Document Detail

The effects of unilateral muscle fatigue on bilateral physiological tremor.
MedLine Citation:
PMID:  16078030     Owner:  NLM     Status:  MEDLINE    
The aim of this study was to examine the post-exercise effects of fatiguing the wrist extensor muscles of a single arm on postural tremor and muscle activity in both arms. Previous research has shown that, for neurologically normal subjects, the tremor seen within a single limb segment is uncorrelated to that seen contralaterally. However it has been speculated that some bilateral relation does exist, and that the nature of the relation may only become evident under conditions where the neuromuscular system is perturbed. To further investigate this potential bilateral relation, seven healthy subjects were required to adopt a bilateral postural pointing position after exercise-induced fatigue of the wrist extensor muscles of a single arm. Tremor from the forearm, hand and finger segments of each arm, surface EMG activity from extensor digitorum (ED) of each arm, and blood lactate data were collected prior to and after the exercise intervention. The main result was that fatiguing the distal muscles of one arm resulted in a bilateral increase in both the physiological tremor and ED activity. The change in tremor was confined to the index finger with no change in the tremor for the hand or forearm segments of either arm. While three peaks were seen in the frequency profile of the finger tremor, the effects of fatigue were confined to an increase in the peak power of the neurally generated 8-12 Hz tremor component. The contralateral increase in muscle activity was also reflected by a change in the frequency profile of the EMG output, with an increase in the peak power of both muscles following exercise of the wrist extensors of a single arm. The bilateral increases in physiological tremor and EMG activity of ED were only observed during the bilateral pointing task, with no changes in tremor or EMG activity seen for the non-exercised limb during the unilateral exercise protocol. The specificity of the resultant increases in the neurally generated 8-12 Hz component of finger tremor amplitude and EMG activity, coupled with the lack of any changes in tremor for the more proximal arm segments, indicate that these bilateral effects were mediated by an increase in the central neural drive to both limbs. Together this set of results challenges the general assumption of bilateral independence of tremor production, and further illustrate the task dependent nature of exercise-induced fatigue.
S Morrison; J Kavanagh; S J Obst; J Irwin; L J Haseler
Publication Detail:
Type:  Clinical Trial; Journal Article     Date:  2005-08-03
Journal Detail:
Title:  Experimental brain research     Volume:  167     ISSN:  0014-4819     ISO Abbreviation:  Exp Brain Res     Publication Date:  2005 Dec 
Date Detail:
Created Date:  2005-11-28     Completed Date:  2006-03-29     Revised Date:  2013-12-13    
Medline Journal Info:
Nlm Unique ID:  0043312     Medline TA:  Exp Brain Res     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  609-21     Citation Subset:  IM    
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MeSH Terms
Data Interpretation, Statistical
Functional Laterality / physiology
Lactic Acid / metabolism
Muscle Contraction / physiology
Muscle Fatigue / physiology*
Muscle, Skeletal / metabolism,  physiology
Posture / physiology
Tremor / metabolism,  physiopathology*
Wrist / physiology
Reg. No./Substance:
33X04XA5AT/Lactic Acid

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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