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Titolo:
FATIGUE IN HUMAN THENAR MUSCLES PARALYZED BY SPINAL-CORD INJURY
Autore:
THOMAS CK;
Indirizzi:
MIAMI PROJECT CURE PARALYSIS,1600 NW 10TH AVE,R-48 MIAMI FL 33136 UNIV MIAMI,SCH MED,DEPT NEUROL SURG MIAMI FL 00000
Titolo Testata:
Journal of electromyography and kinesiology
fascicolo: 1, volume: 7, anno: 1997,
pagine: 15 - 26
SICI:
1050-6411(1997)7:1<15:FIHTMP>2.0.ZU;2-2
Fonte:
ISI
Lingua:
ENG
Soggetto:
MAXIMAL VOLUNTARY CONTRACTIONS; MOTONEURON FIRING RATES; RATE CHRONIC STIMULATION; MOTOR-AXON STIMULATION; FAST-TWITCH MUSCLE; ELECTRICAL-STIMULATION; PHYSIOLOGICAL AMOUNTS; EXCITATION-FREQUENCY; CAT HINDLIMB; UNITS;
Keywords:
FORCE LOSS; CONTRACTILE FAILURE; M-WAVE; VARIABLE RATE STIMULATION; CONSTANT RATE STIMULATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
35
Recensione:
Indirizzi per estratti:
Citazione:
C.K. Thomas, "FATIGUE IN HUMAN THENAR MUSCLES PARALYZED BY SPINAL-CORD INJURY", Journal of electromyography and kinesiology, 7(1), 1997, pp. 15-26

Abstract

Muscle fatigue (force loss) induced by constant frequency stimulation(36 Hz) and variable rate stimulation (36 Hz to 18 Hz over 60 s) werecompared in six individuals with thenar muscles which were paralysed by chronic cervical spinal cord injury (SCI), and in six volunteers with no known neurological disorder. The variable stimulation rate pattern represented the general decline in thenar motor unit firing rates recorded during 60 s maximum voluntary contractions performed by the able-bodied (AB) subjects. Constant and variable rate stimulation produced similar resultant force declines, as measured from abduction and flexion force components. However, significant force loss always occurred earlier and was of greater magnitude in SCI subjects, irrespective of the stimulation pattern (all, P<0.01). Because more force was generally lost in one force component versus the other, the direction of theresultant force could also change with fatigue. The recordings from SCI participants were also contaminated by spontaneous motor unit activity, spasms and F responses. The stimulation frequency needed to produce half-maximum tetanic force increased for SCI subjects after fatigue, so higher, not lower stimulation frequencies were needed to produce any given submaximal force. Therefore, to match stimulation rate to changes in muscle contractile properties, these parameters have to be monitored and controlled on-line. The fatigue during each stimulation protocol, and for each subject population, was attributed primarily to contractile failure because any decrements in M-wave amplitude or area recovered completely within the first minute whereas twitch and tetanic forces remained somewhat depressed. (C) 1997 Elsevier Science Ltd.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 15/07/20 alle ore 13:40:57