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dc.contributor.authorKao, Pei-Chunen_US
dc.contributor.authorLewis, Cara L.en_US
dc.contributor.authorFerris, Daniel P.en_US
dc.date.accessioned2012-01-12T16:42:29Z
dc.date.available2012-01-12T16:42:29Z
dc.date.copyright2010
dc.date.issued2010-7-26
dc.identifier.citationKao, Pei-Chun, Cara L Lewis, Daniel P Ferris. "Short-term locomotor adaptation to a robotic ankle exoskeleton does not alter soleus Hoffmann reflex amplitude" Journal of Neuroengineering and Rehabilitation 7:33. (2010)
dc.identifier.issn1743-0003
dc.identifier.urihttps://hdl.handle.net/2144/3363
dc.description.abstractBACKGROUND To improve design of robotic lower limb exoskeletons for gait rehabilitation, it is critical to identify neural mechanisms that govern locomotor adaptation to robotic assistance. Previously, we demonstrated soleus muscle recruitment decreased by ~35% when walking with a pneumatically-powered ankle exoskeleton providing plantar flexor torque under soleus proportional myoelectric control. Since a substantial portion of soleus activation during walking results from the stretch reflex, increased reflex inhibition is one potential mechanism for reducing soleus recruitment when walking with exoskeleton assistance. This is clinically relevant because many neurologically impaired populations have hyperactive stretch reflexes and training to reduce the reflexes could lead to substantial improvements in their motor ability. The purpose of this study was to quantify soleus Hoffmann (H-) reflex responses during powered versus unpowered walking. METHODS We tested soleus H-reflex responses in neurologically intact subjects (n=8) that had trained walking with the soleus controlled robotic ankle exoskeleton. Soleus H-reflex was tested at the mid and late stance while subjects walked with the exoskeleton on the treadmill at 1.25 m/s, first without power (first unpowered), then with power (powered), and finally without power again (second unpowered). We also collected joint kinematics and electromyography. RESULTS When the robotic plantar flexor torque was provided, subjects walked with lower soleus electromyographic (EMG) activation (27-48%) and had concomitant reductions in H-reflex amplitude (12-24%) compared to the first unpowered condition. The H-reflex amplitude in proportion to the background soleus EMG during powered walking was not significantly different from the two unpowered conditions. CONCLUSION These findings suggest that the nervous system does not inhibit the soleus H-reflex in response to short-term adaption to exoskeleton assistance. Future studies should determine if the findings also apply to long-term adaption to the exoskeleton.en_US
dc.description.sponsorshipNational Istitute of Health (R21 NS062119, F32 HD055010)en_US
dc.language.isoenen_US
dc.publisherBioMed Centralen_US
dc.rightsCopyright 2010 Kao et al; licensee BioMed Central Ltd.en_US
dc.rights.urihttp://creativecommons.org/licenses/by/2.0
dc.titleShort-Term Locomotor Adaptation to a Robotic Ankle Exoskeleton Does not Alter Soleus Hoffmann Reflex Amplitudeen_US
dc.typeArticleen_US
dc.identifier.doi10.1186/1743-0003-7-33
dc.identifier.pmid20659331
dc.identifier.pmcid2917445


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Copyright 2010 Kao et al; licensee BioMed Central Ltd.
Except where otherwise noted, this item's license is described as Copyright 2010 Kao et al; licensee BioMed Central Ltd.