Low-frequency fatigue at maximal and submaximal muscle contractions
Braz. j. med. biol. res
;
42(4): 380-385, Apr. 2009. graf
Artigo
em Inglês
| LILACS
| ID: lil-509170
ABSTRACT
Skeletal muscle force production following repetitive contractions is preferentially reduced when muscle is evaluated with low-frequency stimulation. This selective impairment in force generation is called low-frequency fatigue (LFF) and could be dependent on the contraction type. The purpose of this study was to compare LFF after concentric and eccentric maximal and submaximal contractions of knee extensor muscles. Ten healthy male subjects (age 23.6 ± 4.2 years; weight 73.8 ± 7.7 kg; height 1.79 ± 0.05 m) executed maximal voluntary contractions that were measured before a fatigue test (pre-exercise), immediately after (after-exercise) and after 1 h of recovery (after-recovery). The fatigue test consisted of 60 maximal (100 percent) or submaximal (40 percent) dynamic concentric or eccentric knee extensions at an angular velocity of 60°/s. The isometric torque produced by low- (20 Hz) and high- (100 Hz) frequency stimulation was also measured at these times and the 20100 Hz ratio was calculated to assess LFF. One-way ANOVA for repeated measures followed by the Newman-Keuls post hoc test was used to determine significant (P < 0.05) differences. LFF was evident after-recovery in all trials except following submaximal eccentric contractions. LFF was not evident after-exercise, regardless of exercise intensity or contraction type. Our results suggest that low-frequency fatigue was evident after submaximal concentric but not submaximal eccentric contractions and was more pronounced after 1-h of recovery.
Texto completo:
DisponíveL
Índice:
LILACS (Américas)
Assunto principal:
Músculo Esquelético
/
Fadiga Muscular
/
Contração Muscular
Limite:
Adulto
/
Humanos
/
Masculino
Idioma:
Inglês
Revista:
Braz. j. med. biol. res
Assunto da revista:
Biologia
/
Medicina
Ano de publicação:
2009
Tipo de documento:
Artigo
País de afiliação:
Brasil
/
Canadá
Instituição/País de afiliação:
Universidade Federal do Rio Grande do Sul/BR
/
Universidade Tecnológica Federal do Paraná/BR
/
University of Calgary/CA
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