Reduced motor unit discharge rates of maximal velocity dynamic contractions in response to a submaximal dynamic fatigue protocol.
J Appl Physiol (1985)
; 113(12): 1821-30, 2012 Dec 15.
Article
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| MEDLINE
| ID: mdl-23085960
ABSTRACT
Fatigability is highly task dependent wherein motor unit (MU) discharge rates and recruitment thresholds are affected differently depending on whether contractions are performed at maximal or submaximal intensities. Although much is described for isometric tasks, the behavior of MU properties during the production of maximal velocity dynamic contractions following submaximal fatiguing contractions is unknown. In seven young men, we evaluated changes in MU recruitment thresholds and MU discharge rates of the anconeus muscle during both submaximal and maximal dynamic elbow extensions following a submaximal dynamic fatiguing protocol of moderate intensity to velocity task failure. Velocity and power of the maximal dynamic contractions declined â¼45 and â¼55%, respectively, but these variables were unchanged for the submaximal target velocity contractions. Discharge rates of the 12 MUs at task failure were unchanged for submaximal dynamic contractions, but were decreased â¼20% for maximal dynamic and ballistic isometric contractions at task failure. MU recruitment thresholds of submaximal dynamic contractions decreased 52% at task failure, but were similar throughout the fatiguing protocol for maximal contractions. These findings support the concept of a common neural mechanism responsible for the relative declines in MU discharge rate associated with submaximal fatigability in both isometric and dynamic contractions.
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Resistencia Física
/
Potenciales de Acción
/
Músculo Esquelético
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Fatiga Muscular
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Esfuerzo Físico
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Neuronas Motoras
Límite:
Adult
/
Humans
/
Male
Idioma:
En
Revista:
J Appl Physiol (1985)
Asunto de la revista:
FISIOLOGIA
Año:
2012
Tipo del documento:
Article
País de afiliación:
Canadá