title: Loading and knee flexion after stroke: Less does not equal more.
abstract: It is believed that force feedback can modulate lower extremity extensor activity during gait. The purpose of this research was to determine the role of limb loading on knee extensor excitability during the late stance/early swing phase of gait in persons post-stroke. Ten subjects with chronic hemiparesis post-stroke participated in (1) seated isolated quadriceps reflex testing with ankle loads of 0-0.4Nm/kg and (2) gait analysis on a treadmill with 0%, 20% or 40% body weight support. Muscle reflex responses were recorded from vastus lateralis (VL), rectus femoris (RF), and vastus medialis (VM) during seated testing. Knee kinematics and quadriceps activity during late stance/early swing phase of gait were compared across loading conditions. Although isolated loading of the ankle plantarflexors at 0.2Nm/kg reduced VM prolonged response (p=0.04), loading did not alter any other measure of quadriceps excitability (all p>0.08). During gait, the use of BWS did not influence knee kinematics (p=0.18) or muscle activity (all p>0.17) during late stance/early swing phase. This information suggests that load sensed at the ankle has minimal effect on the ipsilateral quadriceps of individuals post-stroke during late stance. It appears that adjusting limb loading during rehabilitation may not be an effective tool to address stiff-knee gait following stroke.
authors.affiliation: Division of Physical Therapy, Department of Allied Health Sciences, University of North Carolina at Chapel Hill, USA; Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Mary
authors.initials: M
authors.lastname: Murray
authors.affiliation: Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, USA; Teleflex Medical, Durham, NC, USA.
authors.forename: Amy
authors.initials: A
authors.lastname: Hardee
authors.affiliation: Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, USA.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Goldberg
authors.affiliation: Division of Physical Therapy, Department of Allied Health Sciences, University of North Carolina at Chapel Hill, USA; Human Movement Science Program, University of North Carolina at Chapel Hill, USA. Electronic address: mlewek@med.unc.edu.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Lewek
mesh_terms: D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D002908:Chronic Disease; D025461:Feedback, Physiological / Q000502:physiology; D005260:Female; D005684:Gait / Q000502:physiology; D020233:Gait Disorders, Neurologic / Q000209:etiology / Q000503:physiopathology / Q000534:rehabilitation; D006801:Humans; D007717:Knee / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology*; D009989:Orthotic Devices; D010291:Paresis / Q000209:etiology / Q000503:physiopathology* / Q000534:rehabilitation*; D052097:Quadriceps Muscle / Q000503:physiopathology; D012026:Reflex, Stretch / Q000502:physiology; D020521:Stroke / Q000150:complications / Q000503:physiopathology*; D000071939:Stroke Rehabilitation; D016474:Weight-Bearing / Q000502:physiology*
keywords: Force feedback; Gait; Rehabilitation; Stiff-knee gait; Stroke