Experimental Brain Research

, Volume 237, Issue 1, pp 121–135 | Cite as

Biomechanical parameters of the elbow stretch reflex in chronic hemiparetic stroke

  • Jacob G. McPherson
  • Arno H. A. Stienen
  • Brian D. Schmit
  • Julius P. A. DewaldEmail author
Research Article


We sought to determine the relative velocity sensitivity of stretch reflex threshold angle and reflex stiffness during stretches of the paretic elbow joint in individuals with chronic hemiparetic stroke, and to provide guidelines to streamline spasticity assessments. We applied ramp-and-hold elbow extension perturbations ranging from 15 to 150°/s over the full range of motion in 13 individuals with hemiparesis. After accounting for the effects of passive mechanical resistance, we modeled velocity-dependent reflex threshold angle and torque–angle slope to determine their correlation with overall resistance to movement. Reflex stiffness exhibited substantially greater velocity sensitivity than threshold angle, accounting for ~ 74% (vs. ~ 15%) of the overall velocity-dependent increases in movement resistance. Reflex stiffness is a sensitive descriptor of the overall velocity-dependence of movement resistance in spasticity. Clinical spasticity assessments can be streamlined using torque–angle slope, a measure of reflex stiffness, as their primary outcome measure, particularly at stretch velocities greater than 100°/s.


Spasticity Stretch reflex Movement resistance Joint torque Threshold angle Stroke 



National Institutes of Health (NIH) Grant: 5R01HD039343.


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  • Jacob G. McPherson
    • 1
  • Arno H. A. Stienen
    • 2
  • Brian D. Schmit
    • 3
  • Julius P. A. Dewald
    • 2
    Email author
  1. 1.Department of Biomedical EngineeringFlorida International UniversityMiamiUSA
  2. 2.Department of Physical Therapy and Human Movement Sciences, Feinberg School of MedicineNorthwestern UniversityChicagoUSA
  3. 3.Department of Biomedical EngineeringMarquette UniversityMilwaukeeUSA

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