Dynamic Fatigue Does Not Alter Soleus H-Reflexes Conditioned by Homonymous or Heteronymous Pathways

Preeti D Oza; Shauna Dudley-Javoroski; Richard K Shields

doi:10.1123/mc.2016-0030

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Dynamic Fatigue Does Not Alter Soleus H-Reflexes Conditioned by Homonymous or Heteronymous Pathways

Journal article

Peer reviewed

Dynamic Fatigue Does Not Alter Soleus H-Reflexes Conditioned by Homonymous or Heteronymous Pathways

Preeti D Oza, Shauna Dudley-Javoroski and Richard K Shields

Motor control, Vol.21(3), pp.345-358

07/2017

DOI: 10.1123/mc.2016-0030

PMCID: PMC5604332

PMID: 27736308

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https://www.ncbi.nlm.nih.gov/pmc/articles/5604332View

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Abstract

H-reflex depression (diminution of amplitude after a conditioning stimulus) is mediated presynaptically and therefore can help distinguish central versus peripheral mechanisms of fatigue. We examined the effects of a dynamic exercise protocol on H-reflex depression using two conditioning methods: homonymous conditioning (paired-pulse tibial nerve stimulation); and heteronymous conditioning (common peroneal nerve stimulation). Ten subjects performed dynamic contractions of the soleus muscle through 30° ankle range of motion. The concentric phase required a target force of 10% of maximum voluntary isometric contraction (MVIC) and the eccentric phase force target was 80% MVIC. Fatigue persisted for >20 min after cessation of the exercise. Compared with prefatigue values, the dynamic fatigue protocol did not increase presynaptic inhibition after either homonymous or heteronymous conditioning. Peak to peak amplitude of unconditioned H-reflexes was likewise unchanged despite a long term depression of muscle force (long duration fatigue). These results suggest that persistent fatigue after dynamic exercise is attributed to muscle changes and not altered spinal mechanisms.

H-Reflex - physiology

Humans

Fatigue - physiopathology

Adult

Female

Male

Muscle, Skeletal - physiology

Electromyography - methods

Details

Title: Subtitle: Dynamic Fatigue Does Not Alter Soleus H-Reflexes Conditioned by Homonymous or Heteronymous Pathways
Creators: Preeti D Oza - 1 University of the Pacific
Shauna Dudley-Javoroski - 2 University of Iowa
Richard K Shields - 2 University of Iowa
Resource Type: Journal article
Publication Details: Motor control, Vol.21(3), pp.345-358
DOI: 10.1123/mc.2016-0030
PMID: 27736308
PMCID: PMC5604332
NLM abbreviation: Motor Control
ISSN: 1087-1640
eISSN: 1543-2696
Publisher: United States
Grant note: R01 HD084645 / NICHD NIH HHS R01 HD082109 / NICHD NIH HHS
Language: English
Date published: 07/2017
Academic Unit: Orthopedics and Rehabilitation; Physical Therapy and Rehabilitation Science
Record Identifier: 9984047852402771

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