Cui Xinwen, Zhang Yimin, Wang Zan, Yu Jingjing, Kong Zhenxing, Ružić Lana
China Institute of Sport Science, Dongcheng District, Beijing, China.
Beijing Sport University, Haidian District, Beijing, China.
Exp Physiol. 2019 Oct;104(10):1505-1517. doi: 10.1113/EP087601. Epub 2019 Aug 29.
What is the central question of this study? What are the adaptations of protein synthesis and degradation that occur in skeletal muscle in response to high-intensity interval training (HIIT), and what are the magnitudes of the changes in response to HIIT, compared to moderate-intensity continuous training (MICT), and the mechanisms underlying these changes? What is the main finding and its importance? HIIT is more effective than MICT in altering the expression of muscle RING-finger protein-1 and muscle atrophy F-box, and enhancing the autophagic flux in rat soleus muscle. In addition, HIIT could activate the mechanistic target of rapamycin pathway. These findings suggest that HIIT might be an effective exercise strategy for health promotion in skeletal muscle.
This study aimed to investigate the impact of high-intensity interval training (HIIT) on the proteins involved in protein synthesis, the ubiquitin-proteasome system (UPS) and autophagy in skeletal muscle of middle-aged rats. Nine-month-old male Wistar rats (n = 56) were randomly divided into three groups: a control (C) group, a moderate-intensity continuous training (MICT) group and a HIIT group. Rats in the training groups ran on treadmills 5 days per week for 8 weeks. The MICT group ran for 50 min at 60% , while the HIIT group ran for 3 min at 80% of six times separated by 3-min periods at 40% . Aerobic endurance, number of autophagosomes and expression of proteins involved in protein synthesis and degradation in the soleus muscle were measured at three time points: before training, after 4 weeks and after 8 weeks of training. Compared to the C group, HIIT and MICT increased the expression of phosphorylated mechanistic target of rapamycin (mTOR) after 8 weeks (P < 0.05 and P < 0.01, respectively). HIIT increased the expression of muscle RING-finger protein-1 (MuRF-1) after 4 weeks (P < 0.01), and decreased its expression after 8 weeks (P < 0.01). Both HIIT and MICT decreased the expression of muscle atrophy F-box (MAFbx) after 4 weeks (P < 0.05). HIIT improved the expression of microtubule-associated protein 1A/1B-light chain 3 (LC3)-II (P < 0.05), and decreased the P62 content (P < 0.01) after 4 weeks. The LC3II/LC3I ratio was increased after 8 weeks (P < 0.01). This study demonstrated that HIIT could activate the mTOR pathway, alter the expression of MuRF-1 and MAFbx proteins, and enhance autophagic flux in soleus muscle of middle-aged rats.
本研究的核心问题是什么？骨骼肌对高强度间歇训练（HIIT）产生的蛋白质合成与降解的适应性变化是什么？与中等强度持续训练（MICT）相比，HIIT引起的变化幅度如何？这些变化的潜在机制是什么？主要发现及其重要性是什么？HIIT在改变大鼠比目鱼肌中肌肉环状指蛋白-1和肌肉萎缩F盒蛋白的表达以及增强自噬通量方面比MICT更有效。此外，HIIT可激活雷帕霉素作用靶点通路。这些发现表明，HIIT可能是促进骨骼肌健康的有效运动策略。
本研究旨在探讨高强度间歇训练（HIIT）对中年大鼠骨骼肌中参与蛋白质合成、泛素-蛋白酶体系统（UPS）和自噬的蛋白质的影响。将9月龄雄性Wistar大鼠（n = 56）随机分为三组：对照组（C组）、中等强度持续训练（MICT）组和HIIT组。训练组大鼠每周在跑步机上跑5天，持续8周。MICT组以60%的最大摄氧量跑50分钟，而HIIT组以80%的最大摄氧量跑3分钟，共6次，每次间隔3分钟的40%最大摄氧量恢复期。在训练前、训练4周后和训练8周后三个时间点测量比目鱼肌的有氧耐力、自噬体数量以及参与蛋白质合成和降解的蛋白质表达。与C组相比，HIIT组和MICT组在8周后磷酸化雷帕霉素作用靶点（mTOR）的表达增加（分别为P < 0.05和P < 0.01）。HIIT组在4周后肌肉环状指蛋白-1（MuRF-1）的表达增加（P < 0.01），8周后表达下降（P < 0.01）。HIIT组和MICT组在4周后肌肉萎缩F盒蛋白（MAFbx）的表达均下降（P < 0.05）。HIIT组在4周后微管相关蛋白1A/1B轻链3（LC3）-II的表达增加（P < 0.05），P62含量下降（P < 0.01）。8周后LC3II/LC3I比值增加（P < 0.01）。本研究表明，HIIT可激活mTOR通路，改变MuRF-1和MAFbx蛋白的表达，并增强中年大鼠比目鱼肌的自噬通量。
