NEUROMECHANICAL CONTRIBUTIONS TO LOWER EXTREMITY STIFFNESS DURING RUNNING AND HOPPING IN HEALTHY RUNNERS Public Deposited

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  • March 21, 2019
Creator
  • Goodwin, Jonathan
    • Affiliation: School of Medicine, Department of Allied Health Sciences, Curriculum in Human Movement Science
Abstract
  • Lower extremity stiffness (KLeg) describes how subjects attenuate load during ground contact while completing dynamic tasks. Alterations in KLeg are associated with increased risk for lower extremity injury. Previous data suggests that lesser mobility during a clinical exam is associated with greater KLeg in healthy runners. The purpose of our study was to analyze the neuromechanical contributions to KLeg during running and hopping in healthy runners. Additionally we analyzed the relationship between running and hopping while also examining the feasibility of utilizing a waist-mounted accelerometer to estimate KLeg in a clinical setting. We analyzed 70 healthy runners with a 2 session cross-sectional study. We collected musculotendinous stiffness of the ankle plantarflexors and knee extensors in session 1. In session 2, we collected KLeg during self-selected running as well as single leg hopping at 3 frequencies (1.5 Hz, self-selected, 3.0 Hz). We also collected waist-mounted accelerations as well as muscle activation of the ankle plantarflexors and knee extensors. We found that at self-selected frequencies and higher, greater KLeg during single leg hopping is significantly associated with greater ankle plantarflexor musculotendinous stiffness, greater ankle plantarflexor muscle activation and greater hopping frequency. Greater KLeg during running is significantly associated with greater knee extensor musculotendinous stiffness, lesser hip internal range of motion and greater running velocity. We found that subjects who demonstrated greater KLeg during single leg hopping also demonstrated greater KLeg during running however this significant relationship was only minimal. Finally, our waist-mounted accelerometer significantly overestimated KLeg across all hopping frequencies. Out study found that active muscle contraction and greater musculotendinous stiffness of the ankle plantflexors and knee extensors are associated with greater KLeg during hopping and running, respectively. These may serve as rehabilitative targets to alter KLeg in the clinical setting. Additionally, assessing KLeg via hopping and with a waist-mounted accelerometer does not accurately reflect KLeg during running determine via motion capture. Additional studies should be completed to improve the clinical assessment of KLeg to reduce the occurrence of lower extremity injuries.
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  • In Copyright
Advisor
  • Blackburn, J. Troy
  • Schwartz, Todd
  • Padua, Darin
  • Franz, Jason
  • Ryan, Eric
Degree
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2018
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