Department of Kinesiology, McMaster University, Ontario, CANADA.
Human Physiology, Korea National Sport University, Seoul, SOUTH KOREA.
Med Sci Sports Exerc. 2019 Dec;51(12):2578-2585. doi: 10.1249/MSS.0000000000002088.
Lower-load (LL), higher-repetition resistance exercise training (RET) can increase muscle mass in a similar degree as higher-load (HL), lower-repetition RET. However, little is known about how LL and HL RET modulate other aspects of the RET phenotype such as satellite cells, myonuclei, and mitochondrial proteins. We aimed to investigate changes in muscle mass, muscle strength, satellite cell activity, myonuclear addition, and mitochondrial protein content after prolonged RET with LL and HL RET.
We recruited 21 young men and randomly assigned them to perform 10 wk RET (leg press, leg extension, and leg curl) three times per week with the following conditions: 80FAIL (80% one-repetition maximum [1RM] performed to volitional fatigue), 30WM (30%1RM with volume matched to 80FAIL), and 30FAIL (30%1RM to volitional fatigue). Skeletal muscle biopsies were taken from the vastus lateralis pre- and post-RET intervention.
After 10 wk of RET, only 30FAIL and 80FAIL showed an increase in peak torque and type I fiber cross-sectional area (P < 0.05). Moreover, only 30FAIL resulted in a significant decrease in the myonuclear domain of type II muscle fibers and an increase in mitochondrial proteins related to autophagy, fission, and fusion (all P < 0.05).
We discovered that LL RET was effective at increasing the content of several mitochondrial proteins. Similar to previous research, we found that changes in muscle mass and strength were independent of load when repetitions were performed to volitional fatigue.
低负荷（LL）、高重复次数的抗阻训练（RET）可以在类似程度上增加肌肉量，与高负荷（HL）、低重复次数的 RET 相似。然而，对于低负荷和高负荷 RET 如何调节 RET 表型的其他方面，如卫星细胞、肌核和线粒体蛋白，知之甚少。我们旨在研究经过长时间的低负荷和高负荷 RET 后，肌肉质量、肌肉力量、卫星细胞活性、肌核添加和线粒体蛋白含量的变化。
我们招募了 21 名年轻男性，并将他们随机分配到每周进行 3 次抗阻训练（腿推、腿伸展和腿弯举），以下列条件进行：80FAIL（80% 1 次重复最大重量[1RM]做到力竭）、30WM（30%1RM，容量与 80FAIL 匹配）和 30FAIL（30%1RM 做到力竭）。在抗阻训练干预前后，从股外侧肌采集骨骼肌活检。
经过 10 周的抗阻训练，只有 30FAIL 和 80FAIL 显示出峰值扭矩和 I 型纤维横截面积的增加（P<0.05）。此外，只有 30FAIL 导致 II 型肌纤维的肌核区域显著减小，并增加了与自噬、分裂和融合相关的线粒体蛋白（均 P<0.05）。
我们发现低负荷抗阻训练有效地增加了几种线粒体蛋白的含量。与之前的研究相似，我们发现当重复次数做到力竭时，肌肉质量和力量的变化与负荷无关。
