The effects of altering the concentric/eccentric phase times on EMG response, lactate accumulation and work completed when training to failure
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Universidade Federal de Minas Gerais
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Artigo de periódico
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This study compared the electromyographic response, the blood lactate concentration (BLC), and the maximum
number of repetitions (MNR) between protocols of different concentric/eccentric duration taken to muscle failure. This
comparison may help to understand how different concentric/eccentric duration may influence performance and the
central and metabolic responses in trained men. Seventeen strength-trained men performed two protocols in a
counterbalanced design. Three sets of the Smith bench press exercise were performed to failure at 60% of the one
repetition maximum (1RM) using each protocol (4-s concentric/2-s eccentric [4 s: 2 s]; and 2-s concentric/4-s eccentric
[2 s: 4 s]). The normalized root mean square (EMGRMS) and the mean frequency (EMGMF) of the electromyographic
signals for the pectoralis major and the triceps brachii were compared in the first, middle, and last repetitions. The BLC
was assessed at rest, during and after the test sessions. To compare the EMG and BLC, a 3-way ANOVA with repeated
measures with a post hoc Tukey’s test was used. To compare the MNR performed across the sets, an ANOVA-type rank
test with the Dunn’s post hoc test was used. The ANOVA indicated a greater EMGRMS for Protocol 4 s: 2 s in the
pectoralis major and a lower EMGMF for Protocol 4 s: 2 s in the triceps brachii at the middle and last repetitions. Both
protocols increased the EMGRMS and decreased the EMGMF across repetitions. Despite the results show different
levels of activation and neuromuscular fatigue between protocols, the BLC and the MNR were similar.
Abstract
Assunto
Fisiologia, Treinamento de Força, Fadiga
Palavras-chave
Physiology, Strength, Electromygraphy, Bench press, Central fatigue
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Endereço externo
https://sciendo.com/article/10.2478/hukin-2019-0132