Pedrosa Gustavo Ferreira, Machado Sandra Carvalho, Diniz Rodrigo César Ribeiro, de Lacerda Lucas Túlio, Martins-Costa Hugo Cesar, de Andrade André Gustavo Pereira, Bemben Michael, Chagas Mauro Heleno, Lima Fernando Vitor
Weight Training Laboratory, School of Physical Education, Physiotherapy and Occupational Therapy of the Federal University of Minas Gerais, Belo Horizonte, Brazil.
Centro de Instrução e Adaptação da Aeronáutica, Lagoa Santa, Brazil.
J Hum Kinet. 2020 Jul 21;73:33-44. doi: 10.2478/hukin-2019-0132. eCollection 2020 Jul.
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.
本研究比较了在肌肉疲劳前采用不同向心/离心持续时间方案时的肌电图反应、血乳酸浓度（BLC）和最大重复次数（MNR）。这种比较可能有助于理解不同的向心/离心持续时间如何影响训练有素男性的运动表现以及中枢和代谢反应。17名力量训练男性采用平衡设计进行了两种方案。使用每种方案（4秒向心/2秒离心[4 s: 2 s]；以及2秒向心/4秒离心[2 s: 4 s]），以一次重复最大值（1RM）的60%进行三组史密斯卧推练习直至疲劳。比较了胸大肌和肱三头肌在第一次、中间和最后一次重复时肌电信号的归一化均方根（EMGRMS）和平均频率（EMGMF）。在测试前、测试期间和测试后评估BLC。为了比较肌电图和BLC，使用了带有事后Tukey检验的重复测量三因素方差分析。为了比较各组间的MNR，使用了带有Dunn事后检验的方差分析类型秩检验。方差分析表明，在中间和最后一次重复时，4 s: 2 s方案的胸大肌EMGRMS更高，而4 s: 2 s方案的肱三头肌EMGMF更低。两种方案在重复过程中均增加了EMGRMS并降低了EMGMF。尽管结果显示不同方案之间的激活水平和神经肌肉疲劳程度不同，但BLC和MNR相似。
