; D001132:Arm / Q000503:physiopathology; D016022:Case-Control Studies; D004576:Electromyography; D005260:Female; D005684:Gait / Q000502:physiology*; D020233:Gait Disorders, Neurologic / Q000209:etiology / Q000503:physiopathology*; D006801:Humans; D035002:Lower Extremity / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D051346:Mobility Limitation; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology*; D010291:Paresis / Q000209:etiology / Q000503:physiopathology; D004856:Postural Balance; D052097:Quadriceps Muscle / Q000503:physiopathology; D020521:Stroke / Q000150:complications / Q000503:physiopathology*
keywords: Gait; Knee; Muscles; Rehabilitation; Stroke