title: Symmetry of corticomotor input to plantarflexors influences the propulsive strategy used to increase walking speed post-stroke.
abstract: OBJECTIVE
  A deficit in paretic limb propulsion has been identified as a major biomechanical factor limiting walking speed after stroke. The purpose of this study was to determine the influence of corticomotor symmetry between paretic and nonparetic plantarflexors on the propulsive strategy used to increase walking speed.
  
  
  METHODS
  Twenty-three participants with post-stroke hemiparesis underwent transcranial magnetic stimulation and biomechanical testing at their self-selected and fastest walking speeds. Plantarflexor corticomotor symmetry (CS(PF)) was calculated as a ratio of the average paretic versus nonparetic soleus motor evoked potential amplitude. The ratio of the paretic and nonparetic peak ankle plantarflexion moments (PF(sym)) was calculated at each speed.
  
  
  RESULTS
  CS(PF) predicted the ΔPF(sym) from self-selected and fastest speeds (R(2)=.629, F(1,21)=35.56, p<.001). An interaction between CS(PF) and ΔPF(sym) (β=.596, p=.04) was observed when predicting Δspeed ((adj)R(2)=.772, F(3,19)=20.48, p<.001). Specifically, the ΔPF(sym) with speed modulation was positively related to the Δspeed (p=.03) in those with greater CS(PF), but was not related in those with poor CS(PF) (p=.30).
  
  
  CONCLUSIONS
  Symmetry of the corticomotor input to the plantarflexors influences the propulsive strategy used to increase post-stroke walking speed.
  
  
  CONCLUSIONS
  Rehabilitation strategies that promote corticomotor symmetry may positively influence gait mechanics and enhance post-stroke walking function.
authors.affiliation: Department of Physical Therapy, University of Delaware, Newark, DE 19713, USA; Graduate Program in Biomechanics and Movement Science, University of Delaware, Newark, DE 19713, USA. Electronic address: palmerja@udel.edu.
authors.forename: Jacqueline A
authors.initials: JA
authors.lastname: Palmer
authors.affiliation: Graduate Program in Biomechanics and Movement Science, University of Delaware, Newark, DE 19713, USA.
authors.forename: HaoYuan
authors.initials: H
authors.lastname: Hsiao
authors.affiliation: Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA; Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Louis N
authors.initials: LN
authors.lastname: Awad
authors.affiliation: Department of Physical Therapy, University of Delaware, Newark, DE 19713, USA; Graduate Program in Biomechanics and Movement Science, University of Delaware, Newark, DE 19713, USA.
authors.forename: Stuart A
authors.initials: SA
authors.lastname: Binder-Macleod
mesh_terms: D000368:Aged; D000843:Ankle Joint / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation* / Q000502:physiology*; D010291:Paresis / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D020521:Stroke / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation / Q000379:methods; D016138:Walking / Q000502:physiology*
keywords: Asymmetry; Gait; Propulsion; Stroke; Transcranial magnetic stimulation