Muscle sympathetic nerve activity during intermittent handgrip exercise.
J Sports Med Phys Fitness
; 52(6): 665-73, 2012 Dec.
Article
em En
| MEDLINE
| ID: mdl-23187331
ABSTRACT
AIM:
This study evaluated whether central command plays an important role in activating muscle sympathetic nerve activity (MSNA) during short-term maximal handgrip contractions.METHODS:
The increase in MSNA was examined while influence of minimizing for other factors such as mechanoreflex, metaboreflex and fatigue during repetitive exercise in seven 19- to 26-year-old participants. Maximal voluntary handgrips (15-s contraction with a 45-s relaxation) were performed 10 times with a 15-s pause between alternate hands. MSNA was recorded from the tibial nerve analyzed using the burst frequency (BF) and total sympathetic nerve activity.RESULTS:
The BF increased with the first unit, from 14.9±1.8 bursts·min-1 at baseline to 27.7±3.4 bursts·min-1 during contraction. The increase in the MSNA during contractions remained unchanged throughout the repetitions. The BF declined to baseline during the relaxation periods. The peak grip force decreased from 333±25 N for the first grip to 216±20 N for the last contraction. The MSAN increase remained constant despite a possible reduction in mechanoreflex during exercise as indicated from decreased maximal handgrip force.CONCLUSION:
We suggested that the MSNA response was induced mainly by central command during short-term maximal handgrip contraction without metaboreflex influence and attenuated mechanoreflex input.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Sistema Nervoso Simpático
/
Exercício Físico
/
Músculo Esquelético
/
Força da Mão
/
Contração Isométrica
Limite:
Adult
/
Female
/
Humans
/
Male
Idioma:
En
Revista:
J Sports Med Phys Fitness
Ano de publicação:
2012
Tipo de documento:
Article
País de afiliação:
Japão